refactor: separate graphics and application code

.clang-format

@@ -1,9 +1,9 @@
 ---
 Language: Cpp
 BasedOnStyle: LLVM
-AlignAfterOpenBracket: BlockIndent
+AlignAfterOpenBracket: AlwaysBreak
 AlignOperands:   AlignAfterOperator
-AlignArrayOfStructures: Right
+AlignArrayOfStructures: None
 AlignConsecutiveAssignments:
     Enabled:         true
     AlignCompound:   true
@@ -49,18 +49,25 @@ BraceWrapping:
     AfterUnion:      true
     BeforeCatch:     false
     BeforeElse:      false
+    IndentBraces: false
+    SplitEmptyFunction: false
+    SplitEmptyRecord: false
+    SplitEmptyNamespace: false
+BracedInitializerIndentWidth: 2
 BinPackParameters: OnePerLine
+BinPackLongBracedList: false
 BitFieldColonSpacing: Both
 BreakBeforeBinaryOperators: All
 BreakConstructorInitializers: BeforeComma
+# BreakAfterOpenBracketBracedList: true
 BreakInheritanceList: BeforeComma
 BreakStringLiterals: true
 ConstructorInitializerIndentWidth: 2
 ContinuationIndentWidth: 2
 ColumnLimit:     100
 EmptyLineAfterAccessModifier: Leave
 EmptyLineBeforeAccessModifier: Always
-FixNamespaceComments: true
+FixNamespaceComments: false
 JavaScriptQuotes: Single
 KeepEmptyLines:
     AtEndOfFile: true
@@ -100,5 +107,6 @@ SpaceBeforeParensOptions:
     AfterRequiresInExpression: true
 SpaceBeforeRangeBasedForLoopColon: true
 UseTab: Never
+Cpp11BracedListStyle: false
 ...
 

.gitignore

@@ -2,6 +2,7 @@
 .vs/
 .idea/
 .cache/
+ignore/
 
 # CMake
 CMakeSettings.json

CMakeLists.txt

@@ -2,58 +2,78 @@ cmake_minimum_required (VERSION 3.25)
 
 project (game VERSION 0.0.1 LANGUAGES CXX)
 
-set (CORE core)
-set (ENGINE engine)
-set (GAME ${PROJECT_NAME})
-
 option (BUILD_TESTS "Build tests" OFF)
 option (ENABLE_LINTER "Run fast static analysis (clang-tidy) during builds" OFF)
 option (ENABLE_DEEP_ANALYSIS "Run slow, deep static analysis (-fanalyzer or /analyze)" OFF)
 
 include (FetchContent)
 
+FetchContent_Declare (
+  SDL3
+  GIT_REPOSITORY      https://github.com/libsdl-org/SDL.git
+  GIT_TAG             release-3.4.10
+  GIT_SHALLOW         TRUE
+  FIND_PACKAGE_ARGS   3.4.0
+)
+set (DSDL_SHARED ON)
+set (DSDL_STATIC OFF)
+set (DSDL_TEST_LIBRARY OFF)
+FetchContent_MakeAvailable (SDL3)
+
+FetchContent_Declare (
+  glm
+  GIT_REPOSITORY      https://github.com/g-truc/glm.git
+  GIT_TAG             1.0.3
+  GIT_SHALLOW         TRUE
+  FIND_PACKAGE_ARGS   1.0.0
+)
+FetchContent_MakeAvailable (glm)
+
 if (BUILD_TESTS)
-    enable_testing ()
-    FetchContent_Declare (
-        Catch2
-        GIT_REPOSITORY      https://github.com/catchorg/Catch2.git
-        GIT_TAG             v3.15.0
-        GIT_SHALLOW         TRUE
-        FIND_PACKAGE_ARGS   3.0.0
-    )
-    FetchContent_MakeAvailable (Catch2)
+  enable_testing ()
+  FetchContent_Declare (
+    Catch2
+    GIT_REPOSITORY      https://github.com/catchorg/Catch2.git
+    GIT_TAG             v3.15.0
+    GIT_SHALLOW         TRUE
+    FIND_PACKAGE_ARGS   3.0.0
+  )
+  FetchContent_MakeAvailable (Catch2)
 endif ()
 
 add_subdirectory (core)
-add_subdirectory (engine)
+add_subdirectory (app)
+add_subdirectory (gfx)
 add_subdirectory (game)
 
 add_library(project_warnings INTERFACE)
 
 if (MSVC)
-    target_compile_options(project_warnings INTERFACE /W4)
+  target_compile_options(project_warnings INTERFACE /W4)
 else ()
-    target_compile_options(project_warnings INTERFACE -Wall -Wextra -Wpedantic)
+  target_compile_options(project_warnings INTERFACE -Wall -Wextra -Wpedantic)
 endif()
 
 if (ENABLE_DEEP_ANALYSIS)
-    if (MSVC)
-        target_compile_options (project_warnings INTERFACE /analyze)
-    elseif (CMAKE_CXX_COMPILER_ID STREQUAL "GNU")
-        target_compile_options (project_warnings INTERFACE -fanalyzer)
-    else ()
-        message (FATAL_ERROR "ENABLE_DEEP_ANALYSIS is ON, but ${CMAKE_CXX_COMPILER_ID} doesn't have an analyzer.")
-    endif ()
+  if (MSVC)
+    target_compile_options (project_warnings INTERFACE /analyze)
+  elseif (CMAKE_CXX_COMPILER_ID STREQUAL "GNU")
+    target_compile_options (project_warnings INTERFACE -fanalyzer)
+  else ()
+    message (FATAL_ERROR "ENABLE_DEEP_ANALYSIS is ON, but ${CMAKE_CXX_COMPILER_ID} doesn't have an analyzer.")
+  endif ()
 endif ()
 
-target_link_libraries(${CORE}   PRIVATE project_warnings)
-target_link_libraries(${ENGINE} PRIVATE project_warnings)
-target_link_libraries(${GAME}   PRIVATE project_warnings)
+target_link_libraries (core PRIVATE project_warnings)
+target_link_libraries (app  PRIVATE project_warnings)
+target_link_libraries (gfx  PRIVATE project_warnings)
+target_link_libraries (game PRIVATE project_warnings)
 
 if (ENABLE_LINTER)
-    find_program(CLANG_TIDY_EXE NAMES clang-tidy REQUIRED)
-    set_target_properties (${CORE}   PROPERTIES CXX_CLANG_TIDY "${CLANG_TIDY_EXE}")
-    set_target_properties (${ENGINE} PROPERTIES CXX_CLANG_TIDY "${CLANG_TIDY_EXE}")
-    set_target_properties (${GAME}   PROPERTIES CXX_CLANG_TIDY "${CLANG_TIDY_EXE}")
+  find_program(CLANG_TIDY_EXE NAMES clang-tidy REQUIRED)
+  set_target_properties (core PROPERTIES CXX_CLANG_TIDY "${CLANG_TIDY_EXE}")
+  set_target_properties (app  PROPERTIES CXX_CLANG_TIDY "${CLANG_TIDY_EXE}")
+  set_target_properties (gfx  PROPERTIES CXX_CLANG_TIDY "${CLANG_TIDY_EXE}")
+  set_target_properties (game PROPERTIES CXX_CLANG_TIDY "${CLANG_TIDY_EXE}")
 endif ()
 

app/CMakeLists.txt

@@ -0,0 +1,17 @@
+add_library (app)
+
+target_include_directories (
+  app
+  PUBLIC ${SDL3_INCLUDE_DIRS}
+  PUBLIC ${CMAKE_CURRENT_SOURCE_DIR}/include
+)
+
+target_link_libraries (
+  app
+  PUBLIC SDL3::SDL3
+  PUBLIC glm::glm
+  PUBLIC core
+)
+
+add_subdirectory (src)
+

engine/include/engine/input/cue.hh → app/include/app/cue.hh

@@ -2,22 +2,25 @@
 #include "core/bitmask.hh"
 #include "core/types.hh"
 #include <SDL3/SDL_scancode.h>
-// It's not clear that this is necessary
+
 struct Keyboard;
 struct Mouse;
+
 // Button state
 enum class On : u8 {
   Press   = 1 << 0,
   Release = 1 << 1,
   Repeat  = 1 << 2,
 };
+
 // Keyboard input modifiers
 enum class With : u8 {
   None  = 0,
   Ctrl  = 1 << 0,
   Shift = 1 << 1,
   Alt   = 1 << 2,
 };
+
 DEFINE_ENUM_BITWISE_OPERATORS(On)
 DEFINE_ENUM_BITWISE_OPERATORS(With)
 

engine/include/engine/event.hh → app/include/app/event.hh

@@ -1,4 +1,5 @@
 #pragma once
 #include <SDL3/SDL_events.h>
+
 bool      push_event(SDL_Event event);
 SDL_Event make_quit_event();

engine/include/engine/app.hh → app/include/app/main.hh

@@ -2,15 +2,13 @@
 
 // These functions need to be defined by an external binary linking against the engine.
 
-#include "engine/render/window.hh"
-#include "engine/time.hh"
+#include "app/time.hh"
 
 union SDL_Event;
 
 struct AppConfig
 {
-  Hertz        step_rate = 32u;
-  WindowConfig window;
+  Hertz step_rate = 32u;
 };
 
 // An opaque type defined by the application; the engine only holds and passes a pointer to it.
@@ -23,17 +21,17 @@ struct AppState;
 // Create `AppState` here. Returning null indicates application failure and `app_quit` will follow.
 [[nodiscard]] AppState* start();
 
-// Called 0 or more times per frame, once per elapsed timestep. Update  simulation systems and
+// Called 0 or more times per frame, once per elapsed timestep. Update simulation systems and
 // anything that needs determinism here. Time that can't be processed in this frame will be deferred
 // to the next frame, accumulating lag.
 void step(AppState& state);
 
 // Called once per frame. Advances by the time elapsed since the last frame, capped by 4 hertz.
 // Update user-interface, graphics, animations, and anything that doesn't need determinism here.
-void update(AppState& state, Nanoseconds dt);
+void update(AppState& state, f32 delta);
 
 // Called once per frame after `app_update` and `app_step`.
-void render(AppState& state);
+void render(AppState& state, f32 alpha);
 
 void handle_event(AppState& state, SDL_Event const& event);
 

engine/include/engine/time.hh → app/include/app/time.hh

@@ -1,22 +1,24 @@
 #pragma once
+
+// TODO: adopt std::chrono over SDL time
+
 #include "core/types.hh"
 
 using Hertz       = u64;
 using Nanoseconds = u64;
-using Seconds     = u64;
 
 // hertz to nanoseconds
 [[nodiscard]] constexpr Nanoseconds from_hertz(Hertz time) noexcept { return 1'000'000'000 / time; }
 
 // nanoseconds to seconds
-[[nodiscard]] constexpr Seconds to_seconds(Nanoseconds time) noexcept
+[[nodiscard]] constexpr f32 to_seconds(Nanoseconds time) noexcept
 {
-  return time / 1'000'000'000;
+  return f32(time) / 1'000'000'000.f;
 }
 
 struct TimeStep
 {
-  constexpr explicit TimeStep(u64 size) noexcept : size_{size}, lag_{0u}, age_{0u}
+  constexpr explicit TimeStep(u64 size) noexcept : size_{ size }, lag_{ 0u }, age_{ 0u }
   {
     // allow a step size of 0?
   }
@@ -27,7 +29,7 @@ struct TimeStep
     if (size_ == 0u) return 0u;
     lag_      += dt;
     u64 steps  = lag_ / size_;
-    lag_      -= size_ * steps;
+    lag_      -= steps * size_;
     age_      += steps;
     return steps;
   }
@@ -36,9 +38,11 @@ struct TimeStep
 
   [[nodiscard]] u64 age() const noexcept { return age_; }
 
+  [[nodiscard]] f32 alpha() const noexcept { return f32(lag_) / f32(size_); }
+
   [[nodiscard]] constexpr u64 size() const noexcept { return size_; }
 
-  void reset(u64 size)
+  void resize(u64 size)
   {
     size_ = size;
     lag_  = 0.f;

app/include/app/window.hh

@@ -0,0 +1,38 @@
+#pragma once
+#include "core/error.hh"
+#include "core/types.hh"
+#include <glm/ext/vector_int2.hpp>
+
+struct Window;
+
+struct SDL_Window;
+
+[[nodiscard]] Result<Window> create_window(std::string_view title, i32 width, i32 height);
+
+struct Window
+{
+  Window() noexcept                = default;
+  Window(Window const&)            = delete;
+  Window& operator=(Window const&) = delete;
+
+  explicit Window(SDL_Window*) noexcept;
+  Window(Window&&) noexcept;
+  Window& operator=(Window&&) noexcept;
+  ~Window() noexcept;
+
+  std::string_view title() const;
+
+  void set_title(std::string_view title);
+
+  [[nodiscard]] glm::ivec2 size() const noexcept;
+
+  void resize(i32 width, i32 height) noexcept;
+
+  [[nodiscard]] bool valid() const noexcept { return handle_ != nullptr; }
+
+  [[nodiscard]] SDL_Window* handle() noexcept { return handle_; }
+
+private:
+  SDL_Window* handle_ = nullptr;
+};
+

app/src/CMakeLists.txt

@@ -0,0 +1 @@
+target_sources (app PRIVATE main.cc event.cc keyboard.cc mouse.cc cue.cc window.cc)

engine/src/input/cue.cc → app/src/cue.cc

@@ -1,6 +1,6 @@
-#include "engine/input/cue.hh"
-#include "engine/input/keyboard.hh"
-#include "engine/input/mouse.hh"
+#include "app/cue.hh"
+#include "app/keyboard.hh"
+#include "app/mouse.hh"
 
 static bool keyboard_matches_modifier(Keyboard const& kb, With with)
 {

engine/src/event.cc → app/src/event.cc

@@ -1,4 +1,4 @@
-#include "engine/event.hh"
+#include "app/event.hh"
 #include <SDL3/SDL_log.h>
 #include <SDL3/SDL_timer.h>
 

engine/src/input/keyboard.cc → app/src/keyboard.cc

@@ -1,4 +1,4 @@
-#include "engine/input/keyboard.hh"
+#include "app/keyboard.hh"
 
 bool Keyboard::operator[](SDL_Scancode key) const { return state_.test(key); }