Using the depth texture of one WebGL context in another context

Questions
1

Hello,
I have two WebGL contexts running, one on top of another, with the top one being a transparent canvas. I’m trying to use a render target in the bottom context to render a depth texture so I can use the depth data in a post processing shader in the top context. I’m having some difficulty doing this. It seems that the depth texture is empty when I’m using it in the top context.

Any help will be appericiated!
Thanks

2

For start, is it even possible?

3

See Multiple renderer & texture.

I have never tried it, but maybe if you read back the texture (as an image), you can draw it in another texture, but this will come with a severe performance penalty.

4

Yeah, I thought about it, but it’s not a performance penalty I can tolerate.

I’m currently trying to refactor my code to use a single renderer and context, and switch canvases.