ImGuizmo.cpp

// The MIT License(MIT)
//
// Copyright(c) 2016 Cedric Guillemet
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files(the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and / or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions :
//
// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.

#include "imgui.h"
#ifndef IMGUI_DEFINE_MATH_OPERATORS
#define IMGUI_DEFINE_MATH_OPERATORS
#endif
#include "imgui_internal.h"
#include "ImGuizmo.h"
#if !defined(_WIN32) 
#define _malloca(x) alloca(x)
#else
#include <malloc.h>
#endif

// includes patches for multiview from
// https://github.com/CedricGuillemet/ImGuizmo/issues/15

namespace ImGuizmo
{
   static const float ZPI = 3.14159265358979323846f;
   static const float RAD2DEG = (180.f / ZPI);
   static const float DEG2RAD = (ZPI / 180.f);
	static float gGizmoSizeClipSpace = 0.1f;
   const float screenRotateSize = 0.06f;

   ///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
   // utility and math

   void FPU_MatrixF_x_MatrixF(const float* a, const float* b, float* r)
   {
      r[0] = a[0] * b[0] + a[1] * b[4] + a[2] * b[8] + a[3] * b[12];
      r[1] = a[0] * b[1] + a[1] * b[5] + a[2] * b[9] + a[3] * b[13];
      r[2] = a[0] * b[2] + a[1] * b[6] + a[2] * b[10] + a[3] * b[14];
      r[3] = a[0] * b[3] + a[1] * b[7] + a[2] * b[11] + a[3] * b[15];

      r[4] = a[4] * b[0] + a[5] * b[4] + a[6] * b[8] + a[7] * b[12];
      r[5] = a[4] * b[1] + a[5] * b[5] + a[6] * b[9] + a[7] * b[13];
      r[6] = a[4] * b[2] + a[5] * b[6] + a[6] * b[10] + a[7] * b[14];
      r[7] = a[4] * b[3] + a[5] * b[7] + a[6] * b[11] + a[7] * b[15];

      r[8] = a[8] * b[0] + a[9] * b[4] + a[10] * b[8] + a[11] * b[12];
      r[9] = a[8] * b[1] + a[9] * b[5] + a[10] * b[9] + a[11] * b[13];
      r[10] = a[8] * b[2] + a[9] * b[6] + a[10] * b[10] + a[11] * b[14];
      r[11] = a[8] * b[3] + a[9] * b[7] + a[10] * b[11] + a[11] * b[15];

      r[12] = a[12] * b[0] + a[13] * b[4] + a[14] * b[8] + a[15] * b[12];
      r[13] = a[12] * b[1] + a[13] * b[5] + a[14] * b[9] + a[15] * b[13];
      r[14] = a[12] * b[2] + a[13] * b[6] + a[14] * b[10] + a[15] * b[14];
      r[15] = a[12] * b[3] + a[13] * b[7] + a[14] * b[11] + a[15] * b[15];
   }

   void Frustum(float left, float right, float bottom, float top, float znear, float zfar, float* m16)
   {
      float temp, temp2, temp3, temp4;
      temp = 2.0f * znear;
      temp2 = right - left;
      temp3 = top - bottom;
      temp4 = zfar - znear;
      m16[0] = temp / temp2;
      m16[1] = 0.0;
      m16[2] = 0.0;
      m16[3] = 0.0;
      m16[4] = 0.0;
      m16[5] = temp / temp3;
      m16[6] = 0.0;
      m16[7] = 0.0;
      m16[8] = (right + left) / temp2;
      m16[9] = (top + bottom) / temp3;
      m16[10] = (-zfar - znear) / temp4;
      m16[11] = -1.0f;
      m16[12] = 0.0;
      m16[13] = 0.0;
      m16[14] = (-temp * zfar) / temp4;
      m16[15] = 0.0;
   }

   void Perspective(float fovyInDegrees, float aspectRatio, float znear, float zfar, float* m16)
   {
      float ymax, xmax;
      ymax = znear * tanf(fovyInDegrees * DEG2RAD);
      xmax = ymax * aspectRatio;
      Frustum(-xmax, xmax, -ymax, ymax, znear, zfar, m16);
   }

   void Cross(const float* a, const float* b, float* r)
   {
      r[0] = a[1] * b[2] - a[2] * b[1];
      r[1] = a[2] * b[0] - a[0] * b[2];
      r[2] = a[0] * b[1] - a[1] * b[0];
   }

   float Dot(const float* a, const float* b)
   {
      return a[0] * b[0] + a[1] * b[1] + a[2] * b[2];
   }

   void Normalize(const float* a, float* r)
   {
      float il = 1.f / (sqrtf(Dot(a, a)) + FLT_EPSILON);
      r[0] = a[0] * il;
      r[1] = a[1] * il;
      r[2] = a[2] * il;
   }

   void LookAt(const float* eye, const float* at, const float* up, float* m16)
   {
      float X[3], Y[3], Z[3], tmp[3];

      tmp[0] = eye[0] - at[0];
      tmp[1] = eye[1] - at[1];
      tmp[2] = eye[2] - at[2];
      Normalize(tmp, Z);
      Normalize(up, Y);
      Cross(Y, Z, tmp);
      Normalize(tmp, X);
      Cross(Z, X, tmp);
      Normalize(tmp, Y);

      m16[0] = X[0];
      m16[1] = Y[0];
      m16[2] = Z[0];
      m16[3] = 0.0f;
      m16[4] = X[1];
      m16[5] = Y[1];
      m16[6] = Z[1];
      m16[7] = 0.0f;
      m16[8] = X[2];
      m16[9] = Y[2];
      m16[10] = Z[2];
      m16[11] = 0.0f;
      m16[12] = -Dot(X, eye);
      m16[13] = -Dot(Y, eye);
      m16[14] = -Dot(Z, eye);
      m16[15] = 1.0f;
   }

   template <typename T> T Clamp(T x, T y, T z) { return ((x < y) ? y : ((x > z) ? z : x)); }
   template <typename T> T max(T x, T y) { return (x > y) ? x : y; }
   template <typename T> T min(T x, T y) { return (x < y) ? x : y; }
   template <typename T> bool IsWithin(T x, T y, T z) { return (x >= y) && (x <= z); }

   struct matrix_t;
   struct vec_t
   {
   public:
      float x, y, z, w;

      void Lerp(const vec_t& v, float t)
      {
         x += (v.x - x) * t;
         y += (v.y - y) * t;
         z += (v.z - z) * t;
         w += (v.w - w) * t;
      }

      void Set(float v) { x = y = z = w = v; }
      void Set(float _x, float _y, float _z = 0.f, float _w = 0.f) { x = _x; y = _y; z = _z; w = _w; }

      vec_t& operator -= (const vec_t& v) { x -= v.x; y -= v.y; z -= v.z; w -= v.w; return *this; }
      vec_t& operator += (const vec_t& v) { x += v.x; y += v.y; z += v.z; w += v.w; return *this; }
      vec_t& operator *= (const vec_t& v) { x *= v.x; y *= v.y; z *= v.z; w *= v.w; return *this; }
      vec_t& operator *= (float v) { x *= v;    y *= v;    z *= v;    w *= v;    return *this; }

      vec_t operator * (float f) const;
      vec_t operator - () const;
      vec_t operator - (const vec_t& v) const;
      vec_t operator + (const vec_t& v) const;
      vec_t operator * (const vec_t& v) const;

      const vec_t& operator + () const { return (*this); }
      float Length() const { return sqrtf(x * x + y * y + z * z); };
      float LengthSq() const { return (x * x + y * y + z * z); };
      vec_t Normalize() { (*this) *= (1.f / Length()); return (*this); }
      vec_t Normalize(const vec_t& v) { this->Set(v.x, v.y, v.z, v.w); this->Normalize(); return (*this); }
      vec_t Abs() const;

      void Cross(const vec_t& v)
      {
         vec_t res;
         res.x = y * v.z - z * v.y;
         res.y = z * v.x - x * v.z;
         res.z = x * v.y - y * v.x;

         x = res.x;
         y = res.y;
         z = res.z;
         w = 0.f;
      }

      void Cross(const vec_t& v1, const vec_t& v2)
      {
         x = v1.y * v2.z - v1.z * v2.y;
         y = v1.z * v2.x - v1.x * v2.z;
         z = v1.x * v2.y - v1.y * v2.x;
         w = 0.f;
      }

      float Dot(const vec_t& v) const
      {
         return (x * v.x) + (y * v.y) + (z * v.z) + (w * v.w);
      }

      float Dot3(const vec_t& v) const
      {
         return (x * v.x) + (y * v.y) + (z * v.z);
      }

      void Transform(const matrix_t& matrix);
      void Transform(const vec_t& s, const matrix_t& matrix);

      void TransformVector(const matrix_t& matrix);
      void TransformPoint(const matrix_t& matrix);
      void TransformVector(const vec_t& v, const matrix_t& matrix) { (*this) = v; this->TransformVector(matrix); }
      void TransformPoint(const vec_t& v, const matrix_t& matrix) { (*this) = v; this->TransformPoint(matrix); }

      float& operator [] (size_t index) { return ((float*)&x)[index]; }
      const float& operator [] (size_t index) const { return ((float*)&x)[index]; }
      bool operator!=(const vec_t& other) const { return memcmp(this, &other, sizeof(vec_t)); }
   };

   vec_t makeVect(float _x, float _y, float _z = 0.f, float _w = 0.f) { vec_t res; res.x = _x; res.y = _y; res.z = _z; res.w = _w; return res; }
   vec_t makeVect(ImVec2 v) { vec_t res; res.x = v.x; res.y = v.y; res.z = 0.f; res.w = 0.f; return res; }
   vec_t vec_t::operator * (float f) const { return makeVect(x * f, y * f, z * f, w * f); }
   vec_t vec_t::operator - () const { return makeVect(-x, -y, -z, -w); }
   vec_t vec_t::operator - (const vec_t& v) const { return makeVect(x - v.x, y - v.y, z - v.z, w - v.w); }
   vec_t vec_t::operator + (const vec_t& v) const { return makeVect(x + v.x, y + v.y, z + v.z, w + v.w); }
   vec_t vec_t::operator * (const vec_t& v) const { return makeVect(x * v.x, y * v.y, z * v.z, w * v.w); }
   vec_t vec_t::Abs() const { return makeVect(fabsf(x), fabsf(y), fabsf(z)); }

   vec_t Normalized(const vec_t& v) { vec_t res; res = v; res.Normalize(); return res; }
   vec_t Cross(const vec_t& v1, const vec_t& v2)
   {
      vec_t res;
      res.x = v1.y * v2.z - v1.z * v2.y;
      res.y = v1.z * v2.x - v1.x * v2.z;
      res.z = v1.x * v2.y - v1.y * v2.x;
      res.w = 0.f;
      return res;
   }

   float Dot(const vec_t& v1, const vec_t& v2)
   {
      return (v1.x * v2.x) + (v1.y * v2.y) + (v1.z * v2.z);
   }

   vec_t BuildPlan(const vec_t& p_point1, const vec_t& p_normal)
   {
      vec_t normal, res;
      normal.Normalize(p_normal);
      res.w = normal.Dot(p_point1);
      res.x = normal.x;
      res.y = normal.y;
      res.z = normal.z;
      return res;
   }

   struct matrix_t
   {
   public:

      union
      {
         float m[4][4];
         float m16[16];
         struct
         {
            vec_t right, up, dir, position;
         } v;
         vec_t component[4];
      };

      matrix_t(const matrix_t& other) { memcpy(&m16[0], &other.m16[0], sizeof(float) * 16); }
      matrix_t() {}

      operator float* () { return m16; }
      operator const float* () const { return m16; }
      void Translation(float _x, float _y, float _z) { this->Translation(makeVect(_x, _y, _z)); }

      void Translation(const vec_t& vt)
      {
         v.right.Set(1.f, 0.f, 0.f, 0.f);
         v.up.Set(0.f, 1.f, 0.f, 0.f);
         v.dir.Set(0.f, 0.f, 1.f, 0.f);
         v.position.Set(vt.x, vt.y, vt.z, 1.f);
      }

      void Scale(float _x, float _y, float _z)
      {
         v.right.Set(_x, 0.f, 0.f, 0.f);
         v.up.Set(0.f, _y, 0.f, 0.f);
         v.dir.Set(0.f, 0.f, _z, 0.f);
         v.position.Set(0.f, 0.f, 0.f, 1.f);
      }
      void Scale(const vec_t& s) { Scale(s.x, s.y, s.z); }

      matrix_t& operator *= (const matrix_t& mat)
      {
         matrix_t tmpMat;
         tmpMat = *this;
         tmpMat.Multiply(mat);
         *this = tmpMat;
         return *this;
      }
      matrix_t operator * (const matrix_t& mat) const
      {
         matrix_t matT;
         matT.Multiply(*this, mat);
         return matT;
      }

      void Multiply(const matrix_t& matrix)
      {
         matrix_t tmp;
         tmp = *this;

         FPU_MatrixF_x_MatrixF((float*)&tmp, (float*)&matrix, (float*)this);
      }

      void Multiply(const matrix_t& m1, const matrix_t& m2)
      {
         FPU_MatrixF_x_MatrixF((float*)&m1, (float*)&m2, (float*)this);
      }

      float GetDeterminant() const
      {
         return m[0][0] * m[1][1] * m[2][2] + m[0][1] * m[1][2] * m[2][0] + m[0][2] * m[1][0] * m[2][1] -
            m[0][2] * m[1][1] * m[2][0] - m[0][1] * m[1][0] * m[2][2] - m[0][0] * m[1][2] * m[2][1];
      }

      float Inverse(const matrix_t& srcMatrix, bool affine = false);
      void SetToIdentity()
      {
         v.right.Set(1.f, 0.f, 0.f, 0.f);
         v.up.Set(0.f, 1.f, 0.f, 0.f);
         v.dir.Set(0.f, 0.f, 1.f, 0.f);
         v.position.Set(0.f, 0.f, 0.f, 1.f);
      }
      void Transpose()
      {
         matrix_t tmpm;
         for (int l = 0; l < 4; l++)
         {
            for (int c = 0; c < 4; c++)
            {
               tmpm.m[l][c] = m[c][l];
            }
         }
         (*this) = tmpm;
      }

      void RotationAxis(const vec_t& axis, float angle);

      void OrthoNormalize()
      {
         v.right.Normalize();
         v.up.Normalize();
         v.dir.Normalize();
      }
   };

   void vec_t::Transform(const matrix_t& matrix)
   {
      vec_t out;

      out.x = x * matrix.m[0][0] + y * matrix.m[1][0] + z * matrix.m[2][0] + w * matrix.m[3][0];
      out.y = x * matrix.m[0][1] + y * matrix.m[1][1] + z * matrix.m[2][1] + w * matrix.m[3][1];
      out.z = x * matrix.m[0][2] + y * matrix.m[1][2] + z * matrix.m[2][2] + w * matrix.m[3][2];
      out.w = x * matrix.m[0][3] + y * matrix.m[1][3] + z * matrix.m[2][3] + w * matrix.m[3][3];

      x = out.x;
      y = out.y;
      z = out.z;
      w = out.w;
   }

   void vec_t::Transform(const vec_t& s, const matrix_t& matrix)
   {
      *this = s;
      Transform(matrix);
   }

   void vec_t::TransformPoint(const matrix_t& matrix)
   {
      vec_t out;

      out.x = x * matrix.m[0][0] + y * matrix.m[1][0] + z * matrix.m[2][0] + matrix.m[3][0];
      out.y = x * matrix.m[0][1] + y * matrix.m[1][1] + z * matrix.m[2][1] + matrix.m[3][1];
      out.z = x * matrix.m[0][2] + y * matrix.m[1][2] + z * matrix.m[2][2] + matrix.m[3][2];
      out.w = x * matrix.m[0][3] + y * matrix.m[1][3] + z * matrix.m[2][3] + matrix.m[3][3];

      x = out.x;
      y = out.y;
      z = out.z;
      w = out.w;
   }

   void vec_t::TransformVector(const matrix_t& matrix)
   {
      vec_t out;

      out.x = x * matrix.m[0][0] + y * matrix.m[1][0] + z * matrix.m[2][0];
      out.y = x * matrix.m[0][1] + y * matrix.m[1][1] + z * matrix.m[2][1];
      out.z = x * matrix.m[0][2] + y * matrix.m[1][2] + z * matrix.m[2][2];
      out.w = x * matrix.m[0][3] + y * matrix.m[1][3] + z * matrix.m[2][3];

      x = out.x;
      y = out.y;
      z = out.z;
      w = out.w;
   }

   float matrix_t::Inverse(const matrix_t& srcMatrix, bool affine)
   {
      float det = 0;

      if (affine)
      {
         det = GetDeterminant();
         float s = 1 / det;
         m[0][0] = (srcMatrix.m[1][1] * srcMatrix.m[2][2] - srcMatrix.m[1][2] * srcMatrix.m[2][1]) * s;
         m[0][1] = (srcMatrix.m[2][1] * srcMatrix.m[0][2] - srcMatrix.m[2][2] * srcMatrix.m[0][1]) * s;
         m[0][2] = (srcMatrix.m[0][1] * srcMatrix.m[1][2] - srcMatrix.m[0][2] * srcMatrix.m[1][1]) * s;
         m[1][0] = (srcMatrix.m[1][2] * srcMatrix.m[2][0] - srcMatrix.m[1][0] * srcMatrix.m[2][2]) * s;
         m[1][1] = (srcMatrix.m[2][2] * srcMatrix.m[0][0] - srcMatrix.m[2][0] * srcMatrix.m[0][2]) * s;
         m[1][2] = (srcMatrix.m[0][2] * srcMatrix.m[1][0] - srcMatrix.m[0][0] * srcMatrix.m[1][2]) * s;
         m[2][0] = (srcMatrix.m[1][0] * srcMatrix.m[2][1] - srcMatrix.m[1][1] * srcMatrix.m[2][0]) * s;
         m[2][1] = (srcMatrix.m[2][0] * srcMatrix.m[0][1] - srcMatrix.m[2][1] * srcMatrix.m[0][0]) * s;
         m[2][2] = (srcMatrix.m[0][0] * srcMatrix.m[1][1] - srcMatrix.m[0][1] * srcMatrix.m[1][0]) * s;
         m[3][0] = -(m[0][0] * srcMatrix.m[3][0] + m[1][0] * srcMatrix.m[3][1] + m[2][0] * srcMatrix.m[3][2]);
         m[3][1] = -(m[0][1] * srcMatrix.m[3][0] + m[1][1] * srcMatrix.m[3][1] + m[2][1] * srcMatrix.m[3][2]);
         m[3][2] = -(m[0][2] * srcMatrix.m[3][0] + m[1][2] * srcMatrix.m[3][1] + m[2][2] * srcMatrix.m[3][2]);
      }
      else
      {
         // transpose matrix
         float src[16];
         for (int i = 0; i < 4; ++i)
         {
            src[i] = srcMatrix.m16[i * 4];
            src[i + 4] = srcMatrix.m16[i * 4 + 1];
            src[i + 8] = srcMatrix.m16[i * 4 + 2];
            src[i + 12] = srcMatrix.m16[i * 4 + 3];
         }

         // calculate pairs for first 8 elements (cofactors)
         float tmp[12]; // temp array for pairs
         tmp[0] = src[10] * src[15];
         tmp[1] = src[11] * src[14];
         tmp[2] = src[9] * src[15];
         tmp[3] = src[11] * src[13];
         tmp[4] = src[9] * src[14];
         tmp[5] = src[10] * src[13];
         tmp[6] = src[8] * src[15];
         tmp[7] = src[11] * src[12];
         tmp[8] = src[8] * src[14];
         tmp[9] = src[10] * src[12];
         tmp[10] = src[8] * src[13];
         tmp[11] = src[9] * src[12];

         // calculate first 8 elements (cofactors)
         m16[0] = (tmp[0] * src[5] + tmp[3] * src[6] + tmp[4] * src[7]) - (tmp[1] * src[5] + tmp[2] * src[6] + tmp[5] * src[7]);
         m16[1] = (tmp[1] * src[4] + tmp[6] * src[6] + tmp[9] * src[7]) - (tmp[0] * src[4] + tmp[7] * src[6] + tmp[8] * src[7]);
         m16[2] = (tmp[2] * src[4] + tmp[7] * src[5] + tmp[10] * src[7]) - (tmp[3] * src[4] + tmp[6] * src[5] + tmp[11] * src[7]);
         m16[3] = (tmp[5] * src[4] + tmp[8] * src[5] + tmp[11] * src[6]) - (tmp[4] * src[4] + tmp[9] * src[5] + tmp[10] * src[6]);
         m16[4] = (tmp[1] * src[1] + tmp[2] * src[2] + tmp[5] * src[3]) - (tmp[0] * src[1] + tmp[3] * src[2] + tmp[4] * src[3]);
         m16[5] = (tmp[0] * src[0] + tmp[7] * src[2] + tmp[8] * src[3]) - (tmp[1] * src[0] + tmp[6] * src[2] + tmp[9] * src[3]);
         m16[6] = (tmp[3] * src[0] + tmp[6] * src[1] + tmp[11] * src[3]) - (tmp[2] * src[0] + tmp[7] * src[1] + tmp[10] * src[3]);
         m16[7] = (tmp[4] * src[0] + tmp[9] * src[1] + tmp[10] * src[2]) - (tmp[5] * src[0] + tmp[8] * src[1] + tmp[11] * src[2]);

         // calculate pairs for second 8 elements (cofactors)
         tmp[0] = src[2] * src[7];
         tmp[1] = src[3] * src[6];
         tmp[2] = src[1] * src[7];
         tmp[3] = src[3] * src[5];
         tmp[4] = src[1] * src[6];
         tmp[5] = src[2] * src[5];
         tmp[6] = src[0] * src[7];
         tmp[7] = src[3] * src[4];
         tmp[8] = src[0] * src[6];
         tmp[9] = src[2] * src[4];
         tmp[10] = src[0] * src[5];
         tmp[11] = src[1] * src[4];

         // calculate second 8 elements (cofactors)
         m16[8] = (tmp[0] * src[13] + tmp[3] * src[14] + tmp[4] * src[15]) - (tmp[1] * src[13] + tmp[2] * src[14] + tmp[5] * src[15]);
         m16[9] = (tmp[1] * src[12] + tmp[6] * src[14] + tmp[9] * src[15]) - (tmp[0] * src[12] + tmp[7] * src[14] + tmp[8] * src[15]);
         m16[10] = (tmp[2] * src[12] + tmp[7] * src[13] + tmp[10] * src[15]) - (tmp[3] * src[12] + tmp[6] * src[13] + tmp[11] * src[15]);
         m16[11] = (tmp[5] * src[12] + tmp[8] * src[13] + tmp[11] * src[14]) - (tmp[4] * src[12] + tmp[9] * src[13] + tmp[10] * src[14]);
         m16[12] = (tmp[2] * src[10] + tmp[5] * src[11] + tmp[1] * src[9]) - (tmp[4] * src[11] + tmp[0] * src[9] + tmp[3] * src[10]);
         m16[13] = (tmp[8] * src[11] + tmp[0] * src[8] + tmp[7] * src[10]) - (tmp[6] * src[10] + tmp[9] * src[11] + tmp[1] * src[8]);
         m16[14] = (tmp[6] * src[9] + tmp[11] * src[11] + tmp[3] * src[8]) - (tmp[10] * src[11] + tmp[2] * src[8] + tmp[7] * src[9]);
         m16[15] = (tmp[10] * src[10] + tmp[4] * src[8] + tmp[9] * src[9]) - (tmp[8] * src[9] + tmp[11] * src[10] + tmp[5] * src[8]);

         // calculate determinant
         det = src[0] * m16[0] + src[1] * m16[1] + src[2] * m16[2] + src[3] * m16[3];

         // calculate matrix inverse
         float invdet = 1 / det;
         for (int j = 0; j < 16; ++j)
         {
            m16[j] *= invdet;
         }
      }

      return det;
   }

   void matrix_t::RotationAxis(const vec_t& axis, float angle)
   {
      float length2 = axis.LengthSq();
      if (length2 < FLT_EPSILON)
      {
         SetToIdentity();
         return;
      }

      vec_t n = axis * (1.f / sqrtf(length2));
      float s = sinf(angle);
      float c = cosf(angle);
      float k = 1.f - c;

      float xx = n.x * n.x * k + c;
      float yy = n.y * n.y * k + c;
      float zz = n.z * n.z * k + c;
      float xy = n.x * n.y * k;
      float yz = n.y * n.z * k;
      float zx = n.z * n.x * k;
      float xs = n.x * s;
      float ys = n.y * s;
      float zs = n.z * s;

      m[0][0] = xx;
      m[0][1] = xy + zs;
      m[0][2] = zx - ys;
      m[0][3] = 0.f;
      m[1][0] = xy - zs;
      m[1][1] = yy;
      m[1][2] = yz + xs;
      m[1][3] = 0.f;
      m[2][0] = zx + ys;
      m[2][1] = yz - xs;
      m[2][2] = zz;
      m[2][3] = 0.f;
      m[3][0] = 0.f;
      m[3][1] = 0.f;
      m[3][2] = 0.f;
      m[3][3] = 1.f;
   }

   ///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
   //

   enum MOVETYPE
   {
      NONE,
      MOVE_X,
      MOVE_Y,
      MOVE_Z,
      MOVE_YZ,
      MOVE_ZX,
      MOVE_XY,
      MOVE_SCREEN,
      ROTATE_X,
      ROTATE_Y,
      ROTATE_Z,
      ROTATE_SCREEN,
      SCALE_X,
      SCALE_Y,
      SCALE_Z,
      SCALE_XYZ
   };

   struct Context
   {
      Context() : mbUsing(false), mbEnable(true), mbUsingBounds(false)
      {
      }

      ImDrawList* mDrawList;

      MODE mMode;
      matrix_t mViewMat;
      matrix_t mProjectionMat;
      matrix_t mModel;
      matrix_t mModelInverse;
      matrix_t mModelSource;
      matrix_t mModelSourceInverse;
      matrix_t mMVP;
      matrix_t mViewProjection;

      vec_t mModelScaleOrigin;
      vec_t mCameraEye;
      vec_t mCameraRight;
      vec_t mCameraDir;
      vec_t mCameraUp;
      vec_t mRayOrigin;
      vec_t mRayVector;

      float  mRadiusSquareCenter;
      ImVec2 mScreenSquareCenter;
      ImVec2 mScreenSquareMin;
      ImVec2 mScreenSquareMax;

      float mScreenFactor;
      vec_t mRelativeOrigin;

      bool mbUsing;
      bool mbEnable;

      // translation
      vec_t mTranslationPlan;
      vec_t mTranslationPlanOrigin;
      vec_t mMatrixOrigin;
      vec_t mTranslationLastDelta;

      // rotation
      vec_t mRotationVectorSource;
      float mRotationAngle;
      float mRotationAngleOrigin;
      //vec_t mWorldToLocalAxis;

      // scale
      vec_t mScale;
      vec_t mScaleValueOrigin;
      vec_t mScaleLast;
      float mSaveMousePosx;

      // save axis factor when using gizmo
      bool mBelowAxisLimit[3];
      bool mBelowPlaneLimit[3];
      float mAxisFactor[3];

      // bounds stretching
      vec_t mBoundsPivot;
      vec_t mBoundsAnchor;
      vec_t mBoundsPlan;
      vec_t mBoundsLocalPivot;
      int mBoundsBestAxis;
      int mBoundsAxis[2];
      bool mbUsingBounds;
      matrix_t mBoundsMatrix;

      //
      int mCurrentOperation;

      float mX = 0.f;
      float mY = 0.f;
      float mWidth = 0.f;
      float mHeight = 0.f;
      float mXMax = 0.f;
      float mYMax = 0.f;
      float mDisplayRatio = 1.f;

      bool mIsOrthographic = false;

      int mActualID = -1;
      int mEditingID = -1;
      OPERATION mOperation = OPERATION(-1);
   };

   static Context gContext;

   static const float angleLimit = 0.96f;
   static const float planeLimit = 0.2f;

   static const vec_t directionUnary[3] = { makeVect(1.f, 0.f, 0.f), makeVect(0.f, 1.f, 0.f), makeVect(0.f, 0.f, 1.f) };
   static const ImU32 directionColor[3] = { 0xFF0000AA, 0xFF00AA00, 0xFFAA0000 };

   // Alpha: 100%: FF, 87%: DE, 70%: B3, 54%: 8A, 50%: 80, 38%: 61, 12%: 1F
   static const ImU32 planeColor[3] = { 0x610000AA, 0x6100AA00, 0x61AA0000 };
   static const ImU32 selectionColor = 0x8A1080FF;
   static const ImU32 inactiveColor = 0x99999999;
   static const ImU32 translationLineColor = 0xAAAAAAAA;
   static const char* translationInfoMask[] = { "X : %5.3f", "Y : %5.3f", "Z : %5.3f",
      "Y : %5.3f Z : %5.3f", "X : %5.3f Z : %5.3f", "X : %5.3f Y : %5.3f",
      "X : %5.3f Y : %5.3f Z : %5.3f" };
   static const char* scaleInfoMask[] = { "X : %5.2f", "Y : %5.2f", "Z : %5.2f", "XYZ : %5.2f" };
   static const char* rotationInfoMask[] = { "X : %5.2f deg %5.2f rad", "Y : %5.2f deg %5.2f rad", "Z : %5.2f deg %5.2f rad", "Screen : %5.2f deg %5.2f rad" };
   static const int translationInfoIndex[] = { 0,0,0, 1,0,0, 2,0,0, 1,2,0, 0,2,0, 0,1,0, 0,1,2 };
   static const float quadMin = 0.5f;
   static const float quadMax = 0.8f;
   static const float quadUV[8] = { quadMin, quadMin, quadMin, quadMax, quadMax, quadMax, quadMax, quadMin };
   static const int halfCircleSegmentCount = 64;
   static const float snapTension = 0.5f;

   ///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
   //
   static int GetMoveType(vec_t* gizmoHitProportion);
   static int GetRotateType();
   static int GetScaleType();

   static ImVec2 worldToPos(const vec_t& worldPos, const matrix_t& mat, ImVec2 position = ImVec2(gContext.mX, gContext.mY), ImVec2 size = ImVec2(gContext.mWidth, gContext.mHeight))
   {
      vec_t trans;
      trans.TransformPoint(worldPos, mat);
      trans *= 0.5f / trans.w;
      trans += makeVect(0.5f, 0.5f);
      trans.y = 1.f - trans.y;
      trans.x *= size.x;
      trans.y *= size.y;
      trans.x += position.x;
      trans.y += position.y;
      return ImVec2(trans.x, trans.y);
   }

   static void ComputeCameraRay(vec_t& rayOrigin, vec_t& rayDir, ImVec2 position = ImVec2(gContext.mX, gContext.mY), ImVec2 size = ImVec2(gContext.mWidth, gContext.mHeight))
   {
      ImGuiIO& io = ImGui::GetIO();

      matrix_t mViewProjInverse;
      mViewProjInverse.Inverse(gContext.mViewMat * gContext.mProjectionMat);

      float mox = ((io.MousePos.x - position.x) / size.x) * 2.f - 1.f;
      float moy = (1.f - ((io.MousePos.y - position.y) / size.y)) * 2.f - 1.f;

      rayOrigin.Transform(makeVect(mox, moy, 0.f, 1.f), mViewProjInverse);
      rayOrigin *= 1.f / rayOrigin.w;
      vec_t rayEnd;
      rayEnd.Transform(makeVect(mox, moy, 1.f - FLT_EPSILON, 1.f), mViewProjInverse);
      rayEnd *= 1.f / rayEnd.w;
      rayDir = Normalized(rayEnd - rayOrigin);
   }

   static float GetSegmentLengthClipSpace(const vec_t& start, const vec_t& end)
   {
      vec_t startOfSegment = start;
      startOfSegment.TransformPoint(gContext.mMVP);
      if (fabsf(startOfSegment.w) > FLT_EPSILON) // check for axis aligned with camera direction
      {
         startOfSegment *= 1.f / startOfSegment.w;
      }

      vec_t endOfSegment = end;
      endOfSegment.TransformPoint(gContext.mMVP);
      if (fabsf(endOfSegment.w) > FLT_EPSILON) // check for axis aligned with camera direction
      {
         endOfSegment *= 1.f / endOfSegment.w;
      }

      vec_t clipSpaceAxis = endOfSegment - startOfSegment;
      clipSpaceAxis.y /= gContext.mDisplayRatio;
      float segmentLengthInClipSpace = sqrtf(clipSpaceAxis.x * clipSpaceAxis.x + clipSpaceAxis.y * clipSpaceAxis.y);
      return segmentLengthInClipSpace;
   }

   static float GetParallelogram(const vec_t& ptO, const vec_t& ptA, const vec_t& ptB)
   {
      vec_t pts[] = { ptO, ptA, ptB };
      for (unsigned int i = 0; i < 3; i++)
      {
         pts[i].TransformPoint(gContext.mMVP);
         if (fabsf(pts[i].w) > FLT_EPSILON) // check for axis aligned with camera direction
         {
            pts[i] *= 1.f / pts[i].w;
         }
      }
      vec_t segA = pts[1] - pts[0];
      vec_t segB = pts[2] - pts[0];
      segA.y /= gContext.mDisplayRatio;
      segB.y /= gContext.mDisplayRatio;
      vec_t segAOrtho = makeVect(-segA.y, segA.x);
      segAOrtho.Normalize();
      float dt = segAOrtho.Dot3(segB);
      float surface = sqrtf(segA.x * segA.x + segA.y * segA.y) * fabsf(dt);
      return surface;
   }

   inline vec_t PointOnSegment(const vec_t& point, const vec_t& vertPos1, const vec_t& vertPos2)
   {
      vec_t c = point - vertPos1;
      vec_t V;

      V.Normalize(vertPos2 - vertPos1);
      float d = (vertPos2 - vertPos1).Length();
      float t = V.Dot3(c);

      if (t < 0.f)
      {
         return vertPos1;
      }

      if (t > d)
      {
         return vertPos2;
      }

      return vertPos1 + V * t;
   }

   static float IntersectRayPlane(const vec_t& rOrigin, const vec_t& rVector, const vec_t& plan)
   {
      float numer = plan.Dot3(rOrigin) - plan.w;
      float denom = plan.Dot3(rVector);

      if (fabsf(denom) < FLT_EPSILON)  // normal is orthogonal to vector, cant intersect
      {
         return -1.0f;
      }

      return -(numer / denom);
   }

   static float DistanceToPlane(const vec_t& point, const vec_t& plan)
   {
      return plan.Dot3(point) + plan.w;
   }

   static bool IsInContextRect(ImVec2 p)
   {
      return IsWithin(p.x, gContext.mX, gContext.mXMax) && IsWithin(p.y, gContext.mY, gContext.mYMax);
   }

   void SetRect(float x, float y, float width, float height)
   {
      gContext.mX = x;
      gContext.mY = y;
      gContext.mWidth = width;
      gContext.mHeight = height;
      gContext.mXMax = gContext.mX + gContext.mWidth;
      gContext.mYMax = gContext.mY + gContext.mXMax;
      gContext.mDisplayRatio = width / height;
   }

   IMGUI_API void SetOrthographic(bool isOrthographic)
   {
      gContext.mIsOrthographic = isOrthographic;
   }

   void SetDrawlist(ImDrawList* drawlist)
   {
      gContext.mDrawList = drawlist ? drawlist : ImGui::GetWindowDrawList();
}

   void BeginFrame()
   {
      ImGuiIO& io = ImGui::GetIO();

      const ImU32 flags = ImGuiWindowFlags_NoTitleBar | ImGuiWindowFlags_NoResize | ImGuiWindowFlags_NoScrollbar | ImGuiWindowFlags_NoInputs | ImGuiWindowFlags_NoSavedSettings | ImGuiWindowFlags_NoFocusOnAppearing | ImGuiWindowFlags_NoBringToFrontOnFocus;

#ifdef IMGUI_HAS_VIEWPORT
      ImGui::SetNextWindowSize(ImGui::GetMainViewport()->Size);
      ImGui::SetNextWindowPos(ImGui::GetMainViewport()->Pos);
#else
      ImGui::SetNextWindowSize(io.DisplaySize);
      ImGui::SetNextWindowPos(ImVec2(0, 0));
#endif

      ImGui::PushStyleColor(ImGuiCol_WindowBg, 0);
      ImGui::PushStyleColor(ImGuiCol_Border, 0);
      ImGui::PushStyleVar(ImGuiStyleVar_WindowRounding, 0.0f);

      ImGui::Begin("gizmo", NULL, flags);
      gContext.mDrawList = ImGui::GetWindowDrawList();
      ImGui::End();
      ImGui::PopStyleVar();
      ImGui::PopStyleColor(2);
   }

   bool IsUsing()
   {
      return gContext.mbUsing || gContext.mbUsingBounds;
   }

   bool IsOver()
   {
      return (gContext.mOperation == TRANSLATE && GetMoveType(NULL) != NONE) ||
         (gContext.mOperation == ROTATE && GetRotateType() != NONE) ||
         (gContext.mOperation == SCALE && GetScaleType() != NONE) || IsUsing();
   }

   bool IsOver(OPERATION op) {
      switch (op) {
      case SCALE:       return GetScaleType()      != NONE || IsUsing();
      case ROTATE:      return GetRotateType()     != NONE || IsUsing();
      case TRANSLATE:   return GetMoveType(NULL)   != NONE || IsUsing();
      }
      return false;
   }

   void Enable(bool enable)
   {
      gContext.mbEnable = enable;
      if (!enable)
      {
         gContext.mbUsing = false;
         gContext.mbUsingBounds = false;
      }
   }

   static float GetUniform(const vec_t& position, const matrix_t& mat)
   {
      vec_t trf = makeVect(position.x, position.y, position.z, 1.f);
      trf.Transform(mat);
      return trf.w;
   }

   static void ComputeContext(const float* view, const float* projection, float* matrix, MODE mode)
   {
      gContext.mMode = mode;
      gContext.mViewMat = *(matrix_t*)view;
      gContext.mProjectionMat = *(matrix_t*)projection;

      if (mode == LOCAL)
      {
         gContext.mModel = *(matrix_t*)matrix;
         gContext.mModel.OrthoNormalize();
      }
      else
      {
         gContext.mModel.Translation(((matrix_t*)matrix)->v.position);
      }
      gContext.mModelSource = *(matrix_t*)matrix;
      gContext.mModelScaleOrigin.Set(gContext.mModelSource.v.right.Length(), gContext.mModelSource.v.up.Length(), gContext.mModelSource.v.dir.Length());

      gContext.mModelInverse.Inverse(gContext.mModel);
      gContext.mModelSourceInverse.Inverse(gContext.mModelSource);
      gContext.mViewProjection = gContext.mViewMat * gContext.mProjectionMat;
      gContext.mMVP = gContext.mModel * gContext.mViewProjection;

      matrix_t viewInverse;
      viewInverse.Inverse(gContext.mViewMat);
      gContext.mCameraDir = viewInverse.v.dir;
      gContext.mCameraEye = viewInverse.v.position;
      gContext.mCameraRight = viewInverse.v.right;
      gContext.mCameraUp = viewInverse.v.up;

      // compute scale from the size of camera right vector projected on screen at the matrix position
      vec_t pointRight = viewInverse.v.right;
      pointRight.TransformPoint(gContext.mViewProjection);
      gContext.mScreenFactor = gGizmoSizeClipSpace / (pointRight.x / pointRight.w - gContext.mMVP.v.position.x / gContext.mMVP.v.position.w);

      vec_t rightViewInverse = viewInverse.v.right;
      rightViewInverse.TransformVector(gContext.mModelInverse);
      float rightLength = GetSegmentLengthClipSpace(makeVect(0.f, 0.f), rightViewInverse);
      gContext.mScreenFactor = gGizmoSizeClipSpace / rightLength;

      ImVec2 centerSSpace = worldToPos(makeVect(0.f, 0.f), gContext.mMVP);
      gContext.mScreenSquareCenter = centerSSpace;
      gContext.mScreenSquareMin = ImVec2(centerSSpace.x - 10.f, centerSSpace.y - 10.f);
      gContext.mScreenSquareMax = ImVec2(centerSSpace.x + 10.f, centerSSpace.y + 10.f);

      ComputeCameraRay(gContext.mRayOrigin, gContext.mRayVector);
   }

   static void ComputeColors(ImU32* colors, int type, OPERATION operation)
   {
      if (gContext.mbEnable)
      {
         switch (operation)
         {
         case TRANSLATE:
            colors[0] = (type == MOVE_SCREEN) ? selectionColor : 0xFFFFFFFF;
            for (int i = 0; i < 3; i++)
            {
               colors[i + 1] = (type == (int)(MOVE_X + i)) ? selectionColor : directionColor[i];
               colors[i + 4] = (type == (int)(MOVE_YZ + i)) ? selectionColor : planeColor[i];
               colors[i + 4] = (type == MOVE_SCREEN) ? selectionColor : colors[i + 4];
            }
            break;
         case ROTATE:
            colors[0] = (type == ROTATE_SCREEN) ? selectionColor : 0xFFFFFFFF;
            for (int i = 0; i < 3; i++)
            {
               colors[i + 1] = (type == (int)(ROTATE_X + i)) ? selectionColor : directionColor[i];
            }
            break;
         case SCALE:
            colors[0] = (type == SCALE_XYZ) ? selectionColor : 0xFFFFFFFF;
            for (int i = 0; i < 3; i++)
            {
               colors[i + 1] = (type == (int)(SCALE_X + i)) ? selectionColor : directionColor[i];
            }
            break;
         case BOUNDS:
            break;
         }
      }
      else
      {
         for (int i = 0; i < 7; i++)
         {
            colors[i] = inactiveColor;
         }
      }
   }

   static void ComputeTripodAxisAndVisibility(int axisIndex, vec_t& dirAxis, vec_t& dirPlaneX, vec_t& dirPlaneY, bool& belowAxisLimit, bool& belowPlaneLimit)
   {
      dirAxis = directionUnary[axisIndex];
      dirPlaneX = directionUnary[(axisIndex + 1) % 3];
      dirPlaneY = directionUnary[(axisIndex + 2) % 3];

      if (gContext.mbUsing && (gContext.mActualID == -1 || gContext.mActualID == gContext.mEditingID))
      {
         // when using, use stored factors so the gizmo doesn't flip when we translate
         belowAxisLimit = gContext.mBelowAxisLimit[axisIndex];
         belowPlaneLimit = gContext.mBelowPlaneLimit[axisIndex];

         dirAxis *= gContext.mAxisFactor[axisIndex];
         dirPlaneX *= gContext.mAxisFactor[(axisIndex + 1) % 3];
         dirPlaneY *= gContext.mAxisFactor[(axisIndex + 2) % 3];
      }
      else
      {
         // new method
         float lenDir = GetSegmentLengthClipSpace(makeVect(0.f, 0.f, 0.f), dirAxis);
         float lenDirMinus = GetSegmentLengthClipSpace(makeVect(0.f, 0.f, 0.f), -dirAxis);

         float lenDirPlaneX = GetSegmentLengthClipSpace(makeVect(0.f, 0.f, 0.f), dirPlaneX);
         float lenDirMinusPlaneX = GetSegmentLengthClipSpace(makeVect(0.f, 0.f, 0.f), -dirPlaneX);

         float lenDirPlaneY = GetSegmentLengthClipSpace(makeVect(0.f, 0.f, 0.f), dirPlaneY);
         float lenDirMinusPlaneY = GetSegmentLengthClipSpace(makeVect(0.f, 0.f, 0.f), -dirPlaneY);

         float mulAxis = (lenDir < lenDirMinus && fabsf(lenDir - lenDirMinus) > FLT_EPSILON) ? -1.f : 1.f;
         float mulAxisX = (lenDirPlaneX < lenDirMinusPlaneX && fabsf(lenDirPlaneX - lenDirMinusPlaneX) > FLT_EPSILON) ? -1.f : 1.f;
         float mulAxisY = (lenDirPlaneY < lenDirMinusPlaneY && fabsf(lenDirPlaneY - lenDirMinusPlaneY) > FLT_EPSILON) ? -1.f : 1.f;
         dirAxis *= mulAxis;
         dirPlaneX *= mulAxisX;
         dirPlaneY *= mulAxisY;

         // for axis
         float axisLengthInClipSpace = GetSegmentLengthClipSpace(makeVect(0.f, 0.f, 0.f), dirAxis * gContext.mScreenFactor);

         float paraSurf = GetParallelogram(makeVect(0.f, 0.f, 0.f), dirPlaneX * gContext.mScreenFactor, dirPlaneY * gContext.mScreenFactor);
         belowPlaneLimit = (paraSurf > 0.0025f);
         belowAxisLimit = (axisLengthInClipSpace > 0.02f);

         // and store values
         gContext.mAxisFactor[axisIndex] = mulAxis;
         gContext.mAxisFactor[(axisIndex + 1) % 3] = mulAxisX;
         gContext.mAxisFactor[(axisIndex + 2) % 3] = mulAxisY;
         gContext.mBelowAxisLimit[axisIndex] = belowAxisLimit;
         gContext.mBelowPlaneLimit[axisIndex] = belowPlaneLimit;
      }
   }

   static void ComputeSnap(float* value, float snap)
   {
      if (snap <= FLT_EPSILON)
      {
         return;
      }

      float modulo = fmodf(*value, snap);
      float moduloRatio = fabsf(modulo) / snap;
      if (moduloRatio < snapTension)
      {
         *value -= modulo;
      }
      else if (moduloRatio > (1.f - snapTension))
      {
         *value = *value - modulo + snap * ((*value < 0.f) ? -1.f : 1.f);
      }
   }
   static void ComputeSnap(vec_t& value, float* snap)
   {
      for (int i = 0; i < 3; i++)
      {
         ComputeSnap(&value[i], snap[i]);
      }
   }

   static float ComputeAngleOnPlan()
   {
      const float len = IntersectRayPlane(gContext.mRayOrigin, gContext.mRayVector, gContext.mTranslationPlan);
      vec_t localPos = Normalized(gContext.mRayOrigin + gContext.mRayVector * len - gContext.mModel.v.position);

      vec_t perpendicularVector;
      perpendicularVector.Cross(gContext.mRotationVectorSource, gContext.mTranslationPlan);
      perpendicularVector.Normalize();
      float acosAngle = Clamp(Dot(localPos, gContext.mRotationVectorSource), -1.f, 1.f);
      float angle = acosf(acosAngle);
      angle *= (Dot(localPos, perpendicularVector) < 0.f) ? 1.f : -1.f;
      return angle;
   }

   static void DrawRotationGizmo(int type)
   {
      ImDrawList* drawList = gContext.mDrawList;

      // colors
      ImU32 colors[7];
      ComputeColors(colors, type, ROTATE);

      vec_t cameraToModelNormalized;
      if (gContext.mIsOrthographic)
      {
         matrix_t viewInverse;
         viewInverse.Inverse(*(matrix_t*)&gContext.mViewMat);
         cameraToModelNormalized = viewInverse.v.dir;
      }
      else
      {
         cameraToModelNormalized = Normalized(gContext.mModel.v.position - gContext.mCameraEye);
      }

      cameraToModelNormalized.TransformVector(gContext.mModelInverse);

      gContext.mRadiusSquareCenter = screenRotateSize * gContext.mHeight;

      for (int axis = 0; axis < 3; axis++)
      {
         ImVec2 circlePos[halfCircleSegmentCount];

         float angleStart = atan2f(cameraToModelNormalized[(4 - axis) % 3], cameraToModelNormalized[(3 - axis) % 3]) + ZPI * 0.5f;

         for (unsigned int i = 0; i < halfCircleSegmentCount; i++)
         {
            float ng = angleStart + ZPI * ((float)i / (float)halfCircleSegmentCount);
            vec_t axisPos = makeVect(cosf(ng), sinf(ng), 0.f);
            vec_t pos = makeVect(axisPos[axis], axisPos[(axis + 1) % 3], axisPos[(axis + 2) % 3]) * gContext.mScreenFactor;
            circlePos[i] = worldToPos(pos, gContext.mMVP);
         }

         float radiusAxis = sqrtf((ImLengthSqr(worldToPos(gContext.mModel.v.position, gContext.mViewProjection) - circlePos[0])));
         if (radiusAxis > gContext.mRadiusSquareCenter)
         {
            gContext.mRadiusSquareCenter = radiusAxis;
         }

         drawList->AddPolyline(circlePos, halfCircleSegmentCount, colors[3 - axis], false, 2);
      }
      drawList->AddCircle(worldToPos(gContext.mModel.v.position, gContext.mViewProjection), gContext.mRadiusSquareCenter, colors[0], 64, 3.f);

      if (gContext.mbUsing && (gContext.mActualID == -1 || gContext.mActualID == gContext.mEditingID))
      {
         ImVec2 circlePos[halfCircleSegmentCount + 1];

         circlePos[0] = worldToPos(gContext.mModel.v.position, gContext.mViewProjection);
         for (unsigned int i = 1; i < halfCircleSegmentCount; i++)
         {
            float ng = gContext.mRotationAngle * ((float)(i - 1) / (float)(halfCircleSegmentCount - 1));
            matrix_t rotateVectorMatrix;
            rotateVectorMatrix.RotationAxis(gContext.mTranslationPlan, ng);
            vec_t pos;
            pos.TransformPoint(gContext.mRotationVectorSource, rotateVectorMatrix);
            pos *= gContext.mScreenFactor;
            circlePos[i] = worldToPos(pos + gContext.mModel.v.position, gContext.mViewProjection);
         }
         drawList->AddConvexPolyFilled(circlePos, halfCircleSegmentCount, 0x801080FF);
         drawList->AddPolyline(circlePos, halfCircleSegmentCount, 0xFF1080FF, true, 2);

         ImVec2 destinationPosOnScreen = circlePos[1];
         char tmps[512];
         ImFormatString(tmps, sizeof(tmps), rotationInfoMask[type - ROTATE_X], (gContext.mRotationAngle / ZPI) * 180.f, gContext.mRotationAngle);
         drawList->AddText(ImVec2(destinationPosOnScreen.x + 15, destinationPosOnScreen.y + 15), 0xFF000000, tmps);
         drawList->AddText(ImVec2(destinationPosOnScreen.x + 14, destinationPosOnScreen.y + 14), 0xFFFFFFFF, tmps);
      }
   }

   static void DrawHatchedAxis(const vec_t& axis)
   {
      for (int j = 1; j < 10; j++)
      {
         ImVec2 baseSSpace2 = worldToPos(axis * 0.05f * (float)(j * 2) * gContext.mScreenFactor, gContext.mMVP);
         ImVec2 worldDirSSpace2 = worldToPos(axis * 0.05f * (float)(j * 2 + 1) * gContext.mScreenFactor, gContext.mMVP);
         gContext.mDrawList->AddLine(baseSSpace2, worldDirSSpace2, 0x80000000, 6.f);
      }
   }

   static void DrawScaleGizmo(int type)
   {
      ImDrawList* drawList = gContext.mDrawList;

      // colors
      ImU32 colors[7];
      ComputeColors(colors, type, SCALE);

      // draw
      vec_t scaleDisplay = { 1.f, 1.f, 1.f, 1.f };

      if (gContext.mbUsing && (gContext.mActualID == -1 || gContext.mActualID == gContext.mEditingID))
      {
         scaleDisplay = gContext.mScale;
      }

      for (unsigned int i = 0; i < 3; i++)
      {
         vec_t dirPlaneX, dirPlaneY, dirAxis;
         bool belowAxisLimit, belowPlaneLimit;
         ComputeTripodAxisAndVisibility(i, dirAxis, dirPlaneX, dirPlaneY, belowAxisLimit, belowPlaneLimit);

         // draw axis
         if (belowAxisLimit)
         {
            ImVec2 baseSSpace = worldToPos(dirAxis * 0.1f * gContext.mScreenFactor, gContext.mMVP);
            ImVec2 worldDirSSpaceNoScale = worldToPos(dirAxis * gContext.mScreenFactor, gContext.mMVP);
            ImVec2 worldDirSSpace = worldToPos((dirAxis * scaleDisplay[i]) * gContext.mScreenFactor, gContext.mMVP);

            if (gContext.mbUsing && (gContext.mActualID == -1 || gContext.mActualID == gContext.mEditingID))
            {
               drawList->AddLine(baseSSpace, worldDirSSpaceNoScale, 0xFF404040, 3.f);
               drawList->AddCircleFilled(worldDirSSpaceNoScale, 6.f, 0xFF404040);
            }

            drawList->AddLine(baseSSpace, worldDirSSpace, colors[i + 1], 3.f);
            drawList->AddCircleFilled(worldDirSSpace, 6.f, colors[i + 1]);

            if (gContext.mAxisFactor[i] < 0.f)
            {
               DrawHatchedAxis(dirAxis * scaleDisplay[i]);
            }
         }
      }

      // draw screen cirle
      drawList->AddCircleFilled(gContext.mScreenSquareCenter, 6.f, colors[0], 32);

      if (gContext.mbUsing && (gContext.mActualID == -1 || gContext.mActualID == gContext.mEditingID))
      {
         //ImVec2 sourcePosOnScreen = worldToPos(gContext.mMatrixOrigin, gContext.mViewProjection);
         ImVec2 destinationPosOnScreen = worldToPos(gContext.mModel.v.position, gContext.mViewProjection);
         /*vec_t dif(destinationPosOnScreen.x - sourcePosOnScreen.x, destinationPosOnScreen.y - sourcePosOnScreen.y);
         dif.Normalize();
         dif *= 5.f;
         drawList->AddCircle(sourcePosOnScreen, 6.f, translationLineColor);
         drawList->AddCircle(destinationPosOnScreen, 6.f, translationLineColor);
         drawList->AddLine(ImVec2(sourcePosOnScreen.x + dif.x, sourcePosOnScreen.y + dif.y), ImVec2(destinationPosOnScreen.x - dif.x, destinationPosOnScreen.y - dif.y), translationLineColor, 2.f);
         */
         char tmps[512];
         //vec_t deltaInfo = gContext.mModel.v.position - gContext.mMatrixOrigin;
         int componentInfoIndex = (type - SCALE_X) * 3;
         ImFormatString(tmps, sizeof(tmps), scaleInfoMask[type - SCALE_X], scaleDisplay[translationInfoIndex[componentInfoIndex]]);
         drawList->AddText(ImVec2(destinationPosOnScreen.x + 15, destinationPosOnScreen.y + 15), 0xFF000000, tmps);
         drawList->AddText(ImVec2(destinationPosOnScreen.x + 14, destinationPosOnScreen.y + 14), 0xFFFFFFFF, tmps);
      }
   }


   static void DrawTranslationGizmo(int type)
   {
      ImDrawList* drawList = gContext.mDrawList;
      if (!drawList)
      {
         return;
      }

      // colors
      ImU32 colors[7];
      ComputeColors(colors, type, TRANSLATE);

      const ImVec2 origin = worldToPos(gContext.mModel.v.position, gContext.mViewProjection);

      // draw
      bool belowAxisLimit = false;
      bool belowPlaneLimit = false;
      for (unsigned int i = 0; i < 3; ++i)
      {
         vec_t dirPlaneX, dirPlaneY, dirAxis;
         ComputeTripodAxisAndVisibility(i, dirAxis, dirPlaneX, dirPlaneY, belowAxisLimit, belowPlaneLimit);

         // draw axis
         if (belowAxisLimit)
         {
            ImVec2 baseSSpace = worldToPos(dirAxis * 0.1f * gContext.mScreenFactor, gContext.mMVP);
            ImVec2 worldDirSSpace = worldToPos(dirAxis * gContext.mScreenFactor, gContext.mMVP);

            drawList->AddLine(baseSSpace, worldDirSSpace, colors[i + 1], 3.f);

            // Arrow head begin
            ImVec2 dir(origin - worldDirSSpace);

            float d = sqrtf(ImLengthSqr(dir));
            dir /= d; // Normalize
            dir *= 6.0f;

            ImVec2 ortogonalDir(dir.y, -dir.x); // Perpendicular vector
            ImVec2 a(worldDirSSpace + dir);
            drawList->AddTriangleFilled(worldDirSSpace - dir, a + ortogonalDir, a - ortogonalDir, colors[i + 1]);
            // Arrow head end

            if (gContext.mAxisFactor[i] < 0.f)
            {
               DrawHatchedAxis(dirAxis);
            }
         }

         // draw plane
         if (belowPlaneLimit)
         {
            ImVec2 screenQuadPts[4];
            for (int j = 0; j < 4; ++j)
            {
               vec_t cornerWorldPos = (dirPlaneX * quadUV[j * 2] + dirPlaneY * quadUV[j * 2 + 1]) * gContext.mScreenFactor;
               screenQuadPts[j] = worldToPos(cornerWorldPos, gContext.mMVP);
            }
            drawList->AddPolyline(screenQuadPts, 4, directionColor[i], true, 1.0f);
            drawList->AddConvexPolyFilled(screenQuadPts, 4, colors[i + 4]);
         }
      }

      drawList->AddCircleFilled(gContext.mScreenSquareCenter, 6.f, colors[0], 32);

      if (gContext.mbUsing && (gContext.mActualID == -1 || gContext.mActualID == gContext.mEditingID))
      {
         ImVec2 sourcePosOnScreen = worldToPos(gContext.mMatrixOrigin, gContext.mViewProjection);
         ImVec2 destinationPosOnScreen = worldToPos(gContext.mModel.v.position, gContext.mViewProjection);
         vec_t dif = { destinationPosOnScreen.x - sourcePosOnScreen.x, destinationPosOnScreen.y - sourcePosOnScreen.y, 0.f, 0.f };
         dif.Normalize();
         dif *= 5.f;
         drawList->AddCircle(sourcePosOnScreen, 6.f, translationLineColor);
         drawList->AddCircle(destinationPosOnScreen, 6.f, translationLineColor);
         drawList->AddLine(ImVec2(sourcePosOnScreen.x + dif.x, sourcePosOnScreen.y + dif.y), ImVec2(destinationPosOnScreen.x - dif.x, destinationPosOnScreen.y - dif.y), translationLineColor, 2.f);

         char tmps[512];
         vec_t deltaInfo = gContext.mModel.v.position - gContext.mMatrixOrigin;
         int componentInfoIndex = (type - MOVE_X) * 3;
         ImFormatString(tmps, sizeof(tmps), translationInfoMask[type - MOVE_X], deltaInfo[translationInfoIndex[componentInfoIndex]], deltaInfo[translationInfoIndex[componentInfoIndex + 1]], deltaInfo[translationInfoIndex[componentInfoIndex + 2]]);
         drawList->AddText(ImVec2(destinationPosOnScreen.x + 15, destinationPosOnScreen.y + 15), 0xFF000000, tmps);
         drawList->AddText(ImVec2(destinationPosOnScreen.x + 14, destinationPosOnScreen.y + 14), 0xFFFFFFFF, tmps);
      }
   }

   static bool CanActivate()
   {
      if (ImGui::IsMouseClicked(0) && !ImGui::IsAnyItemHovered() && !ImGui::IsAnyItemActive())
      {
         return true;
      }
      return false;
   }

   static void HandleAndDrawLocalBounds(float* bounds, matrix_t* matrix, float* snapValues, OPERATION operation)
   {
      ImGuiIO& io = ImGui::GetIO();
      ImDrawList* drawList = gContext.mDrawList;

      // compute best projection axis
      vec_t axesWorldDirections[3];
      vec_t bestAxisWorldDirection = { 0.0f, 0.0f, 0.0f, 0.0f };
      int axes[3];
      unsigned int numAxes = 1;
      axes[0] = gContext.mBoundsBestAxis;
      int bestAxis = axes[0];
      if (!gContext.mbUsingBounds)
      {
         numAxes = 0;
         float bestDot = 0.f;
         for (unsigned int i = 0; i < 3; i++)
         {
            vec_t dirPlaneNormalWorld;
            dirPlaneNormalWorld.TransformVector(directionUnary[i], gContext.mModelSource);
            dirPlaneNormalWorld.Normalize();

            float dt = fabsf(Dot(Normalized(gContext.mCameraEye - gContext.mModelSource.v.position), dirPlaneNormalWorld));
            if (dt >= bestDot)
            {
               bestDot = dt;
               bestAxis = i;
               bestAxisWorldDirection = dirPlaneNormalWorld;
            }

            if (dt >= 0.1f)
            {
               axes[numAxes] = i;
               axesWorldDirections[numAxes] = dirPlaneNormalWorld;
               ++numAxes;
            }
         }
      }

      if (numAxes == 0)
      {
         axes[0] = bestAxis;
         axesWorldDirections[0] = bestAxisWorldDirection;
         numAxes = 1;
      }

      else if (bestAxis != axes[0])
      {
         unsigned int bestIndex = 0;
         for (unsigned int i = 0; i < numAxes; i++)
         {
            if (axes[i] == bestAxis)
            {
               bestIndex = i;
               break;
            }
         }
         int tempAxis = axes[0];
         axes[0] = axes[bestIndex];
         axes[bestIndex] = tempAxis;
         vec_t tempDirection = axesWorldDirections[0];
         axesWorldDirections[0] = axesWorldDirections[bestIndex];
         axesWorldDirections[bestIndex] = tempDirection;
      }

      for (unsigned int axisIndex = 0; axisIndex < numAxes; ++axisIndex)
      {
         bestAxis = axes[axisIndex];
         bestAxisWorldDirection = axesWorldDirections[axisIndex];

         // corners
         vec_t aabb[4];

         int secondAxis = (bestAxis + 1) % 3;
         int thirdAxis = (bestAxis + 2) % 3;

         for (int i = 0; i < 4; i++)
         {
            aabb[i][3] = aabb[i][bestAxis] = 0.f;
            aabb[i][secondAxis] = bounds[secondAxis + 3 * (i >> 1)];
            aabb[i][thirdAxis] = bounds[thirdAxis + 3 * ((i >> 1) ^ (i & 1))];
         }

         // draw bounds
         unsigned int anchorAlpha = gContext.mbEnable ? 0xFF000000 : 0x80000000;

         matrix_t boundsMVP = gContext.mModelSource * gContext.mViewProjection;
         for (int i = 0; i < 4; i++)
         {
            ImVec2 worldBound1 = worldToPos(aabb[i], boundsMVP);
            ImVec2 worldBound2 = worldToPos(aabb[(i + 1) % 4], boundsMVP);
            if (!IsInContextRect(worldBound1) || !IsInContextRect(worldBound2))
            {
               continue;
            }
            float boundDistance = sqrtf(ImLengthSqr(worldBound1 - worldBound2));
            int stepCount = (int)(boundDistance / 10.f);
            stepCount = min(stepCount, 1000);
            float stepLength = 1.f / (float)stepCount;
            for (int j = 0; j < stepCount; j++)
            {
               float t1 = (float)j * stepLength;
               float t2 = (float)j * stepLength + stepLength * 0.5f;
               ImVec2 worldBoundSS1 = ImLerp(worldBound1, worldBound2, ImVec2(t1, t1));
               ImVec2 worldBoundSS2 = ImLerp(worldBound1, worldBound2, ImVec2(t2, t2));
               //drawList->AddLine(worldBoundSS1, worldBoundSS2, 0x000000 + anchorAlpha, 3.f);
               drawList->AddLine(worldBoundSS1, worldBoundSS2, 0xAAAAAA + anchorAlpha, 2.f);
            }
            vec_t midPoint = (aabb[i] + aabb[(i + 1) % 4]) * 0.5f;
            ImVec2 midBound = worldToPos(midPoint, boundsMVP);
            static const float AnchorBigRadius = 8.f;
            static const float AnchorSmallRadius = 6.f;
            bool overBigAnchor = ImLengthSqr(worldBound1 - io.MousePos) <= (AnchorBigRadius * AnchorBigRadius);
            bool overSmallAnchor = ImLengthSqr(midBound - io.MousePos) <= (AnchorBigRadius * AnchorBigRadius);

            int type = NONE;
            vec_t gizmoHitProportion;

            switch (operation)
            {
               case TRANSLATE: type = GetMoveType(&gizmoHitProportion); break;
               case ROTATE: type = GetRotateType(); break;
               case SCALE: type = GetScaleType(); break;
               case BOUNDS: break;
            }
            if (type != NONE)
            {
               overBigAnchor = false;
               overSmallAnchor = false;
            }

            unsigned int bigAnchorColor = overBigAnchor ? selectionColor : (0xAAAAAA + anchorAlpha);
            unsigned int smallAnchorColor = overSmallAnchor ? selectionColor : (0xAAAAAA + anchorAlpha);

            drawList->AddCircleFilled(worldBound1, AnchorBigRadius, 0xFF000000);
            drawList->AddCircleFilled(worldBound1, AnchorBigRadius - 1.2f, bigAnchorColor);

            drawList->AddCircleFilled(midBound, AnchorSmallRadius, 0xFF000000);
            drawList->AddCircleFilled(midBound, AnchorSmallRadius - 1.2f, smallAnchorColor);
            int oppositeIndex = (i + 2) % 4;
            // big anchor on corners
            if (!gContext.mbUsingBounds && gContext.mbEnable && overBigAnchor && CanActivate())
            {
               gContext.mBoundsPivot.TransformPoint(aabb[(i + 2) % 4], gContext.mModelSource);
               gContext.mBoundsAnchor.TransformPoint(aabb[i], gContext.mModelSource);
               gContext.mBoundsPlan = BuildPlan(gContext.mBoundsAnchor, bestAxisWorldDirection);
               gContext.mBoundsBestAxis = bestAxis;
               gContext.mBoundsAxis[0] = secondAxis;
               gContext.mBoundsAxis[1] = thirdAxis;

               gContext.mBoundsLocalPivot.Set(0.f);
               gContext.mBoundsLocalPivot[secondAxis] = aabb[oppositeIndex][secondAxis];
               gContext.mBoundsLocalPivot[thirdAxis] = aabb[oppositeIndex][thirdAxis];

               gContext.mbUsingBounds = true;
               gContext.mEditingID = gContext.mActualID;
               gContext.mBoundsMatrix = gContext.mModelSource;
            }
            // small anchor on middle of segment
            if (!gContext.mbUsingBounds && gContext.mbEnable && overSmallAnchor && CanActivate())
            {
               vec_t midPointOpposite = (aabb[(i + 2) % 4] + aabb[(i + 3) % 4]) * 0.5f;
               gContext.mBoundsPivot.TransformPoint(midPointOpposite, gContext.mModelSource);
               gContext.mBoundsAnchor.TransformPoint(midPoint, gContext.mModelSource);
               gContext.mBoundsPlan = BuildPlan(gContext.mBoundsAnchor, bestAxisWorldDirection);
               gContext.mBoundsBestAxis = bestAxis;
               int indices[] = { secondAxis , thirdAxis };
               gContext.mBoundsAxis[0] = indices[i % 2];
               gContext.mBoundsAxis[1] = -1;

               gContext.mBoundsLocalPivot.Set(0.f);
               gContext.mBoundsLocalPivot[gContext.mBoundsAxis[0]] = aabb[oppositeIndex][indices[i % 2]];// bounds[gContext.mBoundsAxis[0]] * (((i + 1) & 2) ? 1.f : -1.f);

               gContext.mbUsingBounds = true;
               gContext.mEditingID = gContext.mActualID;
               gContext.mBoundsMatrix = gContext.mModelSource;
            }
         }

         if (gContext.mbUsingBounds && (gContext.mActualID == -1 || gContext.mActualID == gContext.mEditingID))
         {
            matrix_t scale;
            scale.SetToIdentity();

            // compute projected mouse position on plan
            const float len = IntersectRayPlane(gContext.mRayOrigin, gContext.mRayVector, gContext.mBoundsPlan);
            vec_t newPos = gContext.mRayOrigin + gContext.mRayVector * len;

            // compute a reference and delta vectors base on mouse move
            vec_t deltaVector = (newPos - gContext.mBoundsPivot).Abs();
            vec_t referenceVector = (gContext.mBoundsAnchor - gContext.mBoundsPivot).Abs();

            // for 1 or 2 axes, compute a ratio that's used for scale and snap it based on resulting length
            for (int i = 0; i < 2; i++)
            {
               int axisIndex1 = gContext.mBoundsAxis[i];
               if (axisIndex1 == -1)
               {
                  continue;
               }

               float ratioAxis = 1.f;
               vec_t axisDir = gContext.mBoundsMatrix.component[axisIndex1].Abs();

               float dtAxis = axisDir.Dot(referenceVector);
               float boundSize = bounds[axisIndex1 + 3] - bounds[axisIndex1];
               if (dtAxis > FLT_EPSILON)
               {
                  ratioAxis = axisDir.Dot(deltaVector) / dtAxis;
               }

               if (snapValues)
               {
                  float length = boundSize * ratioAxis;
                  ComputeSnap(&length, snapValues[axisIndex1]);
                  if (boundSize > FLT_EPSILON)
                  {
                     ratioAxis = length / boundSize;
                  }
               }
               scale.component[axisIndex1] *= ratioAxis;
            }

            // transform matrix
            matrix_t preScale, postScale;
            preScale.Translation(-gContext.mBoundsLocalPivot);
            postScale.Translation(gContext.mBoundsLocalPivot);
            matrix_t res = preScale * scale * postScale * gContext.mBoundsMatrix;
            *matrix = res;

            // info text
            char tmps[512];
            ImVec2 destinationPosOnScreen = worldToPos(gContext.mModel.v.position, gContext.mViewProjection);
            ImFormatString(tmps, sizeof(tmps), "X: %.2f Y: %.2f Z:%.2f"
               , (bounds[3] - bounds[0]) * gContext.mBoundsMatrix.component[0].Length() * scale.component[0].Length()
               , (bounds[4] - bounds[1]) * gContext.mBoundsMatrix.component[1].Length() * scale.component[1].Length()
               , (bounds[5] - bounds[2]) * gContext.mBoundsMatrix.component[2].Length() * scale.component[2].Length()
            );
            drawList->AddText(ImVec2(destinationPosOnScreen.x + 15, destinationPosOnScreen.y + 15), 0xFF000000, tmps);
            drawList->AddText(ImVec2(destinationPosOnScreen.x + 14, destinationPosOnScreen.y + 14), 0xFFFFFFFF, tmps);
         }

         if (!io.MouseDown[0]) {
            gContext.mbUsingBounds = false;
            gContext.mEditingID = -1;
         }
         if (gContext.mbUsingBounds)
         {
            break;
         }
      }
   }

   ///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
   //

   static int GetScaleType()
   {
      ImGuiIO& io = ImGui::GetIO();
      int type = NONE;

      // screen
      if (io.MousePos.x >= gContext.mScreenSquareMin.x && io.MousePos.x <= gContext.mScreenSquareMax.x &&
         io.MousePos.y >= gContext.mScreenSquareMin.y && io.MousePos.y <= gContext.mScreenSquareMax.y)
      {
         type = SCALE_XYZ;
      }

      // compute
      for (unsigned int i = 0; i < 3 && type == NONE; i++)
      {
         vec_t dirPlaneX, dirPlaneY, dirAxis;
         bool belowAxisLimit, belowPlaneLimit;
         ComputeTripodAxisAndVisibility(i, dirAxis, dirPlaneX, dirPlaneY, belowAxisLimit, belowPlaneLimit);
         dirAxis.TransformVector(gContext.mModel);
         dirPlaneX.TransformVector(gContext.mModel);
         dirPlaneY.TransformVector(gContext.mModel);

         const float len = IntersectRayPlane(gContext.mRayOrigin, gContext.mRayVector, BuildPlan(gContext.mModel.v.position, dirAxis));
         vec_t posOnPlan = gContext.mRayOrigin + gContext.mRayVector * len;

         const ImVec2 posOnPlanScreen = worldToPos(posOnPlan, gContext.mViewProjection);
         const ImVec2 axisStartOnScreen = worldToPos(gContext.mModel.v.position + dirAxis * gContext.mScreenFactor * 0.1f, gContext.mViewProjection);
         const ImVec2 axisEndOnScreen = worldToPos(gContext.mModel.v.position + dirAxis * gContext.mScreenFactor, gContext.mViewProjection);

         vec_t closestPointOnAxis = PointOnSegment(makeVect(posOnPlanScreen), makeVect(axisStartOnScreen), makeVect(axisEndOnScreen));

         if ((closestPointOnAxis - makeVect(posOnPlanScreen)).Length() < 12.f) // pixel size
         {
            type = SCALE_X + i;
         }
      }
      return type;
   }

   static int GetRotateType()
   {
      ImGuiIO& io = ImGui::GetIO();
      int type = NONE;

      vec_t deltaScreen = { io.MousePos.x - gContext.mScreenSquareCenter.x, io.MousePos.y - gContext.mScreenSquareCenter.y, 0.f, 0.f };
      float dist = deltaScreen.Length();
      if (dist >= (gContext.mRadiusSquareCenter - 1.0f) && dist < (gContext.mRadiusSquareCenter + 1.0f))
      {
         type = ROTATE_SCREEN;
      }

      const vec_t planNormals[] = { gContext.mModel.v.right, gContext.mModel.v.up, gContext.mModel.v.dir };

      for (unsigned int i = 0; i < 3 && type == NONE; i++)
      {
         // pickup plan
         vec_t pickupPlan = BuildPlan(gContext.mModel.v.position, planNormals[i]);

         const float len = IntersectRayPlane(gContext.mRayOrigin, gContext.mRayVector, pickupPlan);
         vec_t localPos = gContext.mRayOrigin + gContext.mRayVector * len - gContext.mModel.v.position;

         if (Dot(Normalized(localPos), gContext.mRayVector) > FLT_EPSILON)
         {
            continue;
         }
         vec_t idealPosOnCircle = Normalized(localPos);
         idealPosOnCircle.TransformVector(gContext.mModelInverse);
         ImVec2 idealPosOnCircleScreen = worldToPos(idealPosOnCircle * gContext.mScreenFactor, gContext.mMVP);

         //gContext.mDrawList->AddCircle(idealPosOnCircleScreen, 5.f, 0xFFFFFFFF);
         ImVec2 distanceOnScreen = idealPosOnCircleScreen - io.MousePos;

         float distance = makeVect(distanceOnScreen).Length();
         if (distance < 8.f) // pixel size
         {
            type = ROTATE_X + i;
         }
      }

      return type;
   }

   static int GetMoveType(vec_t* gizmoHitProportion)
   {
      ImGuiIO& io = ImGui::GetIO();
      int type = NONE;

      // screen
      if (io.MousePos.x >= gContext.mScreenSquareMin.x && io.MousePos.x <= gContext.mScreenSquareMax.x &&
         io.MousePos.y >= gContext.mScreenSquareMin.y && io.MousePos.y <= gContext.mScreenSquareMax.y)
      {
         type = MOVE_SCREEN;
      }

      // compute
      for (unsigned int i = 0; i < 3 && type == NONE; i++)
      {
         vec_t dirPlaneX, dirPlaneY, dirAxis;
         bool belowAxisLimit, belowPlaneLimit;
         ComputeTripodAxisAndVisibility(i, dirAxis, dirPlaneX, dirPlaneY, belowAxisLimit, belowPlaneLimit);
         dirAxis.TransformVector(gContext.mModel);
         dirPlaneX.TransformVector(gContext.mModel);
         dirPlaneY.TransformVector(gContext.mModel);

         const float len = IntersectRayPlane(gContext.mRayOrigin, gContext.mRayVector, BuildPlan(gContext.mModel.v.position, dirAxis));
         vec_t posOnPlan = gContext.mRayOrigin + gContext.mRayVector * len;

         const ImVec2 posOnPlanScreen = worldToPos(posOnPlan, gContext.mViewProjection);
         const ImVec2 axisStartOnScreen = worldToPos(gContext.mModel.v.position + dirAxis * gContext.mScreenFactor * 0.1f, gContext.mViewProjection);
         const ImVec2 axisEndOnScreen = worldToPos(gContext.mModel.v.position + dirAxis * gContext.mScreenFactor, gContext.mViewProjection);

         vec_t closestPointOnAxis = PointOnSegment(makeVect(posOnPlanScreen), makeVect(axisStartOnScreen), makeVect(axisEndOnScreen));

         if ((closestPointOnAxis - makeVect(posOnPlanScreen)).Length() < 12.f) // pixel size
         {
            type = MOVE_X + i;
         }

         const float dx = dirPlaneX.Dot3((posOnPlan - gContext.mModel.v.position) * (1.f / gContext.mScreenFactor));
         const float dy = dirPlaneY.Dot3((posOnPlan - gContext.mModel.v.position) * (1.f / gContext.mScreenFactor));
         if (belowPlaneLimit && dx >= quadUV[0] && dx <= quadUV[4] && dy >= quadUV[1] && dy <= quadUV[3])
         {
            type = MOVE_YZ + i;
         }

         if (gizmoHitProportion)
         {
            *gizmoHitProportion = makeVect(dx, dy, 0.f);
         }
      }
      return type;
   }

   static bool HandleTranslation(float* matrix, float* deltaMatrix, int& type, float* snap)
   {
      ImGuiIO& io = ImGui::GetIO();
      bool applyRotationLocaly = gContext.mMode == LOCAL || type == MOVE_SCREEN;
      bool modified = false;

      // move
      if (gContext.mbUsing && (gContext.mActualID == -1 || gContext.mActualID == gContext.mEditingID))
      {
         ImGui::CaptureMouseFromApp();
         const float len = fabsf(IntersectRayPlane(gContext.mRayOrigin, gContext.mRayVector, gContext.mTranslationPlan)); // near plan
         vec_t newPos = gContext.mRayOrigin + gContext.mRayVector * len;

         // compute delta
         vec_t newOrigin = newPos - gContext.mRelativeOrigin * gContext.mScreenFactor;
         vec_t delta = newOrigin - gContext.mModel.v.position;

         // 1 axis constraint
         if (gContext.mCurrentOperation >= MOVE_X && gContext.mCurrentOperation <= MOVE_Z)
         {
            int axisIndex = gContext.mCurrentOperation - MOVE_X;
            const vec_t& axisValue = *(vec_t*)&gContext.mModel.m[axisIndex];
            float lengthOnAxis = Dot(axisValue, delta);
            delta = axisValue * lengthOnAxis;
         }

         // snap
         if (snap)
         {
            vec_t cumulativeDelta = gContext.mModel.v.position + delta - gContext.mMatrixOrigin;
            if (applyRotationLocaly)
            {
               matrix_t modelSourceNormalized = gContext.mModelSource;
               modelSourceNormalized.OrthoNormalize();
               matrix_t modelSourceNormalizedInverse;
               modelSourceNormalizedInverse.Inverse(modelSourceNormalized);
               cumulativeDelta.TransformVector(modelSourceNormalizedInverse);
               ComputeSnap(cumulativeDelta, snap);
               cumulativeDelta.TransformVector(modelSourceNormalized);
            }
            else
            {
               ComputeSnap(cumulativeDelta, snap);
            }
            delta = gContext.mMatrixOrigin + cumulativeDelta - gContext.mModel.v.position;

         }

         if(delta != gContext.mTranslationLastDelta)
         {
             modified = true;
         }
         gContext.mTranslationLastDelta = delta;

         // compute matrix & delta
         matrix_t deltaMatrixTranslation;
         deltaMatrixTranslation.Translation(delta);
         if (deltaMatrix)
         {
            memcpy(deltaMatrix, deltaMatrixTranslation.m16, sizeof(float) * 16);
         }

         matrix_t res = gContext.mModelSource * deltaMatrixTranslation;
         *(matrix_t*)matrix = res;

         if (!io.MouseDown[0])
         {
            gContext.mbUsing = false;
         }

         type = gContext.mCurrentOperation;
      }
      else
      {
         // find new possible way to move
         vec_t gizmoHitProportion;
         type = GetMoveType(&gizmoHitProportion);
         if (type != NONE)
         {
            ImGui::CaptureMouseFromApp();
         }
         if (CanActivate() && type != NONE)
         {
            gContext.mbUsing = true;
            gContext.mEditingID = gContext.mActualID;
            gContext.mCurrentOperation = type;
            vec_t movePlanNormal[] = { gContext.mModel.v.right, gContext.mModel.v.up, gContext.mModel.v.dir,
               gContext.mModel.v.right, gContext.mModel.v.up, gContext.mModel.v.dir,
               -gContext.mCameraDir };

            vec_t cameraToModelNormalized = Normalized(gContext.mModel.v.position - gContext.mCameraEye);
            for (unsigned int i = 0; i < 3; i++)
            {
               vec_t orthoVector = Cross(movePlanNormal[i], cameraToModelNormalized);
               movePlanNormal[i].Cross(orthoVector);
               movePlanNormal[i].Normalize();
            }
            // pickup plan
            gContext.mTranslationPlan = BuildPlan(gContext.mModel.v.position, movePlanNormal[type - MOVE_X]);
            const float len = IntersectRayPlane(gContext.mRayOrigin, gContext.mRayVector, gContext.mTranslationPlan);
            gContext.mTranslationPlanOrigin = gContext.mRayOrigin + gContext.mRayVector * len;
            gContext.mMatrixOrigin = gContext.mModel.v.position;

            gContext.mRelativeOrigin = (gContext.mTranslationPlanOrigin - gContext.mModel.v.position) * (1.f / gContext.mScreenFactor);
         }
      }
      return modified;
   }

   static bool HandleScale(float* matrix, float* deltaMatrix, int& type, float* snap)
   {
      ImGuiIO& io = ImGui::GetIO();
      bool modified = false;

      if (!gContext.mbUsing)
      {
         // find new possible way to scale
         type = GetScaleType();
         if (type != NONE)
         {
            ImGui::CaptureMouseFromApp();
         }
         if (CanActivate() && type != NONE)
         {
            gContext.mbUsing = true;
            gContext.mEditingID = gContext.mActualID;
            gContext.mCurrentOperation = type;
            const vec_t movePlanNormal[] = { gContext.mModel.v.up, gContext.mModel.v.dir, gContext.mModel.v.right, gContext.mModel.v.dir, gContext.mModel.v.up, gContext.mModel.v.right, -gContext.mCameraDir };
            // pickup plan

            gContext.mTranslationPlan = BuildPlan(gContext.mModel.v.position, movePlanNormal[type - SCALE_X]);
            const float len = IntersectRayPlane(gContext.mRayOrigin, gContext.mRayVector, gContext.mTranslationPlan);
            gContext.mTranslationPlanOrigin = gContext.mRayOrigin + gContext.mRayVector * len;
            gContext.mMatrixOrigin = gContext.mModel.v.position;
            gContext.mScale.Set(1.f, 1.f, 1.f);
            gContext.mRelativeOrigin = (gContext.mTranslationPlanOrigin - gContext.mModel.v.position) * (1.f / gContext.mScreenFactor);
            gContext.mScaleValueOrigin = makeVect(gContext.mModelSource.v.right.Length(), gContext.mModelSource.v.up.Length(), gContext.mModelSource.v.dir.Length());
            gContext.mSaveMousePosx = io.MousePos.x;
         }
      }
      // scale
      if (gContext.mbUsing && (gContext.mActualID == -1 || gContext.mActualID == gContext.mEditingID))
      {
         ImGui::CaptureMouseFromApp();
         const float len = IntersectRayPlane(gContext.mRayOrigin, gContext.mRayVector, gContext.mTranslationPlan);
         vec_t newPos = gContext.mRayOrigin + gContext.mRayVector * len;
         vec_t newOrigin = newPos - gContext.mRelativeOrigin * gContext.mScreenFactor;
         vec_t delta = newOrigin - gContext.mModel.v.position;

         // 1 axis constraint
         if (gContext.mCurrentOperation >= SCALE_X && gContext.mCurrentOperation <= SCALE_Z)
         {
            int axisIndex = gContext.mCurrentOperation - SCALE_X;
            const vec_t& axisValue = *(vec_t*)&gContext.mModel.m[axisIndex];
            float lengthOnAxis = Dot(axisValue, delta);
            delta = axisValue * lengthOnAxis;

            vec_t baseVector = gContext.mTranslationPlanOrigin - gContext.mModel.v.position;
            float ratio = Dot(axisValue, baseVector + delta) / Dot(axisValue, baseVector);

            gContext.mScale[axisIndex] = max(ratio, 0.001f);
         }
         else
         {
            float scaleDelta = (io.MousePos.x - gContext.mSaveMousePosx) * 0.01f;
            gContext.mScale.Set(max(1.f + scaleDelta, 0.001f));
         }

         // snap
         if (snap)
         {
            float scaleSnap[] = { snap[0], snap[0], snap[0] };
            ComputeSnap(gContext.mScale, scaleSnap);
         }

         // no 0 allowed
         for (int i = 0; i < 3; i++)
            gContext.mScale[i] = max(gContext.mScale[i], 0.001f);

         if(gContext.mScaleLast != gContext.mScale)
         {
             modified = true;
         }
         gContext.mScaleLast = gContext.mScale;

         // compute matrix & delta
         matrix_t deltaMatrixScale;
         deltaMatrixScale.Scale(gContext.mScale * gContext.mScaleValueOrigin);

         matrix_t res = deltaMatrixScale * gContext.mModel;
         *(matrix_t*)matrix = res;

         if (deltaMatrix)
         {
            deltaMatrixScale.Scale(gContext.mScale);
            memcpy(deltaMatrix, deltaMatrixScale.m16, sizeof(float) * 16);
         }

         if (!io.MouseDown[0])
            gContext.mbUsing = false;

         type = gContext.mCurrentOperation;
      }
      return modified;
   }

   static bool HandleRotation(float* matrix, float* deltaMatrix, int& type, float* snap)
   {
      ImGuiIO& io = ImGui::GetIO();
      bool applyRotationLocaly = gContext.mMode == LOCAL;
      bool modified = false;

      if (!gContext.mbUsing)
      {
         type = GetRotateType();

         if (type != NONE)
         {
            ImGui::CaptureMouseFromApp();
         }

         if (type == ROTATE_SCREEN)
         {
            applyRotationLocaly = true;
         }

         if (CanActivate() && type != NONE)
         {
            gContext.mbUsing = true;
            gContext.mEditingID = gContext.mActualID;
            gContext.mCurrentOperation = type;
            const vec_t rotatePlanNormal[] = { gContext.mModel.v.right, gContext.mModel.v.up, gContext.mModel.v.dir, -gContext.mCameraDir };
            // pickup plan
            if (applyRotationLocaly)
            {
               gContext.mTranslationPlan = BuildPlan(gContext.mModel.v.position, rotatePlanNormal[type - ROTATE_X]);
            }
            else
            {
               gContext.mTranslationPlan = BuildPlan(gContext.mModelSource.v.position, directionUnary[type - ROTATE_X]);
            }

            const float len = IntersectRayPlane(gContext.mRayOrigin, gContext.mRayVector, gContext.mTranslationPlan);
            vec_t localPos = gContext.mRayOrigin + gContext.mRayVector * len - gContext.mModel.v.position;
            gContext.mRotationVectorSource = Normalized(localPos);
            gContext.mRotationAngleOrigin = ComputeAngleOnPlan();
         }
      }

      // rotation
      if (gContext.mbUsing && (gContext.mActualID == -1 || gContext.mActualID == gContext.mEditingID))
      {
         ImGui::CaptureMouseFromApp();
         gContext.mRotationAngle = ComputeAngleOnPlan();
         if (snap)
         {
            float snapInRadian = snap[0] * DEG2RAD;
            ComputeSnap(&gContext.mRotationAngle, snapInRadian);
         }
         vec_t rotationAxisLocalSpace;

         rotationAxisLocalSpace.TransformVector(makeVect(gContext.mTranslationPlan.x, gContext.mTranslationPlan.y, gContext.mTranslationPlan.z, 0.f), gContext.mModelInverse);
         rotationAxisLocalSpace.Normalize();

         matrix_t deltaRotation;
         deltaRotation.RotationAxis(rotationAxisLocalSpace, gContext.mRotationAngle - gContext.mRotationAngleOrigin);
         if(gContext.mRotationAngle != gContext.mRotationAngleOrigin)
         {
             modified = true;
         }
         gContext.mRotationAngleOrigin = gContext.mRotationAngle;

         matrix_t scaleOrigin;
         scaleOrigin.Scale(gContext.mModelScaleOrigin);

         if (applyRotationLocaly)
         {
            *(matrix_t*)matrix = scaleOrigin * deltaRotation * gContext.mModel;
         }
         else
         {
            matrix_t res = gContext.mModelSource;
            res.v.position.Set(0.f);

            *(matrix_t*)matrix = res * deltaRotation;
            ((matrix_t*)matrix)->v.position = gContext.mModelSource.v.position;
         }

         if (deltaMatrix)
         {
            *(matrix_t*)deltaMatrix = gContext.mModelInverse * deltaRotation * gContext.mModel;
         }

         if (!io.MouseDown[0])
         {
            gContext.mbUsing = false;
            gContext.mEditingID = -1;
         }
         type = gContext.mCurrentOperation;
      }
      return modified;
   }

   void DecomposeMatrixToComponents(const float* matrix, float* translation, float* rotation, float* scale)
   {
      matrix_t mat = *(matrix_t*)matrix;

      scale[0] = mat.v.right.Length();
      scale[1] = mat.v.up.Length();
      scale[2] = mat.v.dir.Length();

      mat.OrthoNormalize();

      rotation[0] = RAD2DEG * atan2f(mat.m[1][2], mat.m[2][2]);
      rotation[1] = RAD2DEG * atan2f(-mat.m[0][2], sqrtf(mat.m[1][2] * mat.m[1][2] + mat.m[2][2] * mat.m[2][2]));
      rotation[2] = RAD2DEG * atan2f(mat.m[0][1], mat.m[0][0]);

      translation[0] = mat.v.position.x;
      translation[1] = mat.v.position.y;
      translation[2] = mat.v.position.z;
   }

   void RecomposeMatrixFromComponents(const float* translation, const float* rotation, const float* scale, float* matrix)
   {
      matrix_t& mat = *(matrix_t*)matrix;

      matrix_t rot[3];
      for (int i = 0; i < 3; i++)
      {
         rot[i].RotationAxis(directionUnary[i], rotation[i] * DEG2RAD);
      }

      mat = rot[0] * rot[1] * rot[2];

      float validScale[3];
      for (int i = 0; i < 3; i++)
      {
         if (fabsf(scale[i]) < FLT_EPSILON)
         {
            validScale[i] = 0.001f;
         }
         else
         {
            validScale[i] = scale[i];
         }
      }
      mat.v.right *= validScale[0];
      mat.v.up *= validScale[1];
      mat.v.dir *= validScale[2];
      mat.v.position.Set(translation[0], translation[1], translation[2], 1.f);
   }

   void SetID(int id)
   {
      gContext.mActualID = id;
   }

   bool Manipulate(const float* view, const float* projection, OPERATION operation, MODE mode, float* matrix, float* deltaMatrix, float* snap, float* localBounds, float* boundsSnap)
   {
      ComputeContext(view, projection, matrix, mode);

      // set delta to identity
      if (deltaMatrix)
      {
         ((matrix_t*)deltaMatrix)->SetToIdentity();
      }

      // behind camera
      vec_t camSpacePosition;
      camSpacePosition.TransformPoint(makeVect(0.f, 0.f, 0.f), gContext.mMVP);
      if (!gContext.mIsOrthographic && camSpacePosition.z < 0.001f)
      {
         return false;
      }

      // --
      int type = NONE;
      bool manipulated = false;
      if (gContext.mbEnable)
      {
         if (!gContext.mbUsingBounds)
         {
            switch (operation)
            {
            case ROTATE:
               manipulated = HandleRotation(matrix, deltaMatrix, type, snap);
               break;
            case TRANSLATE:
               manipulated = HandleTranslation(matrix, deltaMatrix, type, snap);
               break;
            case SCALE:
               manipulated = HandleScale(matrix, deltaMatrix, type, snap);
               break;
            case BOUNDS:
               break;
            }
         }
      }

      if (localBounds && !gContext.mbUsing)
      {
         HandleAndDrawLocalBounds(localBounds, (matrix_t*)matrix, boundsSnap, operation);
      }

      gContext.mOperation = operation;
      if (!gContext.mbUsingBounds)
      {
         switch (operation)
         {
         case ROTATE:
            DrawRotationGizmo(type);
            break;
         case TRANSLATE:
            DrawTranslationGizmo(type);
            break;
         case SCALE:
            DrawScaleGizmo(type);
            break;
         case BOUNDS:
            break;
         }
      }
      return manipulated;
   }

   void SetGizmoSizeClipSpace(float value)
   {
       gGizmoSizeClipSpace = value;
   }

   ///////////////////////////////////////////////////////////////////////////////////////////////////
   void ComputeFrustumPlanes(vec_t* frustum, const float* clip)
   {
      frustum[0].x = clip[3] - clip[0];
      frustum[0].y = clip[7] - clip[4];
      frustum[0].z = clip[11] - clip[8];
      frustum[0].w = clip[15] - clip[12];

      frustum[1].x = clip[3] + clip[0];
      frustum[1].y = clip[7] + clip[4];
      frustum[1].z = clip[11] + clip[8];
      frustum[1].w = clip[15] + clip[12];

      frustum[2].x = clip[3] + clip[1];
      frustum[2].y = clip[7] + clip[5];
      frustum[2].z = clip[11] + clip[9];
      frustum[2].w = clip[15] + clip[13];

      frustum[3].x = clip[3] - clip[1];
      frustum[3].y = clip[7] - clip[5];
      frustum[3].z = clip[11] - clip[9];
      frustum[3].w = clip[15] - clip[13];

      frustum[4].x = clip[3] - clip[2];
      frustum[4].y = clip[7] - clip[6];
      frustum[4].z = clip[11] - clip[10];
      frustum[4].w = clip[15] - clip[14];

      frustum[5].x = clip[3] + clip[2];
      frustum[5].y = clip[7] + clip[6];
      frustum[5].z = clip[11] + clip[10];
      frustum[5].w = clip[15] + clip[14];

      for (int i = 0; i < 6; i++)
      {
         frustum[i].Normalize();
      }
   }

   void DrawCubes(const float* view, const float* projection, const float* matrices, int matrixCount)
   {
      matrix_t viewInverse;
      viewInverse.Inverse(*(matrix_t*)view);
      
      struct CubeFace
      {
         float z;
         ImVec2 faceCoordsScreen[4];
         ImU32 color;
      };
      CubeFace* faces = (CubeFace*)_malloca(sizeof(CubeFace) * matrixCount * 6);

      if (!faces)
      {
         return;
      }

      vec_t frustum[6];
      matrix_t viewProjection = *(matrix_t*)view * *(matrix_t*)projection;
      ComputeFrustumPlanes(frustum, viewProjection.m16);

      int cubeFaceCount = 0;
      for (int cube = 0; cube < matrixCount; cube++)
      {
         const float* matrix = &matrices[cube * 16];

         const matrix_t& model = *(matrix_t*)matrix;
         matrix_t res = *(matrix_t*)matrix * *(matrix_t*)view * *(matrix_t*)projection;
         matrix_t modelView = *(matrix_t*)matrix * *(matrix_t*)view;

         for (int iFace = 0; iFace < 6; iFace++)
         {
            const int normalIndex = (iFace % 3);
            const int perpXIndex = (normalIndex + 1) % 3;
            const int perpYIndex = (normalIndex + 2) % 3;
            const float invert = (iFace > 2) ? -1.f : 1.f;

            const vec_t faceCoords[4] = { directionUnary[normalIndex] + directionUnary[perpXIndex] + directionUnary[perpYIndex],
               directionUnary[normalIndex] + directionUnary[perpXIndex] - directionUnary[perpYIndex],
               directionUnary[normalIndex] - directionUnary[perpXIndex] - directionUnary[perpYIndex],
               directionUnary[normalIndex] - directionUnary[perpXIndex] + directionUnary[perpYIndex],
            };

            // clipping
            /*
            bool skipFace = false;
            for (unsigned int iCoord = 0; iCoord < 4; iCoord++)
            {
               vec_t camSpacePosition;
               camSpacePosition.TransformPoint(faceCoords[iCoord] * 0.5f * invert, res);
               if (camSpacePosition.z < 0.001f)
               {
                  skipFace = true;
                  break;
               }
            }
            if (skipFace)
            {
               continue;
            }
            */
            vec_t centerPosition, centerPositionVP;
            centerPosition.TransformPoint(directionUnary[normalIndex] * 0.5f * invert, *(matrix_t*)matrix);
            centerPositionVP.TransformPoint(directionUnary[normalIndex] * 0.5f * invert, res);

            bool inFrustum = true;
            for (int iFrustum = 0; iFrustum < 6; iFrustum++)
            {
               float dist = DistanceToPlane(centerPosition, frustum[iFrustum]);
               if (dist < 0.f)
               {
                  inFrustum = false;
                  break;
               }
            }

            if (!inFrustum)
            {
               continue;
            }
            CubeFace& cubeFace = faces[cubeFaceCount];

            // 3D->2D
            //ImVec2 faceCoordsScreen[4];
            for (unsigned int iCoord = 0; iCoord < 4; iCoord++)
            {
               cubeFace.faceCoordsScreen[iCoord] = worldToPos(faceCoords[iCoord] * 0.5f * invert, res);
            }
            cubeFace.color = directionColor[normalIndex] | 0x808080;
            
            cubeFace.z = centerPositionVP.z / centerPositionVP.w;
            cubeFaceCount++;
         }
      }
      qsort(faces, cubeFaceCount, sizeof(CubeFace), [](void const* _a, void const* _b){
            CubeFace* a = (CubeFace*)_a;
            CubeFace* b = (CubeFace*)_b;
            if (a->z < b->z)
            {
               return 1;
            }
            return -1;
         });
      // draw face with lighter color
      for (int iFace = 0; iFace < cubeFaceCount; iFace++)
      {
         const CubeFace& cubeFace = faces[iFace];
         gContext.mDrawList->AddConvexPolyFilled(cubeFace.faceCoordsScreen, 4, cubeFace.color);
      }
   }

   void DrawGrid(const float* view, const float* projection, const float* matrix, const float gridSize)
   {
      matrix_t viewProjection = *(matrix_t*)view * *(matrix_t*)projection;
      vec_t frustum[6];
      ComputeFrustumPlanes(frustum, viewProjection.m16);
      matrix_t res = *(matrix_t*)matrix * viewProjection;
         
      for (float f = -gridSize; f <= gridSize; f += 1.f)
      {
         for (int dir = 0; dir < 2; dir++)
         {
            vec_t ptA = makeVect(dir ? -gridSize : f, 0.f, dir ? f : -gridSize);
            vec_t ptB = makeVect(dir ? gridSize : f, 0.f, dir ? f : gridSize);
            bool visible = true;
            for (int i = 0; i < 6; i++)
            {
               float dA = DistanceToPlane(ptA, frustum[i]);
               float dB = DistanceToPlane(ptB, frustum[i]);
               if (dA < 0.f && dB < 0.f)
               {
                  visible = false;
                  break;
               }
               if (dA > 0.f && dB > 0.f)
               {
                  continue;
               }
               if (dA < 0.f)
               {
                  float len = fabsf(dA - dB);
                  float t = fabsf(dA) / len;
                  ptA.Lerp(ptB, t);
               }
               if (dB < 0.f)
               {
                  float len = fabsf(dB - dA);
                  float t = fabsf(dB) / len;
                  ptB.Lerp(ptA, t);
               }
            }
            if (visible)
            {
               ImU32 col = 0xFF808080;
               col = (fmodf(fabsf(f), 10.f) < FLT_EPSILON) ? 0xFF909090 : col;
               col = (fabsf(f) < FLT_EPSILON) ? 0xFF404040 : col;

               float thickness = 1.f;
               thickness = (fmodf(fabsf(f), 10.f) < FLT_EPSILON) ? 1.5f : thickness;
               thickness = (fabsf(f) < FLT_EPSILON) ? 2.3f : thickness;

               gContext.mDrawList->AddLine(worldToPos(ptA, res), worldToPos(ptB, res), col, thickness);
            }
         }
      }
   }

   void ViewManipulate(float* view, float length, ImVec2 position, ImVec2 size, ImU32 backgroundColor)
   {
      static bool isDraging = false;
      static bool isClicking = false;
      static bool isInside = false;
      static vec_t interpolationUp;
      static vec_t interpolationDir;
      static int interpolationFrames = 0;
      const vec_t referenceUp = makeVect(0.f, 1.f, 0.f);

      matrix_t svgView, svgProjection;
      svgView = gContext.mViewMat;
      svgProjection = gContext.mProjectionMat;

      ImGuiIO& io = ImGui::GetIO();
      gContext.mDrawList->AddRectFilled(position, position + size, backgroundColor);
      matrix_t viewInverse;
      viewInverse.Inverse(*(matrix_t*)view);

      const vec_t camTarget = viewInverse.v.position - viewInverse.v.dir * length;

      // view/projection matrices
      const float distance = 3.f;
      matrix_t cubeProjection, cubeView;
      float fov = acosf(distance / (sqrtf(distance * distance + 3.f))) * RAD2DEG;
      Perspective(fov / sqrtf(2.f), size.x / size.y, 0.01f, 1000.f, cubeProjection.m16);

      vec_t dir = makeVect(viewInverse.m[2][0], viewInverse.m[2][1], viewInverse.m[2][2]);
      vec_t up = makeVect(viewInverse.m[1][0], viewInverse.m[1][1], viewInverse.m[1][2]);
      vec_t eye = dir * distance;
      vec_t zero = makeVect(0.f, 0.f);
      LookAt(&eye.x, &zero.x, &up.x, cubeView.m16);

      // set context
      gContext.mViewMat = cubeView;
      gContext.mProjectionMat = cubeProjection;
      ComputeCameraRay(gContext.mRayOrigin, gContext.mRayVector, position, size);

      const matrix_t res = cubeView * cubeProjection;

      // panels
      static const ImVec2 panelPosition[9] = { ImVec2(0.75f,0.75f), ImVec2(0.25f, 0.75f), ImVec2(0.f, 0.75f),
         ImVec2(0.75f, 0.25f), ImVec2(0.25f, 0.25f), ImVec2(0.f, 0.25f),
         ImVec2(0.75f, 0.f), ImVec2(0.25f, 0.f), ImVec2(0.f, 0.f) };

      static const ImVec2 panelSize[9] = { ImVec2(0.25f,0.25f), ImVec2(0.5f, 0.25f), ImVec2(0.25f, 0.25f),
         ImVec2(0.25f, 0.5f), ImVec2(0.5f, 0.5f), ImVec2(0.25f, 0.5f),
         ImVec2(0.25f, 0.25f), ImVec2(0.5f, 0.25f), ImVec2(0.25f, 0.25f) };

      // tag faces
      bool boxes[27]{};
      for (int iPass = 0; iPass < 2; iPass++)
      {
         for (int iFace = 0; iFace < 6; iFace++)
         {
            const int normalIndex = (iFace % 3);
            const int perpXIndex = (normalIndex + 1) % 3;
            const int perpYIndex = (normalIndex + 2) % 3;
            const float invert = (iFace > 2) ? -1.f : 1.f;
            const vec_t indexVectorX = directionUnary[perpXIndex] * invert;
            const vec_t indexVectorY = directionUnary[perpYIndex] * invert;
            const vec_t boxOrigin = directionUnary[normalIndex] * -invert - indexVectorX - indexVectorY;
            const vec_t faceCoords[4] = { directionUnary[normalIndex] + directionUnary[perpXIndex] + directionUnary[perpYIndex],
                                          directionUnary[normalIndex] + directionUnary[perpXIndex] - directionUnary[perpYIndex],
                                          directionUnary[normalIndex] - directionUnary[perpXIndex] - directionUnary[perpYIndex],
                                          directionUnary[normalIndex] - directionUnary[perpXIndex] + directionUnary[perpYIndex] };

            // plan local space
            const vec_t n = directionUnary[normalIndex] * invert;
            vec_t viewSpaceNormal = n;
            vec_t viewSpacePoint = n * 0.5f;
            viewSpaceNormal.TransformVector(cubeView);
            viewSpaceNormal.Normalize();
            viewSpacePoint.TransformPoint(cubeView);
            const vec_t viewSpaceFacePlan = BuildPlan(viewSpacePoint, viewSpaceNormal);

            // back face culling
            if (viewSpaceFacePlan.w > 0.f)
            {
               continue;
            }

            const vec_t facePlan = BuildPlan(n * 0.5f, n);

            const float len = IntersectRayPlane(gContext.mRayOrigin, gContext.mRayVector, facePlan);
            vec_t posOnPlan = gContext.mRayOrigin + gContext.mRayVector * len - (n * 0.5f);

            float localx = Dot(directionUnary[perpXIndex], posOnPlan) * invert + 0.5f;
            float localy = Dot(directionUnary[perpYIndex], posOnPlan) * invert + 0.5f;

            // panels
            const vec_t dx = directionUnary[perpXIndex];
            const vec_t dy = directionUnary[perpYIndex];
            const vec_t origin = directionUnary[normalIndex] - dx - dy;
            for (int iPanel = 0; iPanel < 9; iPanel++)
            {
               vec_t boxCoord = boxOrigin + indexVectorX * float(iPanel % 3) + indexVectorY * float(iPanel / 3) + makeVect(1.f, 1.f, 1.f);
               const ImVec2 p = panelPosition[iPanel] * 2.f;
               const ImVec2 s = panelSize[iPanel] * 2.f;
               ImVec2 faceCoordsScreen[4];
               vec_t panelPos[4] = { dx * p.x + dy * p.y,
                                     dx * p.x + dy * (p.y + s.y),
                                     dx * (p.x + s.x) + dy * (p.y + s.y),
                                     dx * (p.x + s.x) + dy * p.y };

               for (unsigned int iCoord = 0; iCoord < 4; iCoord++)
               {
                  faceCoordsScreen[iCoord] = worldToPos((panelPos[iCoord] + origin) * 0.5f * invert, res, position, size);
               }

               const ImVec2 panelCorners[2] = { panelPosition[iPanel], panelPosition[iPanel] + panelSize[iPanel] };
               bool insidePanel = localx > panelCorners[0].x&& localx < panelCorners[1].x && localy > panelCorners[0].y&& localy < panelCorners[1].y;
               int boxCoordInt = int(boxCoord.x * 9.f + boxCoord.y * 3.f + boxCoord.z);
               assert(boxCoordInt < 27);
               boxes[boxCoordInt] |= insidePanel && (!isDraging);

               // draw face with lighter color
               if (iPass)
               {
                  gContext.mDrawList->AddConvexPolyFilled(faceCoordsScreen, 4, (directionColor[normalIndex] | 0x80808080) | (isInside ? 0x080808 : 0));
                  if (boxes[boxCoordInt])
                  {
                     gContext.mDrawList->AddConvexPolyFilled(faceCoordsScreen, 4, 0x8060A0F0);

                     if (!io.MouseDown[0] && !isDraging && isClicking)
                     {
                        // apply new view direction
                        int cx = boxCoordInt / 9;
                        int cy = (boxCoordInt - cx * 9) / 3;
                        int cz = boxCoordInt % 3;
                        interpolationDir = makeVect(1.f - cx, 1.f - cy, 1.f - cz);
                        interpolationDir.Normalize();

                        if (fabsf(Dot(interpolationDir, referenceUp)) > 1.0f - 0.01f)
                        {
                           vec_t right = viewInverse.v.right;
                           if (fabsf(right.x) > fabsf(right.z))
                           {
                              right.z = 0.f;
                           }
                           else
                           {
                              right.x = 0.f;
                           }
                           right.Normalize();
                           interpolationUp = Cross(interpolationDir, right);
                           interpolationUp.Normalize();
                        }
                        else
                        {
                           interpolationUp = referenceUp;
                        }
                        interpolationFrames = 40;
                        isClicking = false;
                     }
                     if (io.MouseDown[0] && !isDraging)
                     {
                        isClicking = true;
                     }
                  }
               }
            }
         }
      }
      if (interpolationFrames)
      {
         interpolationFrames--;
         vec_t newDir = viewInverse.v.dir;
         newDir.Lerp(interpolationDir, 0.2f);
         newDir.Normalize();

         vec_t newUp = viewInverse.v.up;
         newUp.Lerp(interpolationUp, 0.3f);
         newUp.Normalize();
         newUp = interpolationUp;
         vec_t newEye = camTarget + newDir * length;
         LookAt(&newEye.x, &camTarget.x, &newUp.x, view);
      }
      isInside = ImRect(position, position + size).Contains(io.MousePos);

      // drag view
      if (!isDraging && io.MouseDown[0] && isInside && (fabsf(io.MouseDelta.x) > 0.f || fabsf(io.MouseDelta.y) > 0.f))
      {
         isDraging = true;
         isClicking = false;
      }
      else if (isDraging && !io.MouseDown[0])
      {
         isDraging = false;
      }

      if (isDraging)
      {
         matrix_t rx, ry, roll;

         rx.RotationAxis(referenceUp, -io.MouseDelta.x * 0.01f);
         ry.RotationAxis(viewInverse.v.right, -io.MouseDelta.y * 0.01f);

         roll = rx * ry;

         vec_t newDir = viewInverse.v.dir;
         newDir.TransformVector(roll);
         newDir.Normalize();

         // clamp
         vec_t planDir = Cross(viewInverse.v.right, referenceUp);
         planDir.y = 0.f;
         planDir.Normalize();
         float dt = Dot(planDir, newDir);
         if (dt < 0.0f)
         {
            newDir += planDir * dt;
            newDir.Normalize();
         }

         vec_t newEye = camTarget + newDir * length;
         LookAt(&newEye.x, &camTarget.x, &referenceUp.x, view);
      }

      // restore view/projection because it was used to compute ray
      ComputeContext(svgView.m16, svgProjection.m16, gContext.mModelSource.m16, gContext.mMode);
   }
};