Ok, I’ve gotten closer, but stuck again. Using cc.alphaglue.jxs, I can apply individual alphas to my videos, but when running that through 43j-fourwaymix.js, I get the combined individual alphas matting an additive mix of all the videos. I am trying to get each matte to stay with its individual video. I also tried daisy chaining slabs with co.alphablend.jxs (daisy chaining because co.alphablend.jxs only expects 2 inputs). But that was a mess. I’m not sure if this can be solved using the existing shaders or if I need to modify them – but I couldn’t quite figure out how to modify either of those to do this.
I’ve attached my latest patch. The rendering subpatcher starts with putting together what Hubert had done, then adds the alphaglues in the slabrenderer_mod subpatcher. Thanks much for any help!