Shell-local axis-aligned bounding box, in the same coordinate space as
positions, as
[xmin, ymin, zmin, xmax, ymax, zmax].
World/model-space center used as the shell mesh origin.
Triangle index array for positions.
Bounding-sphere radius for projected-size LOD decisions.
Generation metrics.
Complete shell generation result.
Coordinate contract:
A runtime shell should therefore create geometry from positions and place the mesh at center. Do not add center to the positions before upload, or the shell will be translated twice.