Adapting planar quadtree for sphere
Hi everyone,
I'm quite used to working with quadtrees for flat, 'infinite' terrain where I just have a coherent noise function that returns a height for a given x, z position and quadtree cells are split based on camera distance to their centre (where the centre takes into account the height as well).
I'd like to expand this to work for spherical planets using the common method of having 6 quadtrees which form a cube, then normalising the vertex positions to make a sphere. I have a few questions though which none of the tutorials for this seem to answer:
What coordinates should I use to sample my noise function? The raw (x, y, z) coordinates of the vertex positions in the cube, or should I use the same coordinates but after I've 'spherified' them?
What distance should I use to decide if quadtree nodes should split/merge? Should I use distance from camera of the node in its cube position, or should I work out where the node's centre is on the sphere and then use the distance to that?
Thanks for the help
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