How to get position on mesh from texture position?

Questions
1

I have a texture projected on a mesh using decal.
I’d like to map the texture pixels to the mesh geometry position, how can I do that?
the goal is to be able to extract a mesh geometry position or even the face contained that position which is mapped to the a position in the texture.

2

Um, that’s a very unusual request. Can you please explain your use case a bit? Why do you need this logic?

3

sure,
let’s say I’m using a decal to project on a model an image with several drawings on it (for example polygons or circles).
I know the model position of the image center as it projected on the model in specific position, and assume I know the image drawings 2d image position or offset from the image center.

I would like to convert those 2d positions to the model positions as they are projected on the model and add some objects on that exact positions.

4

Um, have you tried to compute the coordinates of these 2D image positions in world space? What happens when you multiply a 2D image position with the world matrix of the respective decal?

5

didn’t tried it,
the idea of the decal is to get the shape of the model and this shape is not a surface, therefore different image positions lays on different faces with different normal vectors - will result different matrix

6

Give it a try and see what happens :wink: