nx_supports.nx

nx_supports.nx -- overhang detection for FDM 3D printing. v1 algorithm: for each vertex of the CURRENT layer's polygon, check whether that vertex is supported by the PREVIOUS layer's polygon (geometric expansion of prev by overhang_tolerance to account for the maximum unsupported overhang angle). Unsupported vertices need support pillars from below. Per cardinal NISHI_3D_PRINT_ROADMAP §2.1 axis 1 (physics-aware supports): v1 is conservative -- detects only vertex-position overhangs. v2 will add yield-load model + tree pathfinding + branching topology, ALL composing v1's detection output. Overhang tolerance: For a 45° safe overhang at layer height h, a vertex can extend h * tan(45°) = h sideways without support. Caller passes the tolerance directly (typically equal to layer_height_q14). Composes nx_polygon (offset for the "supported envelope" of prev + point-in-polygon for membership test). First-layer handling: if prev_polygon is NULL (a 0 pointer cast) the layer is treated as bed-supported -- no overhang verts. Christus-specific motivation: the outstretched arms appear in a layer where they have no support in the layer below. Without supports they bridge across air and sag. This primitive detects where the arms start so v2 can generate pillars. license_tier: ORIGINAL