Storage of levels for bottom level bounding volume hierarchy

An apparatus for graphics processing, comprising:

• a memory;
• and
• at least one processor coupled to the memory and configured to:
• obtain a bounding volume hierarchy (BVH) structure comprising a plurality of levels and a plurality of nodes, wherein the plurality of nodes comprises a plurality of first nodes and a plurality of second nodes, each of the plurality of levels comprises at least one node of the plurality of nodes, and the BVH structure is associated with geometry data for a plurality of primitives in a scene;
• identify an amount of storage in a first memory that is available for storing at least some of the plurality of nodes;
• store, in the first memory, first data associated with the plurality of first nodes;
• determine, based on the amount of storage in the first memory and on a hierarchy of the plurality of second nodes, a number of top levels of the plurality of second nodes to store in the first memory;
• and
• store, in the first memory, second data associated with the number of top levels of the plurality of second nodes.