diff options
Diffstat (limited to 'src/video_core/rasterizer.cpp')
| -rw-r--r-- | src/video_core/rasterizer.cpp | 69 |
1 files changed, 38 insertions, 31 deletions
diff --git a/src/video_core/rasterizer.cpp b/src/video_core/rasterizer.cpp index 4dfc21885..9850e517a 100644 --- a/src/video_core/rasterizer.cpp +++ b/src/video_core/rasterizer.cpp @@ -55,30 +55,45 @@ static void SetDepth(int x, int y, u16 value) { *(depth_buffer + x + y * registers.framebuffer.GetWidth()) = value; } -void ProcessTriangle(const VertexShader::OutputVertex& v0, - const VertexShader::OutputVertex& v1, - const VertexShader::OutputVertex& v2) -{ - // NOTE: Assuming that rasterizer coordinates are 12.4 fixed-point values - struct Fix12P4 { - Fix12P4() {} - Fix12P4(u16 val) : val(val) {} +// NOTE: Assuming that rasterizer coordinates are 12.4 fixed-point values +struct Fix12P4 { + Fix12P4() {} + Fix12P4(u16 val) : val(val) {} - static u16 FracMask() { return 0xF; } - static u16 IntMask() { return (u16)~0xF; } + static u16 FracMask() { return 0xF; } + static u16 IntMask() { return (u16)~0xF; } - operator u16() const { - return val; - } + operator u16() const { + return val; + } - bool operator < (const Fix12P4& oth) const { - return (u16)*this < (u16)oth; - } + bool operator < (const Fix12P4& oth) const { + return (u16)*this < (u16)oth; + } - private: - u16 val; - }; +private: + u16 val; +}; + +/** + * Calculate signed area of the triangle spanned by the three argument vertices. + * The sign denotes an orientation. + * + * @todo define orientation concretely. + */ +static int SignedArea (const Math::Vec2<Fix12P4>& vtx1, + const Math::Vec2<Fix12P4>& vtx2, + const Math::Vec2<Fix12P4>& vtx3) { + const auto vec1 = Math::MakeVec(vtx2 - vtx1, 0); + const auto vec2 = Math::MakeVec(vtx3 - vtx1, 0); + // TODO: There is a very small chance this will overflow for sizeof(int) == 4 + return Math::Cross(vec1, vec2).z; +}; +void ProcessTriangle(const VertexShader::OutputVertex& v0, + const VertexShader::OutputVertex& v1, + const VertexShader::OutputVertex& v2) +{ // vertex positions in rasterizer coordinates auto FloatToFix = [](float24 flt) { return Fix12P4(static_cast<unsigned short>(flt.ToFloat32() * 16.0f)); @@ -86,14 +101,6 @@ void ProcessTriangle(const VertexShader::OutputVertex& v0, auto ScreenToRasterizerCoordinates = [FloatToFix](const Math::Vec3<float24> vec) { return Math::Vec3<Fix12P4>{FloatToFix(vec.x), FloatToFix(vec.y), FloatToFix(vec.z)}; }; - static auto orient2d = [](const Math::Vec2<Fix12P4>& vtx1, - const Math::Vec2<Fix12P4>& vtx2, - const Math::Vec2<Fix12P4>& vtx3) { - const auto vec1 = Math::MakeVec(vtx2 - vtx1, 0); - const auto vec2 = Math::MakeVec(vtx3 - vtx1, 0); - // TODO: There is a very small chance this will overflow for sizeof(int) == 4 - return Math::Cross(vec1, vec2).z; - }; Math::Vec3<Fix12P4> vtxpos[3]{ ScreenToRasterizerCoordinates(v0.screenpos), ScreenToRasterizerCoordinates(v1.screenpos), @@ -107,7 +114,7 @@ void ProcessTriangle(const VertexShader::OutputVertex& v0, if (registers.cull_mode != Regs::CullMode::KeepAll) { // Cull away triangles which are wound clockwise. // TODO: A check for degenerate triangles ("== 0") should be considered for CullMode::KeepAll - if (orient2d(vtxpos[0].xy(), vtxpos[1].xy(), vtxpos[2].xy()) <= 0) + if (SignedArea(vtxpos[0].xy(), vtxpos[1].xy(), vtxpos[2].xy()) <= 0) return; } @@ -153,9 +160,9 @@ void ProcessTriangle(const VertexShader::OutputVertex& v0, for (u16 x = min_x; x < max_x; x += 0x10) { // Calculate the barycentric coordinates w0, w1 and w2 - int w0 = bias0 + orient2d(vtxpos[1].xy(), vtxpos[2].xy(), {x, y}); - int w1 = bias1 + orient2d(vtxpos[2].xy(), vtxpos[0].xy(), {x, y}); - int w2 = bias2 + orient2d(vtxpos[0].xy(), vtxpos[1].xy(), {x, y}); + int w0 = bias0 + SignedArea(vtxpos[1].xy(), vtxpos[2].xy(), {x, y}); + int w1 = bias1 + SignedArea(vtxpos[2].xy(), vtxpos[0].xy(), {x, y}); + int w2 = bias2 + SignedArea(vtxpos[0].xy(), vtxpos[1].xy(), {x, y}); int wsum = w0 + w1 + w2; // If current pixel is not covered by the current primitive |