nx_mesh_qem.nx

nx_mesh_qem.nx -- mesh decimation by QUADRIC ERROR METRICS (Garland-Heckbert 1997), pure integer. Each vertex accumulates a quadric Q (sum of outer products of its incident face planes); collapsing an edge costs p^T Q p (the squared distance of the new point to those planes). Collapsing LOWEST-cost edges first => flat regions decimate hard while curved/feature regions keep their vertices -- the quality win over uniform vertex clustering (nx_mesh_decimate) on CURVED geometry. Sovereign + no-float: the mesh is scaled into a bounded [0,1024] cube so the integer quadrics never overflow i64; collapse uses MIDPOINT placement (no matrix inverse). Reuses nx_mesh + nx_isqrt. license_tier: ORIGINAL