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Rasterizer: Pre-divide vertex attributes by W

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Execute the division-by-W for perspective-correct interpolation of
values in the clipper, moving them out of the rasterization inner loop.
This commit is contained in:
Yuri Kunde Schlesner 2014-12-23 13:05:51 -02:00
parent fe186d3a59
commit 8369ee5803
3 changed files with 32 additions and 8 deletions
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7
src/video_core/rasterizer.cpp
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@ -106,10 +106,7 @@ void ProcessTriangle(const VertexShader::OutputVertex& v0,
int bias1 = IsRightSideOrFlatBottomEdge(vtxpos[1].xy(), vtxpos[2].xy(), vtxpos[0].xy()) ? -1 : 0;
int bias2 = IsRightSideOrFlatBottomEdge(vtxpos[2].xy(), vtxpos[0].xy(), vtxpos[1].xy()) ? -1 : 0;
const Math::Vec3<float24> w_inverse = Math::MakeVec(
float24::FromFloat32(1.0f) / v0.pos.w,
float24::FromFloat32(1.0f) / v1.pos.w,
float24::FromFloat32(1.0f) / v2.pos.w);
auto w_inverse = Math::MakeVec(v0.pos.w, v1.pos.w, v2.pos.w);
auto textures = registers.GetTextures();
auto tev_stages = registers.GetTevStages();
@ -158,7 +155,7 @@ void ProcessTriangle(const VertexShader::OutputVertex& v0,
//
// The generalization to three vertices is straightforward in baricentric coordinates.
auto GetInterpolatedAttribute = [&](float24 attr0, float24 attr1, float24 attr2) {
auto attr_over_w = Math::MakeVec(attr0, attr1, attr2) * w_inverse;
auto attr_over_w = Math::MakeVec(attr0, attr1, attr2);
float24 interpolated_attr_over_w = Math::Dot(attr_over_w, baricentric_coordinates);
return interpolated_attr_over_w * interpolated_w_inverse;
};