I want to add a blend mode equivalent to self.gl.blendFuncSeparate(self.gl.SRC_ALPHA, self.gl.ONE_MINUS_SRC_ALPHA, self.gl.ZERO, self.gl.ONE);
In OGLGraphics.cpp::SetBlendMode() and D3D11Graphics.cpp::PrepareDraw(), it can have custom alpha factor, which is fine.
But can D3D9 do this?
Read a bit M$ doc, still not certain.