How to use blend modes in a render texture?

[AndrewJS]

If I render blend modes like add or multiply in a render texture, they render with black where the transparency would be if I render them against a background.

I don't think I can get the blend mode to affect background layers when rendering into a render texture, I'd probably have to put each layer with the same blend mode in a separate render texture and use the blend mode on the whole texture.

Is there a way to have the blend mode layers render transparent instead of black in the render texture though?

[ivan.popelyshev]

ADD is possible if you modify default shader ( maybe mesh shader) that way it outputs alpha=0 , then any normal-blend will work as add-blend in those parts of texture.

mesh shader: https://pixijs.io/examples/#/mesh-and-shaders/triangle-textured.js

how to batch in case you need many ADD particles: 

MULTIPLY - not possible, need to know what happens on background, extra input for shader, pixi-picture plugin that I still didnt port to v5