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Revert improved culling frustum in OpenVR. #2375

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Merged
JulianGro merged 1 commit into from
Jul 24, 2026
+10 −59
Merged

Revert improved culling frustum in OpenVR. #2375

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69 changes: 10 additions & 59 deletions plugins/openvr/src/OpenVrDisplayPlugin.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -362,67 +362,17 @@ glm::mat4 OpenVrDisplayPlugin::getEyeProjection(Eye eye, const glm::mat4& basePr
}
}

inline static glm::mat4 fovToCullingProjection(const std::array<float, 4> fov, const float _near, const float _far) {
const float left = fov[0];
const float right = fov[1];
const float down = fov[2];
const float up = fov[3];

const float width = right - left;
const float height = up - down;

const float m11 = 2 / width;
const float m22 = 2 / height;
const float m33 = -(_far + _near) / (_far - _near);

const float m31 = (right + left) / width;
const float m32 = (up + down) / height;
const float m43 = -(_far * (_near + _near)) / (_far - _near);

// clang-format off
const float mat[16] = {
m11, 0 , 0 , 0,
0 , m22, 0 , 0,
m31, m32, m33, -1,
0 , 0 , m43, 0,
};
// clang-format on

return glm::make_mat4(mat);
}

glm::mat4 OpenVrDisplayPlugin::getCullingProjection(const glm::mat4& baseProjection) const {
if (!_system) {
if (_system) {
ViewFrustum baseFrustum;
baseFrustum.setProjection(baseProjection);
float baseNearClip = baseFrustum.getNearClip();
float baseFarClip = baseFrustum.getFarClip();
// FIXME Calculate the proper combined projection by using GetProjectionRaw values from both eyes
return toGlm(_system->GetProjectionMatrix((vr::EVREye)0, baseNearClip, baseFarClip));
} else {
return baseProjection;
}

std::array<std::array<float, 4>, 2> fovs;

for (auto i = 0; i < 2; i++) {
_system->GetProjectionRaw(
(vr::EVREye)i,
&fovs[i][0],
&fovs[i][1],
&fovs[i][2],
&fovs[i][3]
);
}

// FIXME: OpenVR gives us tan(angle), how can we clamp
// this to within ~170° when multiplied by margin?
// const float maxAngle = 0.9f * PI;
const float margin = 1.0f;

std::array<float, 4> fovMax = {
std::min(fovs[0][0], fovs[1][0]) * margin, // left
std::max(fovs[0][1], fovs[1][1]) * margin, // right
std::min(fovs[0][2], fovs[1][2]) * margin, // bottom (flipped)
std::max(fovs[0][3], fovs[1][3]) * margin, // top (flipped)
};

ViewFrustum frustum;
frustum.setProjection(baseProjection);
return fovToCullingProjection(fovMax, frustum.getNearClip(), frustum.getFarClip());
}

float OpenVrDisplayPlugin::getTargetFrameRate() const {
Expand Down Expand Up @@ -510,7 +460,8 @@ bool OpenVrDisplayPlugin::internalActivate() {
_eyeOffsets[eye] = toGlm(_system->GetEyeToHeadTransform(eye));
_eyeProjections[eye] = toGlm(_system->GetProjectionMatrix(eye, DEFAULT_NEAR_CLIP, DEFAULT_FAR_CLIP));
});
_cullingProjection = getCullingProjection(_eyeProjections[0]);
// FIXME Calculate the proper combined projection by using GetProjectionRaw values from both eyes
_cullingProjection = _eyeProjections[0];
});

// enable async time warp
Expand Down
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