(2019-12-17, 17:52)Travis Cobbs Wrote: OK, I finally think I understand. I think what we really want to do is rotate the arbitrary p1pn vector around the sphere's axis until it lies on P2, and then measure the resulting angle between p1p2 and p1pn'. Does that sound right? And if so, do you have a suggestion on the best way to describe that in the spec?
I think this is the same as what I called "longitude / latitude mapping" in earlier posts (e.g. https://forums.ldraw.org/thread-18219-po...l#pid18221)
It chooses the dominant axle and rotate the base vector along with it when calculating the other. This way you can go all around using a single texture meta block.