{glColorMask(false,false,false,true);//disable messing with the rgb channels, just change the alphaglClear(GL_COLOR_BUFFER_BIT);//clear the color buffer (just the alpha channel)//glClearColor(FillColor.r / 255.f, FillColor.g / 255.f, FillColor.b / 255.f, FillColor.a / 255.f))...