It's not described in the documentation, but dual-source blending in DirectX 11
D3D11_BLEND_SRC1_COLOR is achieved using SV_TARGET1.
You would have a BlendState like this (all in fx format):
BlendState CompositeBlend
{
BlendEnable[0] =TRUE;
SrcBlend =ONE;
DestBlend =SRC1_COLOR;
BlendOp =ADD;
};
And an output structure that looks like it's writing to two rendertargets. But you only have one rendertarget!
struct TwoColourOutput
{
float4 add :SV_TARGET0;
float4 multiply :SV_TARGET1;
};
And then the pixel shader does:
TwoColourOutput PSMain(v2f IN) : SV_TARGET
{
TwoColourOutput result =...
return result;
}
The result - the value in the rendertarget is multiplied by result.multiply, and then result.add is added to it. Viola!
