GPUParticles2D not emitted in web export

[Sammy-T]

Godot version

4.0.1.stable

System information

Windows 10, NVIDIA GeForce GTX 960M (31.0.15.3141), GLES3

Issue description

GPUParticles2D are not displayed when exporting for web. CPUParticles2D appear to work as expected but the GPUParticles2D displays nothing upon playing the exported project in a browser.

I've tested in Chrome and Firefox using both Forward+ and Compatibility renderers which all produce the same result for me. Additionally, I've tested a similar project exported using Godot 3.5.2 GLES3 and found that both particles are displayed and emitting correctly in that version.

Steps to reproduce

1. Create a new project using either Forward+ or Compatibility renderer
2. Create a main scene with Node2D as the root node
3. Set up a CPUParticles2D node and a GPUParticles2D node as child nodes
4. Export for web with default settings
5. Deploy a dev server to play/debug the exported web project

Minimal reproduction project

Web Particle Test.zip

[Calinou]

Can you open developer tools (F12 or Ctrl + Shift + I), reload the page and paste the console output here?

I've tested in Chrome and Firefox using both Forward+ and Compatibility renderers which all produce the same result for me.

Only the Compatibility rendering method can be used in HTML5, since there's no stable API to run Vulkan on the web yet. Trying to use another rendering method will always use Compatibility once you export to HTML5 (check the Project Settings).

[Sammy-T]

Trying to use another rendering method will always use Compatibility once you export to HTML5 (check the Project Settings).

I figured they were the same output but I didn't know there was a setting there. Thanks for the heads up.

And I hope you don't mind I saved the log to a file. It would've been a crazy long comment otherwise.
localhost-1679612291758.log

[cody82]

I can reproduce this. GPU particles do not work in web export because of some shader issue:

Maybe this is the problem?

godot/drivers/gles3/shaders/particles.glsl

Line 308 in ba27db3

continue;

[cody82]

How can I change this file in the build? I modified it, recompiled and I get the same error in an exported game.

[cody82]

Never mind, I got it. Here is the fix:
master...cody82:godot:fix-html-particle-shader

[Calinou]

@cody82 Please open a pull request against the master branch with your changes :)

Remember to modify your changes to follow the code style guidelines too.