[p5.js 2.0 Bug Report]: lerp() not working in p5.strands

[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

2.2.2

Web browser and version

All

Operating system

All

Steps to reproduce this

Steps:

1. Go to https://beta.p5js.org/reference/p5/buildfiltershader/
2. Scroll to the fifth example, with the animated red-blue gradient
3. Replace mix with lerp
4. The sketch stops working

mix and lerp should act like aliases in p5.strands. mix does already work, but lerp does not for some reason, although I thought we aliased it already? It may have gotten lost in a refactor at some point.

Snippet:

let myFilter;
function setup() {
  createCanvas(50, 50, WEBGL);
  myFilter = buildFilterShader(gradient);
  describe('A moving, repeating gradient from red to blue');
}

function gradient() {
  let time = uniformFloat();
  filterColor.begin();
  filterColor.set(lerp(
    [1, 0, 0, 1], // Red
    [0, 0, 1, 1], // Blue
    sin(filterColor.texCoord.x*15 + time*0.004)/2+0.5
  ));
  filterColor.end();
}

function draw() {
  myFilter.setUniform('time', millis());
  filter(myFilter);
}

[nbogie]

also discussed in #7849
and done here and merged! #7875 #7887
so yeah, accidentally removed i guess

[avinxshKD]

Hey @davepagurek seems like mix is working, but lerp might not be properly aliased in p5.strands, possibly a regression from earlier changes. I can take a look

[YuktiNandwana]

Hi @davepagurek, I'd love to work on this!

I've been investigating the codebase in src/webgl/p5.Shader.js to find where the strands function mapping occurs. I see that mix is working but lerp isn't, so I'm looking for the specific object where these GLSL aliases are defined to add lerp: 'mix'.

Since I have my local environment ready and I'm currently contributing to another Typography issue, I can jump on this immediately. Could you point me to the right mapping object, and may I be assigned to this?