For now
case OVERLAY:
gl.blendEquation (gl.FUNC_ADD);
gl.blendFunc (gl.DST_COLOR, gl.SRC_COLOR);
but I might need others in the future. It doesn’t seem to be exact overlay blend in mathematical sense, but looks close enough and works better for what I need it for anyway.
I found a nice cheatsheet about GL blends:
<img src=’/uploads/default/original/2X/e/eb8ec4f2cd656c389535f932998195db9b9563af.jpg’ width=“600” ">
and also GLSL implementations, if it could be done using shaders and we want exact Photoshop / Flash equivalents:
But as I said, even if we had exact overlay using GLSL, I’d still prefer to use stated GL blend equation. The idea was to replace renderSession.blendModeManager with my modified one, but I don’t know if it is possible to access renderSession which renders the stage from application code (also GLRenderContext which is needed by constructor).