P5.js: WEBGL TRIANGLE_STRIP not rendering correctly.

[Aierie]

4439 ## Most appropriate sub-area of p5.js?

• [ ] Color
• [x] Core/Environment/Rendering
• [ ] Data
• [ ] Dom
• [ ] Events
• [ ] Image
• [ ] IO
• [ ] Math
• [ ] Typography
• [ ] Utilities
• [x] WebGL
• [ ] Other (specify if possible)

Details about the bug:

• p5.js version: 1.0.0
• Web browser and version: Chrome, Firefox
• Operating System: MacOS Catalina
• Steps to reproduce this:
  With the WEBGL renderer, do

beginShape(TRIANGLE_STRIP);
  vertex(0, 0);
  vertex(50, 50);
  vertex(0, 50);
  endShape();
  beginShape(TRIANGLE_STRIP);
  vertex(-50, -50);
  vertex(0, -50);
  vertex(0, 0);
  vertex(50, -50);
  vertex(50, 0);
  endShape();

A triangle shape is produced, but stroke is only added on the first edge.

Resulting image:

Editor:

https://editor.p5js.org/Aierie/sketches/3xuXwEEiL

Works fine in version 0.10.2

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[matvs]

I would like to start working on this issue.

[Aierie]

Hey @matvs , I've found the root cause and am submitting a PR soon!

[matvs]

Hi @Aierie
I've just seen your comment, I should probably have waited for confirmation before starting working on this issue. My PR can be then rejected.

[Aierie]

No worries @matvs ! Just some coincidental timing. You can also close the PR yourself, would save the volunteers some work.