Help me find out what this texture mapping technique is called I'm in the process of making a tool that requires rendered texture to follow the contours of a piece of clothing. An example would be this website https://knyttan.com/editor/jumper-editor/. The effect here is achieved by using a colour map:

I looked at the shaders that are used for this and it seems that the texture offset is calculated based on the colour channels from this map. 

Now I was wondering if this is a complete bespoke way of doing this, or if this is a known technique and if it is what is it called ?
What you see in the image called a UV map. That is, it is simply texture coordinates to be looked up encoded in a image. Same thing happens in all texture lookup in 3D there is a underlying sampler that picks where to pick texture color from.



Image 1: Image showing UV map of two overlapped triangles and sampled texture with same UV coords

Here are the sources for those images, please do not overwrite the sources.


Demo showing the UV map
Demo showing the texture