I got interested in Blendadd Shader while watching Diablo 3 vfx boot camp video. I didn’t know how to make it in Amplify Shader, So i went around the Internet and find that i have to use pre-multiplied to make it.So I made and test on Unity, and I think it’s going well.
But I wonder if this is the right way to do it !
that is all there is to it - a blend mode
One OneMinusSrcAlpha
colloquially called BlendAdd due to Julian Loves D3 talk at GDC but it is pre-multiplied alpha blending
difference is
Source * SourceAlpha (alpha)
vs
Source *ONE (pre mult)
pre-multiplied (on black) as in you don’t want to darken color more with it’s own alpha… you already painted it into the texture as if you wanted to use ‘additive’
the visual just require tweaking RGB and alpha to behave how you want.
the other distinction it has against alpha_blend is independence between color and alpha - Color and Alpha must drop to 0 in order for it to vanish because the color is identical to ‘additive’ blending
Thanks for reply! It really helped me a lot 
