Shading and creased diagonals

I made my sculpty dodecahedron using 2 and a half quads for each face. This means one quad is shared between adjacent faces, with a crease along the diagonal. This makes the shape perfectly with a sharp edge along the diagonal. However, there appears to be an artefact of the shading and shininess that, presumably because this is done per quad and not per triangle. Thus the creased quad(s) are shaded differently from the faces to which their two triangles belong. This substatially spoils the appearance. It is especially marked with shininess, as in the picture, but affects un-shiny shading as well. The picture shows two dodecahedrons. Texture marks the quad edges brown and the diagonals green. The left one has interpolated vertices (to keep the tecture the same on LOD changes) and the right does not - that makes the effect even more obvious. I don't suppose there is any solution to this, as it must be a function of the rendering engine, but any views would be interesting.

PS - I notice there is another shading artefact that makes even the sharp edges (when you look along them) look rounded from other points of vew!

Nice job on the modeling. In any other environment but SL, those dodecahedrons would be perfect.

Careful texturing might help a little with the roundover problem, but you're still going to have soft normals on those diagonal edges (at least I think that's what's going on). To make SL a bit happier about the shape, the only solution I can think of is to make sure the edges of each pentagonal face have horizontal or vertical quad edges on them. In some places, that will mean doubling up.

Am I right in assuming that texture on the model on the lower right is a good representation of the wireframe? I'm guessing the gray lines are the horizontals and verticals, and the green lines are the diagonals, correct? If so, then you can probably eliminate the problem by bringing the center vertex to the corner on each offending face. See the picture below to see what to move where.



In theory, it should work. But the only way to know for sure is to try it.

Correct - the texture represents the wireframe exactly. I guess that's it ..the normals are per quad, not per triangle. Your solution could work, but I was trying to do this with minimal texture distortion, and it would spoil that. I have thought about tucking the "spare" triangle(s) just under the next one in the same face instead of sharing it with the next face. That way there would be minimal change in the normal. But I can't fit that in at 9x9. Probably I will sacrifice that LOD level and try it anyway!