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updated formulas

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Orange
2026-04-23 19:48:55 +03:00
parent 42a8a5a763
commit b3ba9eaadf
3 changed files with 72 additions and 38 deletions
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29
source/engines/source_engine/formulas.cpp
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@@ -39,30 +39,23 @@ namespace omath::source_engine
const float far, const NDCDepthRange ndc_depth_range) noexcept
{
// Source (inherited from Quake) stores FOV as horizontal FOV at a 4:3
// reference aspect. Convert to vertical FOV first, then use the
// standard vfov-based projection against the caller's actual aspect.
// reference aspect. Convert to true vertical FOV, then delegate to the
// standard vertical-FOV left-handed builder with the caller's actual
// aspect ratio.
// vfov = 2 · atan( tan(hfov_4:3 / 2) / (4/3) )
constexpr float k_source_reference_aspect = 4.f / 3.f;
const float half_hfov_4_3 = angles::degrees_to_radians(field_of_view) / 2.f;
const float tan_half_vfov = std::tan(half_hfov_4_3) / k_source_reference_aspect;
const float x_axis = 1.f / (aspect_ratio * tan_half_vfov);
const float y_axis = 1.f / tan_half_vfov;
const float vfov_deg = angles::radians_to_degrees(
2.f * std::atan(std::tan(half_hfov_4_3) / k_source_reference_aspect));
if (ndc_depth_range == NDCDepthRange::ZERO_TO_ONE)
return {
{x_axis, 0, 0, 0},
{0, y_axis, 0, 0},
{0, 0, far / (far - near), -(near * far) / (far - near)},
{0, 0, 1, 0},
};
return mat_perspective_left_handed<
float, MatStoreType::ROW_MAJOR, NDCDepthRange::ZERO_TO_ONE>(
vfov_deg, aspect_ratio, near, far);
if (ndc_depth_range == NDCDepthRange::NEGATIVE_ONE_TO_ONE)
return {
{x_axis, 0, 0, 0},
{0, y_axis, 0, 0},
{0, 0, (far + near) / (far - near), -(2.f * far * near) / (far - near)},
{0, 0, 1, 0},
};
return mat_perspective_left_handed<
float, MatStoreType::ROW_MAJOR, NDCDepthRange::NEGATIVE_ONE_TO_ONE>(
vfov_deg, aspect_ratio, near, far);
std::unreachable();
}
} // namespace omath::source_engine