Add a decal to the clothes stain

I have a dress model that Stein has, when I put a photo on it using the decal geometric , it puts the photo behind and in front of Stein, even though I want one photo at all.

A bit hard to understand what you mean - could you share a screenshot of what you have vs a visualisation of what you’d like it to be?

Yes, the description is too vague.

It might be a decal that appears on the front and on the back of the model. If this is the case, the size parameter of the decal must be fixed, so that the decal projector penetrates the model, but does not exit from the back.

new DecalGeometry( mesh, position, orientation, size );