[p5.js 2.0 Bug Report]: WebGPU: antialias controls don't quite work like in WebGL

[davepagurek]

Most appropriate sub-area of p5.js?

• Accessibility
• Color
• Core/Environment/Rendering
• Data
• DOM
• Events
• Image
• IO
• Math
• Typography
• Utilities
• WebGL
• Build process
• Unit testing
• Internationalization
• Friendly errors
• Other (specify if possible)

p5.js version

Latest dev-2.0 build

Web browser and version

Chrome

Operating system

All

Steps to reproduce this

In WebGPU, we now only draw to a main framebuffer when it's necessary -- e.g. for a filter shader or when reading back/saving pixels. Currently, the main framebuffer is antialiased but the main canvas is not, so that we aren't unnecessarily double-antialiasing when we draw it to the main canvas at the end of a frame. However, if we are drawing directly to the main canvas before that, those drawn shapes will not be antialiased. Also, I don't believe setAttributes works yet in WebGPU, which in WebGL is how you can decide whether the main canvas should be antialiased or not.

So the task here would be:

• Support setAttributes({ antialias: true }) (or false)
• If antialiasing is enabled, antialias the main canvas only when drawing directly to it, and not when drawing the main framebuffer back to it

Note that this is a quite complex system to jump into, so while this is open for contribution, this is not a great first issue if you're just getting started.

[Piyushrathoree]

@davepagurek can you assign? I would like to work on this

[Anshumancanrock]

Hi @davepagurek , I've been looking through the codebase and I think I understand the issue.

The root cause seems to be that _shaderOptions() returns sampleCount=1 when there's no activeFramebuffer. But this path gets used for both direct drawing (UNPROMOTED) and blitting the mainFramebuffer (PROMOTED) and only the direct drawing case actually needs AA.

My idea is to use _frameState to distinguish between them:

• Add antialias to _webgpuAttributes defaults
• Create canvas-level AA textures (canvasAAColorTexture/canvasAADepthTexture) in _updateSize() when AA is enabled
• In _shaderOptions(), check if we're UNPROMOTED + antialias enabled → use proper sampleCount
• Keep blit path at sampleCount=1 since the content is already antialiased

This way we preserve the UNPROMOTED optimization while still getting canvas-level AA when needed.

Happy to discuss details if this approach makes sense! Could you please assign this to me? Thanks!

[Abhayaj247]

Hi @davepagurek , I want to work on this, assign to me

[davepagurek]

Thanks @Piyushrathoree, I'll assign this to you! Everyone else, thanks for volunteering too, feel free to help review the PR when it's up even if I haven't taken a look yet, community review is helpful too 🙂