Make track styling configurable

[EdwardMoyse]

In ATLAS, we regularly want to make some tracks (e.g. Muons) stand out more e.g. with thicker lines. Ideally we should make this completely configurable, but right now I don't think we have a nice way to dynamically redraw tracks.

[EdwardMoyse]

One workaround I just tried, is to support a per-track "linewidth" property. This wouldn't make it configurable, but at least then the loaders could add this (or with manual editing of phoenix event data files).

[joyy-7921]

Hi @EdwardMoyse,

I reviewed your PR. The problem is,

In getTracks(), the TracksMaterial has a single lineWidth uniform (line 181 in tracks.ts), meaning all tracks in a collection share the same width. The JiveXMLLoader sets linewidth: 20.0 on individual track objects (line 281), but this property isn't being used by the shader-based rendering system.

Modify TracksMesh to support a linewidth attribute per track:

// In tracks.ts - TracksMesh
addTrack(points: Vector3[], color: ColorRepresentation, linewidth: number = 1.0) {
// ... existing code ...

// Add linewidth for each vertex of this track
for (let i = 0; i < points.length; i++) {
this.linewidths.push(linewidth, linewidth); // Two vertices per point
}
}

Then update the shader to use a linewidth attribute instead of a uniform, similar to how color is handled per-track.

If this approach seems correct to you, could you please assign the issue to me? I’ll take it from here.

Thanks.

[EdwardMoyse]

That all sounds very interesting! Of course, the issue with how to handle this in the GUI remains... but still, this sounds a lot more flexible than my hack. ;-)