gpu: sw: Copy polygon alpha into the alpha channel of the vertex color.

fleroviux · Jan 10, 2024 · d0130d0 · d0130d0
1 parent 48ed11a
commit d0130d0
Showing 1 changed file with 4 additions and 0 deletions.
diff --git a/src/dual/src/nds/video_unit/gpu/renderer/software/rasterizer.cpp b/src/dual/src/nds/video_unit/gpu/renderer/software/rasterizer.cpp
@@ -244,6 +244,8 @@ namespace dual::nds::gpu {
   void SoftwareRenderer::RenderPolygonSpan(const Polygon& polygon, const Line& line, i32 y, int x0, int x1) {
     const i32 depth_test_threshold = m_enable_w_buffer ? 0xFF : 0x200;
 
+    const u32 alpha = polygon.attributes.alpha << 1 | polygon.attributes.alpha >> 4;
+
     Interpolator<8> line_interp{};
     Color4 color;
     Vector2<Fixed12x4> uv;
@@ -279,6 +281,8 @@ namespace dual::nds::gpu {
       line_interp.Perp(line.color[0], line.color[1], color);
       line_interp.Perp(line.uv[0], line.uv[1], uv);
 
+      color.A() = (i8)alpha;
+
       if(m_io.disp3dcnt.enable_texture_mapping && polygon.texture_params.format != TextureParams::Format::Disabled) {
         const Color4 texel = SampleTexture(polygon.texture_params, polygon.palette_base, uv);