We use premultiplied alpha in our render code, so you will need to multiply your r, g and b values by color.a in order to get the proper effect. You can see our standard code here:
For the meantime, ShaderFilter is disabled, but we hope to add hardware-based filters again when we can design a better system that runs faster than our previous approach
I have tried with the shader that you have posted but I can’t get it work. Do I have to configure something? When I apply the shader the bitmap disappear. I’m targeting to HTML.