Triangulating contours into 2d mesh with color data intact

I am using a Javascript library 'Tess2' to triangulate a series of contours.

https://github.com/memononen/tess2.js/blob/master/src/tess2.js

It generates a perfect 2d mesh of any shape consisting of multiple contours:

A contour consists of a series of points (in a negative winding order for solid fills, in a positive winding order for holes)

However, the resulting triangles output by the algorithm are no longer tied to a contour and its fill color.

How would I alter Tess2 (or any other javascript library that tesselates contours) to allow for the retention of color data in the resulting triangles?

I've tried looking everywhere and I cannot find a solution.

After many failed attempts I finally got there.

I've been trying all this time to try and process a huge amount of contours all at once with a single tessellation pass. I tried editing the tessellation library to make each half edge retain it original contour ID. I had several eureka moments when it finally seemed to work, only to be disappointed when I stress tested it and found it to be less than perfect.

But it turns out I've been incredibly daft... All I had to do was group each contour with a particular fill, and then tesselate each group independently.

I didn't understand that for every interior contour fill, there would always be an opposite contour that effectively enclosed the outer contour loop. For instance, to represent a red box with a blue box inside there would be 2 red contours and 1 blue. I thought it could be represented with only 1 blue contour and 1 red, where the blue would also represent the red contour's hole, and so processing each colour group of contours independently didn't make sense to me.

When I finally realised this, I figured it out.

I've published a solution on github but I'm not sure how much use it is to anyone:

https://github.com/hedgehog90/triangulate-contours-colour-example

I've included a pretty comprehensive exporter script for converting contours (including curves) into polygonal paths for Adobe Flash/Animate which might be useful for someone.

I will be writing an OBJ exporter on top of this shortly, so I can represent vector graphics in a 3D engine.