Issue with Firefox 64 and WebGL

[crazyquark]

Using the latest Firefox 64(or Firefox Developer edition) you get this warning all the time:
Error: WebGL warning: clear: This operation requires zeroing texture data. This is slow.
You can reproduce this in a lot of the three.js official examples like:
https://threejs.org/examples/#webgl_animation_cloth for example.

There is a reference in the Gecko code about this here:
https://github.com/mozilla/gecko-dev/blob/1cdb198bd9e1d2605ac48d2588e29475fb01a74e/dom/canvas/WebGLTexture.cpp#L636-L647

[Mugen87]

Yes, I can reproduce the warning with FF 64.0 and Mac OS 10.14.1. I think it makes sense to create a small fiddle that produces such a warning in order to better understand why this happens.

[crazyquark]

OK, I will try to edit it.

[Mugen87]

Wait, I already have a fiddle^^:

https://jsfiddle.net/f2Lommf5/16472/

Looks like it happens as soon as a shadow map is rendered. Can you confirm that the warning is logged on your machine? It should also disappear if you disable shadow maps.

[crazyquark]

Yes, I have deduced the same thing:
https://jsfiddle.net/f2Lommf5/16480/

Adding a light and enabling shadowMap on the renderer triggers it.

[crazyquark]

Yes, I can see the warning on your fiddle as well.
Disabling the shadowMap removes the warning.

[Mugen87]

I've debugged the issue and I think the problem is right here:

three.js/src/renderers/webgl/WebGLShadowMap.js

Lines 225 to 226 in 3013895

	_renderer.setRenderTarget( shadowMap );
	_renderer.clear();

The shadow map's render target is cleared right after its creation. You can simulate the same with the following fiddle:

https://jsfiddle.net/f2Lommf5/16484/

No problem in Chrome but FF logs the respective warning.

[Mugen87]

According to other posts, we might just ignore the warning:

pixijs/pixijs#4496 (comment)

http://www.html5gamedevs.com/topic/39057-this-operation-requires-zeroing-texture-data-this-is-slow/?tab=comments#comment-223038

[RemusMar]

You won't get this warning in the upcoming Firefox 65.

[Mugen87]

Indeed, with Firefox Beta (65.0b4) I'm not able to reproduce the warning on macOS.