Creepy Purple Head Is Creepy

This took a lot longer than I hoped. This post is about level of detail. That's where you take out some polygons and simplify a shape, usually based on how far away it is from the viewer, to save your graphics card the trouble of calculating things for polygons which are so small they only cover a few pixels or less anyway. I've had spheres doing this in my "engine" for a long time, because for spheres it's relatively easy to calculate the appropriate low(er)-poly mesh or meshes. For general meshes though, the easy approach is to create a mesh for each LOD using external tools or by hand. I was thinking of taking an automatic approach to generating these meshes and calculating the appropriate view distances. This would, in my mind, save me the trouble of having to do this outside the engine and tune each model's selection of meshes. (It would also save me from the problem of how to handle shape keys on lower-poly versions of a mesh, although I'd probably just ignore that.)

So, after finishing up fog and transparency illumination in the last post, I noticed that my sphere LOD scales seemed to be a bit off, so I started debugging. That led to bug fixing, and that led to me starting to implement that auto-LOD-generation that I had been thinking about. Like I said, it turned out to take longer than I had hoped. Part of this was finding some reasonably fast and simple algorithm to implement, and part of it was discovering things like Blender had output a separate vertex for every triangle corner in my mesh, even though most triangles share corners with other triangles. This meant a detour to merge these vertexes so I could do a bit of topology analysis in the algorithm (also incidentally saving a bunch of memory after merging the vertex data, although I guess that's not such a big deal compared to things like texture memory).

The final effect is shown in the video above. It works... Ok? I guess? The effect is exaggerated for testing in the video, and normally the changes are basically invisible. I think simplifying material shaders for distant objects will probably be a bigger win (and I'll see if I can automate that too). But anyway, now you know how I spent the last couple of weeks and why clouds still aren't implemented.