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LibSoftGPU: Divide texture coordinates by Q

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Up until now, we have only dealt with games that pass Q = 1 for their
texture coordinates. PrBoom+, however, relies on proper homogenous
texture coordinates for its relatively complex sky rendering, which
means that we should perform this per-fragment division.
This commit is contained in:
Jelle Raaijmakers 2022-09-06 23:13:48 +02:00 • committed by Linus Groh
parent 72782d845d
commit 087f565700
1 changed files with 2 additions and 13 deletions
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15
Userland/Libraries/LibSoftGPU/Device.cpp
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@ -633,18 +633,6 @@ void Device::rasterize_point_antialiased(GPU::Vertex& point)
void Device::rasterize_point(GPU::Vertex& point)
{
// Divide texture coordinates R, S and T by Q
for (size_t i = 0; i < GPU::NUM_TEXTURE_UNITS; ++i) {
auto& tex_coord = point.tex_coords[i];
auto one_over_w = 1 / tex_coord.w();
tex_coord = {
tex_coord.x() * one_over_w,
tex_coord.y() * one_over_w,
tex_coord.z() * one_over_w,
tex_coord.w(),
};
}
if (m_options.point_smooth)
rasterize_point_antialiased(point);
else
@ -1188,7 +1176,8 @@ ALWAYS_INLINE void Device::shade_fragments(PixelQuad& quad)
continue;
auto const& sampler = m_samplers[i];
auto texel = sampler.sample_2d(quad.texture_coordinates[i].xy());
// OpenGL 2.0 ¶ 3.5.1 states (in a roundabout way) that texture coordinates must be divided by Q
auto texel = sampler.sample_2d(quad.texture_coordinates[i].xy() / quad.texture_coordinates[i].w());
texture_stage_texel[i] = texel;
INCREASE_STATISTICS_COUNTER(g_num_sampler_calls, 1);