ReadonlyboundsBox around every primitive, [minX, minY, minZ, maxX, maxY, maxZ] (inverted when empty).
ReadonlyendReadonlykindReadonlymodeFor segments: how the entries pair up ('segments' for points, where it means nothing).
ReadonlynodeReadonlynodesnodeCount 64-byte nodes (GPU_LAYOUT_NODE_WORD); node 0 is the root. Empty for a tree of no primitives.
ReadonlyprimitiveReadonlyprimitivesprimitiveCount records in tree order: POINT_RECORD_BYTES or SEGMENT_RECORD_BYTES each.
ReadonlystartThe entries the tree covers, [start, end).
A primitive tree's data (the nodes in the GPU layout, the records in tree order).