A GPU builder if device has subgroups, tinybvh otherwise (or with no
device). prefer picks the GPU builder ('gpu-hploc', the default, or
'gpu-lbvh'), or forces the CPU builder ('tinybvh'), for comparisons.
The options of buildLayouts are the builders' common ones; H-PLOC's own
(its Morton codes and tie rule) keep their defaults here.
A GPU builder if
devicehas subgroups, tinybvh otherwise (or with no device).preferpicks the GPU builder ('gpu-hploc', the default, or'gpu-lbvh'), or forces the CPU builder ('tinybvh'), for comparisons. The options ofbuildLayoutsare the builders' common ones; H-PLOC's own (its Morton codes and tie rule) keep their defaults here.