processing/p5.js

setAttributes() invalidates references to earlier canvases

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#5,902 opened on Dec 16, 2022

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Area:WebGLBugHelp Wanted

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Description

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
  • Internalization
  • Friendly Errors
  • Other (specify if possible)

p5.js version

1.5.0

Web browser and version

107.0.1

Operating System

macOS 12.5.1

Steps to reproduce this

Calling setAttributes in WebGL mode might end up recreating the underlying canvas and renderer object.

Say you're trying to position the element, e.g. like this:

let canvas = createCanvas(100, 100, sketch.WEBGL);
// ...
canvas.position(0,0);

Unfortunately, this stops working after a setAttributes call, because after that call, canvas !== _renderer. Currently, to fix it, one would have to do:

createCanvas(100, 100, sketch.WEBGL);
setAttributes({ alpha: true });
let canvas = _renderer;
// ...
canvas.position(0,0);

Contributor guide

Research direction
Investigate the setAttributes function in p5.js to understand why it recreates the WebGL canvas and renderer. Propose a fix to ensure that existing references to the canvas element remain valid after calling setAttributes.
Tech stack
javascript
Domain
frontend
Issue type
Bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
JavaScriptGit
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
60