perspectivecamera.cc

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#include <xcal/camera/perspectivecamera.hpp>
 
void xcal::camera::PerspectiveCamera::update_projection_matrix() const {
    if (!projection_should_update()) return;
 
    const float fov_rad = fov_.value() * xcmath::PI / 180.0f;
    const float tan_half = std::tan(fov_rad * 0.5f);
    const float n = near_.value();
    const float f = far_.value();
    const float a = aspect_.value();
 
    auto& P = projection_matrix_cache_;
    P = xcmath::mat<float_t, 4, 4>{0.0f};
 
    // 行主序
    P[0][0] = 1.0f / (a * tan_half);
    P[1][1] = 1.0f / tan_half;
    P[2][2] = -(f + n) / (f - n);
    P[2][3] = -2.0f * f * n / (f - n);
    P[3][2] = -1.0f;
    // 其余元素保持 0
 
    fov_.reset_changed();
    aspect_.reset_changed();
    near_.reset_changed();
    far_.reset_changed();
    projection_has_changed();
}
xcal::bool_t xcal::camera::PerspectiveCamera::projection_should_update() const {
    return fov_.is_changed() || aspect_.is_changed() || near_.is_changed() ||
           far_.is_changed();
};
const xcmath::mat<float_t, 4, 4>&
xcal::camera::PerspectiveCamera::projection_matrix() const {
    update_projection_matrix();
    return projection_matrix_cache_;
}