Relative near-plane floor: near is never smaller than this fraction
of the (safety-expanded) scene bounding-sphere radius.
Why relative and not absolute: the historical absolute floor
(0.0001) silently broke tiny scenes — with the 1000x zoom-in
headroom, a scene of diagonal ≲ 0.1 world units lets the camera
orbit closer to the target than the floor itself, clipping all
nearby geometry. A floor proportional to scene scale keeps the same
zoom-in depth working at every scale.
The factor is chosen for continuity with the historical constant: a
typical diagonal-100 scene has expanded radius ~52.5, and
52.5 x 2e-6 ~ 1e-4 — exactly the old absolute floor.
Relative near-plane floor: near is never smaller than this fraction of the (safety-expanded) scene bounding-sphere radius.
Why relative and not absolute: the historical absolute floor (0.0001) silently broke tiny scenes — with the 1000x zoom-in headroom, a scene of diagonal ≲ 0.1 world units lets the camera orbit closer to the target than the floor itself, clipping all nearby geometry. A floor proportional to scene scale keeps the same zoom-in depth working at every scale.
The factor is chosen for continuity with the historical constant: a typical diagonal-100 scene has expanded radius ~52.5, and 52.5 x 2e-6 ~ 1e-4 — exactly the old absolute floor.