[p5.js 2.0+ Bug Report]: p5.strands can't finalColor.set(c) for passed uniformVec4

[nbogie]

Most appropriate sub-area of p5.js?

• Accessibility
• Color
• Core/Environment/Rendering
• Data
• DOM
• Events
• Image
• IO
• Math
• Typography
• Utilities
• WebGL
• WebGPU
• p5.strands
• Build process
• Unit testing
• Internationalization
• Friendly errors
• Other (specify if possible)

p5.js version

2.2.3

Web browser and version

chrome

Operating system

mac

Steps to reproduce this

Steps:

1. run https://editor.p5js.org/neill0/sketches/dfBPlTGnb
2. observe error:

"An error occurred compiling the fragment shader: ERROR: 0:321: 'HOOK_getFinalColor' : Function does not return a value"

The generated glsl is:

vec4 HOOK_getFinalColor(vec4 color) {
}

Snippet:

set a 4-element array with setUniform

myShader = buildMaterialShader(prepShader);
shader(myShader);
myShader.setUniform("c", [1, 0, 0, 1]);

then in the shader setup, trying to pass it straight to .set() doesn't work

  let c = uniformVec4("c");
  finalColor.begin();
  finalColor.set(c);
  finalColor.end();
}

...but this would work:

  let c = uniformVec4("c");
  finalColor.begin();
  finalColor.set(c.xyzw);
  //or
  // finalColor.set([c.x, c.y, c.z, c.w]);
  finalColor.end();
}

(We get the same for filterShader's filterColor.set())

I'm just reporting. I don't think I can work on this.

[davepagurek]

Turns out this is already fixed in dev-2.0! https://editor.p5js.org/davepagurek/sketches/86ni5JKES

The problem was that the first node's id is 0, and when I was stepping through your sketch, I came across if (rootNodeId) { backend.generateReturnStatement(...) }, and 0 is falsey.

Thankfully, on dev-2.0, we have:

p5.js/src/strands/strands_codegen.js

Lines 73 to 75 in d3bb21c

	if (rootNodeID !== undefined) {
	backend.generateReturnStatement(strandsContext, generationContext, rootNodeID, returnType);
	}