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softgpu: Don't draw pixels which lie on the right side of a triangle.

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Tony Wasserka 2013-07-12 17:06:39 +02:00 committed by neobrain
parent 4231264008
commit b0d3848dc7
2 changed files with 21 additions and 3 deletions
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22
GPU/Software/Rasterizer.cpp
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@ -144,6 +144,18 @@ static inline bool DepthTestPassed(int x, int y, u16 z)
}
}
bool IsRightSideOrFlatBottomLine(const Vec2<u10>& vertex, const Vec2<u10>& line1, const Vec2<u10>& line2)
{
if (line1.y == line2.y) {
// just check if vertex is above us => bottom line parallel to x-axis
return vertex.y < line1.y;
} else {
// check if vertex is on our left => right side
return vertex.x < line1.x + (line2.x - line1.x) * (vertex.y - line1.y) / (line2.y - line1.y);
}
}
// Draws triangle, vertices specified in counter-clockwise direction (TODO: Make sure this is actually enforced)
void DrawTriangle(const VertexData& v0, const VertexData& v1, const VertexData& v2)
{
int minX = std::min(std::min(v0.drawpos.x, v1.drawpos.x), v2.drawpos.x);
@ -156,12 +168,16 @@ void DrawTriangle(const VertexData& v0, const VertexData& v1, const VertexData&
minY = std::max(minY, gstate.getScissorY1());
maxY = std::min(maxY, gstate.getScissorY2());
int bias0 = IsRightSideOrFlatBottomLine(v0.drawpos.xy(), v1.drawpos.xy(), v2.drawpos.xy()) ? -1 : 0;
int bias1 = IsRightSideOrFlatBottomLine(v1.drawpos.xy(), v2.drawpos.xy(), v0.drawpos.xy()) ? -1 : 0;
int bias2 = IsRightSideOrFlatBottomLine(v2.drawpos.xy(), v0.drawpos.xy(), v1.drawpos.xy()) ? -1 : 0;
DrawingCoords p(minX, minY, 0);
for (p.y = minY; p.y <= maxY; ++p.y) {
for (p.x = minX; p.x <= maxX; ++p.x) {
int w0 = orient2d(v1.drawpos, v2.drawpos, p);
int w1 = orient2d(v2.drawpos, v0.drawpos, p);
int w2 = orient2d(v0.drawpos, v1.drawpos, p);
int w0 = orient2d(v1.drawpos, v2.drawpos, p) + bias0;
int w1 = orient2d(v2.drawpos, v0.drawpos, p) + bias1;
int w2 = orient2d(v0.drawpos, v1.drawpos, p) + bias2;
// If p is on or inside all edges, render pixel
// TODO: Should only render when it's on the left of the right edge

2
GPU/Software/TransformUnit.h
View File

@ -43,6 +43,8 @@ struct DrawingCoords
u10 x;
u10 y;
u16 z;
Vec2<u10> xy() const { return Vec2<u10>(x, y); }
};
struct VertexData