nx_mesh_decimate.nx

nx_mesh_decimate.nx -- mesh DECIMATION by dense-grid vertex clustering (Rossignac-Borrel 1993), pure integer. Marching-tetrahedra meshes are dense (many tiny triangles on flat faces); this snaps every vertex to a regular cell grid (cell-CENTROID representative) and drops triangles that collapse (>=2 verts land in the same cell) -> far fewer triangles for the SAME shape, with bounded error <= ~cell. The transfer/size EXCEED: a sovereign STL shrinks Nx with one tolerance knob, deterministically (integer). No hash needed (a dense bbox grid has no key collisions). Reuses nx_mesh + nx_mesh_print_check (bbox). HONEST: this is a SIZE/transfer decimation, lossy by <=~cell and not guaranteed watertight; closure-preserving decimation is a later rung. license_tier: ORIGINAL