How to draw (heat map) something on arbitrary meshes using dynamic texture on the exact point I clicked?

[Evgeni_Popov]

@babylonlearn

(1) why does the cat don’t have proper texture coordinates?

The cat does have texture coordinates but not layed out for what you want to do to work. In your case, you need the uv partition to be somewhat “homogeneous”, meaning two points that are close on the 3D mesh should be close in the uv map, which is not always easy/possible to do.

@babylonlearn

(2) how can I make the cat to have proper texture coordinates?

You can try to use a DCC tool like Blender to modify the uv mapping. @PatrickRyan will know better than me about how to do that.

@babylonlearn

(3) does this mean that if a mesh doesn’t have proper texture coordinates, we cannot draw something on the surface of it on exactly where I clicked using dynamic texture?

Yes indeed. This method relies on mapping the dynamic texture over the mesh, so it relies on proper uv coordinates for the mesh.

@babylonlearn

(4) regarding my original post, I wanna know if there is a way to draw (something) only on the point I clicked on the surface of a random 3D mesh. (so decal doesn’t seem to be a good idea because I would like the texture for the main mesh (cat) to re-render every time I clicked. if I placed decal_1, is it easy to change decal_1 when I place decal_2? this is similar to heat map functionalities).

I’m not sure I understand the problem with decals… You can create any amount of decals and they are not related to each other: each decal is a separate mesh.

@babylonlearn

(5) my ultimate goal is to draw a heat map on a (random) 3D mesh. I probably don’t need to use dynamic texture to draw heat maps. Do you have any idea how to realize this?

So, decals are probably not a good idea as you want the texture to fully cover the mesh.

In the PG you did from Drawing on a Dynamic Texture over existing image it does work because the plane has proper uvs => I think it’s the right method, you simply need good uvs coordinates.