How to generate live heatmap over a GLFT Model using user's gaze data

I’ve a GLTF Model and user’s gaze data. I want to kind of paint heatmap over my gltf model based on the data something similar as shown in image below.


I tried to use ray casting to get the intersected uvs and then using canvas for drawing heatmap at the intersected uvs and then converting canvas to a texture and applying texture to the model but heatmap was not being drawn at correct intersections. Also, uvs I am getting are not always in range [0,1].

I was creating separate texture for every intersected mesh but later I found that this approach is not going to work because if I am drawing heatmap at corner of a mesh then it won’t continue to adjacent mesh.

What is the best possible way to achieve this? I want to make sure that the approach works for all the models if we have corresponding gaze data.