I always read that T-Junctions were bad. I figured as long as the point causing the T-Junction was interpolated between the other two point it should look fine. Well... I was wrong. As seen in today's pictures the not only were they T-Junctions causing color problems they also cause seems on ATI cards (well atleast my ATI card).

The good thing was it was really easy to fix. There's only a maximum of 6 configurations the tesselation needs to be to fix up the T-Junctions so it was fairly simple to just add a few extra triangles to the list.

In other news I've modified the system to create a single vertex buffer from the unique point list so I can use index buffers. Also for this test I simply subdivided to a certain level of complexity instead of doing camera based subdivision so the index buffer isn't re-created every frame either. When I subdivide a lot I'm able to push 15 million triangles per second, and this is through a decently complex vertex buffer. Only when I render all 260k triangles (130k for planet, 130k for atmospher) twice (a second time for edges) does the frame rate dip a little below 60fps. This is also in C#, though since I have a static vertex and index buffers that shouldn't matter (keyword shouldn't). This is way beyond the worst case for the planet. The atmosphere should never have that many triangles.

I mentioned that the seems only appear on ATI cards, I have to systems that I develop on, one with a Geforce 6600GT and the other has an ATI X1600 Mobility. Go here for full specs. They're not the best but I'd prefer what I'm working on to be as backwards compatable as possible.

Enough ranting for today. Quick walkthrough the pretty pictures. Far left is simple the old version with the TJunctions. The next picture I just highlight the seem. Next is the Edge overlay to see the actual triangles. Then the T-Junctions are fixed and after I show the edges of the fix so you can see how it's patched up. The two images on the bottom row are the super tesselated versions with and without the edges shown.