I’m sorry if this is shading related.
I have this mesh. But I want to highlight only one cell/ grid like in the image.
Is there any example that’s available?
The grid cells you mention are faces - what you’re looking for is basically this example (but instead of a random mess of triangles you have a mess of triangles composed into a model 
), code in the bottom right.
Thanks @mjurczyk. It will be easy to raycast if these are all separate materials.
But from the model, it one material that has many vector points. Is there any way to
convert as each materials?