The any-hit walk's child order (TraceModuleOptions.anyHitOrder), when a
ray hits both children of a node. Every order gives the same answers; only
the work per ray changes.
'far' (the default): the farther child first. A shadow or probe ray
starts on a surface, so its nearer child mostly holds the geometry it
starts on, and its blocker lies ahead (T1.3: 1.1-2.8x faster than near
first on the surface-ray bench).
'near': the nearer child first, as closest-hit does.
'larger': the child with the larger box (surface area) first. A ray
that crosses the parent crosses a child with a chance in proportion to its
area (the SAH's own assumption), so the larger child is the likelier to
hold a blocker: a room's shell, a floor, a wall. It costs two box areas
per node where both children are hit. On compare/gpu's furnished room it
cut the slowest of 32 rays from outside from 78 box tests to about 24
(docs/internals/design/trace.md, "Any-hit child order").
It is one comparison in the same walk; switching back is setting the
option back (or leaving it out).
The any-hit walk's child order (
TraceModuleOptions.anyHitOrder), when a ray hits both children of a node. Every order gives the same answers; only the work per ray changes.'far'(the default): the farther child first. A shadow or probe ray starts on a surface, so its nearer child mostly holds the geometry it starts on, and its blocker lies ahead (T1.3: 1.1-2.8x faster than near first on the surface-ray bench).'near': the nearer child first, as closest-hit does.'larger': the child with the larger box (surface area) first. A ray that crosses the parent crosses a child with a chance in proportion to its area (the SAH's own assumption), so the larger child is the likelier to hold a blocker: a room's shell, a floor, a wall. It costs two box areas per node where both children are hit. On compare/gpu's furnished room it cut the slowest of 32 rays from outside from 78 box tests to about 24 (docs/internals/design/trace.md, "Any-hit child order").It is one comparison in the same walk; switching back is setting the option back (or leaving it out).