72921a1e43
Rewrite the current range-tree API used by dyn-topo undo to avoid inefficiencies from stdc++'s set use. - every call to `take_any` (called for all verts & faces) removed and added to the set. - further range adjustment also took 2x btree edits. This patch inlines a btree which is modified in-place, so common resizing operations don't need to perform a remove & insert. Ranges are stored in a list so `take_any` can access the first item without a btree lookup. Since range-tree isn't a bottleneck in sculpting, this only gives minor speedups. Measured approx ~15% overall faster calculation for sculpting, although this number time doesn't include GPU updates and depends on how much edits fragment the range-tree.