Three.js: Shared context issue in 118+

[andrewstart]

Description of the problem

In version 118+, Three.js stops rendering when it shares a WebGL context with Pixi.js. In versions 117.1 and below, it works correctly.
Specifically, doing

threeRenderer.state.reset();
threeRenderer.render(myScene, myCamera);
pixiRenderer.reset();

is enough to cause the three.js renderer to not render anything on subsequent render attempts (although it clears the canvas correctly).

Codepen: https://codepen.io/andrewstart/pen/XWdybMw?editors=0010 (in settings, change the version of three.js to 117.1 to see a 3D ball correctly rendering behind the bunnies). This example doesn't seem to log any warnings, but in my actual project rendering a SphereBufferGeometry results in GL_INVALID_OPERATION: No element array buffer and no pointer.

Three.js version

• First appears in 118.0, still present in 120.1.

Browser

• [x] All of them - Tested in Chrome/Firefox, at least

[Mugen87]

Since r118 three.js uses a WebGL 2 rendering context by default. I could imagine that this breaks your usage pattern. You should be able to avoid a breakage by using WebGL1Renderer.

BTW: From my point of view, it is not recommended to share a WebGL context across different engines. three.js caches WebGL state information. If a cached information is changed by a different renderer, the final behavior is undefined.

[andrewstart]

Yes, it appears that while Pixi also uses WebGL2 by default, it doesn't correctly handle being given a WebGL 2 context and assumes that it is WebGL 1. I will dig on that a bit.
In regards to cached state information, doesn't threeRenderer.state.reset(); specifically clear that cached state (at the cost of some performance)?

[Mugen87]

In regards to cached state information, doesn't threeRenderer.state.reset(); specifically clear that cached state (at the cost of some performance)?

Yes, that's true. Although it's a bit unfortunate that this method is public accessible....

[yandeu]

Hi @andrewstart,

Did you find out how to mix three.js with pixi.js in >= r118

[andrewstart]

Nope, sticking with 117.1

[yandeu]

I have updated to r121 and do now use 2 canvas instead of sharing one. Works even better than before. _I'm using Phaser, not Pixi._