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Pica/Rasterizer: Clean up and fix backface culling.

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This commit is contained in:
Tony Wasserka 2015-02-18 13:14:49 +01:00
parent 365236fa4c
commit 638b370fb5
1 changed files with 27 additions and 11 deletions
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38
src/video_core/rasterizer.cpp
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@ -90,9 +90,14 @@ static int SignedArea (const Math::Vec2<Fix12P4>& vtx1,
return Math::Cross(vec1, vec2).z;
};
void ProcessTriangle(const VertexShader::OutputVertex& v0,
const VertexShader::OutputVertex& v1,
const VertexShader::OutputVertex& v2)
/**
* Helper function for ProcessTriangle with the "reversed" flag to allow for implementing
* culling via recursion.
*/
static void ProcessTriangleInternal(const VertexShader::OutputVertex& v0,
const VertexShader::OutputVertex& v1,
const VertexShader::OutputVertex& v2,
bool reversed = false)
{
// vertex positions in rasterizer coordinates
auto FloatToFix = [](float24 flt) {
@ -106,17 +111,22 @@ void ProcessTriangle(const VertexShader::OutputVertex& v0,
ScreenToRasterizerCoordinates(v1.screenpos),
ScreenToRasterizerCoordinates(v2.screenpos) };
if (registers.cull_mode == Regs::CullMode::KeepCounterClockWise) {
// Reverse vertex order and use the CW code path.
std::swap(vtxpos[1], vtxpos[2]);
}
if (registers.cull_mode == Regs::CullMode::KeepAll) {
// Make sure we always end up with a triangle wound counter-clockwise
if (!reversed && SignedArea(vtxpos[0].xy(), vtxpos[1].xy(), vtxpos[2].xy()) <= 0) {
ProcessTriangleInternal(v0, v2, v1, true);
return;
}
} else {
if (!reversed && registers.cull_mode == Regs::CullMode::KeepClockWise) {
// Reverse vertex order and use the CCW code path.
ProcessTriangleInternal(v0, v2, v1, true);
return;
}
if (registers.cull_mode != Regs::CullMode::KeepAll) {
// Cull away triangles which are wound counter-clockwise.
// Cull away triangles which are wound clockwise.
if (SignedArea(vtxpos[0].xy(), vtxpos[1].xy(), vtxpos[2].xy()) <= 0)
return;
} else {
// TODO: Consider A check for degenerate triangles ("SignedArea == 0")
}
// TODO: Proper scissor rect test!
@ -695,6 +705,12 @@ void ProcessTriangle(const VertexShader::OutputVertex& v0,
}
}
void ProcessTriangle(const VertexShader::OutputVertex& v0,
const VertexShader::OutputVertex& v1,
const VertexShader::OutputVertex& v2) {
ProcessTriangleInternal(v0, v1, v2);
}
} // namespace Rasterizer
} // namespace Pica