The same-plane check projected vertices onto the dominant face
normal (n_a) to determine if two elements span the same depth
range. This correctly rejected slabs stacked along their normal
axis but broke for elements whose largest face is perpendicular
to the camera (e.g. X-normal boxes in plan view) — projection
onto X produces zero overlap for legitimate side-by-side pairs.
Replace n_a projection with projection onto _cam_look. Elements
at the same camera depth produce overlapping ranges and are joined;
elements separated in camera depth produce disjoint ranges and are
correctly rejected regardless of the orientation of their faces.
Generated with the assistance of an AI coding tool.
Ryan Schultz
6c993ba919