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Treat alpha as 0 if alpha is 1 for blending

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This removes the white box in fortune street again, without causing Mario Kart Wii to regress.
This commit is contained in:
Pokechu22 2022-01-24 22:48:43 -08:00
parent 0327e6acb4
commit 444f6fd0cb
3 changed files with 28 additions and 0 deletions
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13
Source/Core/VideoBackends/Software/Tev.cpp
View File

@ -714,6 +714,19 @@ void Tev::Draw()
if (!TevAlphaTest(output[ALP_C]))
return;
// Hardware testing indicates that an alpha of 1 can pass an alpha test,
// but doesn't do anything in blending
// This situation is important for Mario Kart Wii's menus (they will render incorrectly if the
// alpha test for the FMV in the background fails, since they depend on depth for drawing a yellow
// border) and Fortune Street's gameplay (where a rectangle with an alpha value of 1 is drawn over
// the center of the screen several times, but those rectangles shouldn't be visible).
// Blending seems to result in no changes to the output with an alpha of 1, even if the input
// color is white.
// TODO: Investigate this further: we might be handling blending incorrectly in general (though
// there might not be any good way of changing blending behavior)
if (output[ALP_C] == 1)
output[ALP_C] = 0;
// z texture
if (bpmem.ztex2.op != ZTexOp::Disabled)
{

12
Source/Core/VideoCommon/PixelShaderGen.cpp
View File

@ -1234,6 +1234,18 @@ ShaderCode GeneratePixelShaderCode(APIType api_type, const ShaderHostConfig& hos
use_dual_source || use_shader_blend);
}
// This situation is important for Mario Kart Wii's menus (they will render incorrectly if the
// alpha test for the FMV in the background fails, since they depend on depth for drawing a yellow
// border) and Fortune Street's gameplay (where a rectangle with an alpha value of 1 is drawn over
// the center of the screen several times, but those rectangles shouldn't be visible).
// Blending seems to result in no changes to the output with an alpha of 1, even if the input
// color is white.
// TODO: Investigate this further: we might be handling blending incorrectly in general (though
// there might not be any good way of changing blending behavior)
out.Write("\t// Hardware testing indicates that an alpha of 1 can pass an alpha test,\n"
"\t// but doesn't do anything in blending\n"
"\tif (prev.a == 1) prev.a = 0;\n");
if (uid_data->zfreeze)
{
out.SetConstantsUsed(C_ZSLOPE, C_ZSLOPE);

3
Source/Core/VideoCommon/UberShaderPixel.cpp
View File

@ -1032,6 +1032,9 @@ ShaderCode GenPixelShader(APIType api_type, const ShaderHostConfig& host_config,
" }}\n"
"\n");
out.Write(" // Hardware testing indicates that an alpha of 1 can pass an alpha test,\n"
" // but doesn't do anything in blending\n"
" if (TevResult.a == 1) TevResult.a = 0;\n");
// =========
// Dithering
// =========