I have a 3D geological model. I would now like to project a 2D map onto its surface; however the map only covers some parts of the 3D model surface. Currently I have set repetition off; but the effect is that parts of the 3D surface which are not covered by the map get colour assigned from the map border. The effect is quite ugly - see the right hand part of the image below.
Is there a way to make a texture translucent when the texture coordinates fall outside the [0,1] range? Or alternatively, could I assign a constant colour in this case?
Thanks for your help!