I tried to UV-map an altar. The top is basically a cube. Since it’s made of marble, I wanted the veins of the marble to run around the table uninterrupted.
I thought I had found a smart way to UV map, but the result wasn’t what I expected:
For that screenshot I replaced the marble by a test-texture that makes the problem quite obvious. The left shows a render. The right shows the UV mapping of the top of the table and the 4 vertical sides. You can see that the sides are not deformed like I expected, instead they are formed of two triangles and this makes weird angles.
The result in Blender and in Panda are identical, which is a very good thing.
Is there a way I can get the expected deformation?
I see what you are saying about the expected result, but it will not end up like that because when it gets computed on the video card it is actually two triangles not one quad. You could get closer to the expected result by adding another edge in the middle of the face (splitting it in half).
You would probably be better off to split the UVs on the corners so that the all the shapes are square in the UVs as they are in the geometry. That means that the “C” and “O” on each corner will be left uncovered. The result should resemble a fat “+” symbol.
It should look good with checkers, but it can look strange with lines:
Yeah, that’s the traditional way to do it.
You could also try adding a subdivision on the faces, like a plus sign through the middle of the table, that should reduce the distortion effect in the original UV layout.
Got it, I have to think in triangles. I guess that’s one of these situations where being lazy doesn’t pay. I took the time to make specific versions of my textures in Gimp for some of my models, instead of just hoping that a magical UV mapping will do it all for me. And it works . Thanks for explaining!