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62 lines
2.6 KiB
C++
62 lines
2.6 KiB
C++
//
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// Created by Vlad on 3/19/2025.
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//
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#include <omath/engines/source_engine/formulas.hpp>
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namespace omath::source_engine
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{
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Vector3<float> forward_vector(const ViewAngles& angles) noexcept
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{
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const auto vec = rotation_matrix(angles) * mat_column_from_vector(k_abs_forward);
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return {vec.at(0, 0), vec.at(1, 0), vec.at(2, 0)};
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}
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Mat4X4 rotation_matrix(const ViewAngles& angles) noexcept
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{
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return mat_rotation_axis_z(angles.yaw) * mat_rotation_axis_y(angles.pitch) * mat_rotation_axis_x(angles.roll);
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}
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Vector3<float> right_vector(const ViewAngles& angles) noexcept
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{
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const auto vec = rotation_matrix(angles) * mat_column_from_vector(k_abs_right);
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return {vec.at(0, 0), vec.at(1, 0), vec.at(2, 0)};
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}
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Vector3<float> up_vector(const ViewAngles& angles) noexcept
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{
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const auto vec = rotation_matrix(angles) * mat_column_from_vector(k_abs_up);
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return {vec.at(0, 0), vec.at(1, 0), vec.at(2, 0)};
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}
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Mat4X4 calc_view_matrix(const ViewAngles& angles, const Vector3<float>& cam_origin) noexcept
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{
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return mat_camera_view(forward_vector(angles), right_vector(angles), up_vector(angles), cam_origin);
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}
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Mat4X4 calc_perspective_projection_matrix(const float field_of_view, const float aspect_ratio, const float near,
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const float far, const NDCDepthRange ndc_depth_range) noexcept
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{
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// Source (inherited from Quake) stores FOV as horizontal FOV at a 4:3
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// reference aspect. Convert to true vertical FOV, then delegate to the
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// standard vertical-FOV left-handed builder with the caller's actual
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// aspect ratio.
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// vfov = 2 · atan( tan(hfov_4:3 / 2) / (4/3) )
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constexpr float k_source_reference_aspect = 4.f / 3.f;
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const float half_hfov_4_3 = angles::degrees_to_radians(field_of_view) / 2.f;
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const float vfov_deg = angles::radians_to_degrees(
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2.f * std::atan(std::tan(half_hfov_4_3) / k_source_reference_aspect));
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if (ndc_depth_range == NDCDepthRange::ZERO_TO_ONE)
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return mat_perspective_left_handed<
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float, MatStoreType::ROW_MAJOR, NDCDepthRange::ZERO_TO_ONE>(
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vfov_deg, aspect_ratio, near, far);
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if (ndc_depth_range == NDCDepthRange::NEGATIVE_ONE_TO_ONE)
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return mat_perspective_left_handed<
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float, MatStoreType::ROW_MAJOR, NDCDepthRange::NEGATIVE_ONE_TO_ONE>(
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vfov_deg, aspect_ratio, near, far);
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std::unreachable();
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}
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} // namespace omath::source_engine
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