Relative amount each world box is grown by, so rounding cannot make a ray
miss the box of an instance it touches: the store into f32 (half an f32 step)
and the ray's move into object space on the GPU. It is a fraction of each
axis's summed term magnitude (see transformBounds), counted the same
way as the GPU gather's BVH_INSTANCE_BOX_PADDING (gpu-instance-box.ts)
and equal to it: 2^-20, 8 to 16 f32 steps of the largest term.
Relative amount each world box is grown by, so rounding cannot make a ray miss the box of an instance it touches: the store into f32 (half an f32 step) and the ray's move into object space on the GPU. It is a fraction of each axis's summed term magnitude (see transformBounds), counted the same way as the GPU gather's
BVH_INSTANCE_BOX_PADDING(gpu-instance-box.ts) and equal to it: 2^-20, 8 to 16 f32 steps of the largest term.