rasterizer: Implement AddSigned combiner function for alpha channel.

master
bunnei 2015-05-25 00:40:01 +07:00
parent 1574c44586
commit 3b5ff61201
1 changed files with 7 additions and 0 deletions

@ -570,6 +570,13 @@ static void ProcessTriangleInternal(const VertexShader::OutputVertex& v0,
case Operation::Add:
return std::min(255, input[0] + input[1]);
case Operation::AddSigned:
{
// TODO(bunnei): Verify that the color conversion from (float) 0.5f to (byte) 128 is correct
auto result = static_cast<int>(input[0]) + static_cast<int>(input[1]) - 128;
return static_cast<u8>(MathUtil::Clamp<int>(result, 0, 255));
}
case Operation::Lerp:
return (input[0] * input[2] + input[1] * (255 - input[2])) / 255;