Line material with full color vertex support v141

Discussion
1

I needed this material and since it says vertexAlphas is not supported for LineBasicMaterial right off the bat, I had to hack it a little bit and that’s what I eneded up having and it works:

const vAlphaLine = (pnts, vclr) => {
	// pnts = [x1,y1,z1, x2,y2,z2, ...]
	// vclr = [r1,g1,b1,a1, r2,g2,b2,a2, ...] E [0,1]
	const geo = new THREE.BufferGeometry();
	geo.setAttribute('position',
		new THREE.BufferAttribute(new Float32Array(pnts), 3));
	
	const material = new THREE.LineBasicMaterial({
		transparent: true, // #undef OPAQUE
		vertexColors: true, // #def USE_COLOR
	});
	material.onBeforeCompile = function(shader) {
		shader.defines = { USE_COLOR_ALPHA: '' }; // vColor = vec4();
	}
	geo.setAttribute('color',
		new THREE.BufferAttribute(new Float32Array(vclr), 4)
	);

	return new THREE.Line(geo, mat);
};

What I want to mention here is that, judging by the code, USE_COLOR and USE_COLOR_ALPHA are meant to be mutually exclusive, like in this snippet:

#if defined( USE_COLOR_ALPHA )
	attribute vec4 color;
#elif defined( USE_COLOR )
	attribute vec3 color;
#endif

the culprit is in the vertex shader and it’s this:

#ifdef USE_COLOR
	vColor *= color;
#endif

this line of code forces me to enable USE_COLOR as well, so they are both enabled, which is not really logical because then this will work correctly:

#if defined( USE_COLOR_ALPHA )
...
#elif defined( USE_COLOR )
...

and this will not (if somebody writes it differently in the future):

#if defined( USE_COLOR )
...
#elif defined( USE_COLOR_ALPHA )
...

So I would like to suggest changing that line of code to

if defined( USE_COLOR ) || defined( USE_COLOR_ALPHA )
	vColor *= color;
#endif

it it doesn’t break anything else.