A read request to a ChunkSource, selecting source rows in one of two
ways:
Chunk (chunkIndex): the contiguous run
[chunkIndex·chunkSize, +chunkSize) of the chosen LOD, filled into output
rows [0, count). All passed buffers must have count equal to
meta.chunkSize for non-final chunks or the trailing count for the last.
Gather (indices/indexOffset/count): arbitrary source rows
indices[indexOffset .. indexOffset + count) of the chosen LOD, filled into
output rows [0, count). Indices need not be sorted and may repeat.
Gather underpins the LOD writer's "positions resident, heavy data fetched per
output chunk" pass — for a fixed-stride file source each row is a byte-range
read, so a unit pulls only its own gaussians (≈ 1× total reads, no whole-scene
residency). The two are the same operation with a different row selection; the
decode is identical, which is why a source serves both from one read.
The arms are disjoint on the indices key, so an implementation discriminates
with 'indices' in request (gather) vs the chunk path otherwise.
A read request to a ChunkSource, selecting source rows in one of two ways:
chunkIndex): the contiguous run[chunkIndex·chunkSize, +chunkSize)of the chosen LOD, filled into output rows[0, count). All passed buffers must havecountequal tometa.chunkSizefor non-final chunks or the trailing count for the last.indices/indexOffset/count): arbitrary source rowsindices[indexOffset .. indexOffset + count)of the chosen LOD, filled into output rows[0, count). Indices need not be sorted and may repeat.Gather underpins the LOD writer's "positions resident, heavy data fetched per output chunk" pass — for a fixed-stride file source each row is a byte-range read, so a unit pulls only its own gaussians (≈ 1× total reads, no whole-scene residency). The two are the same operation with a different row selection; the decode is identical, which is why a source serves both from one
read.The arms are disjoint on the
indiceskey, so an implementation discriminates with'indices' in request(gather) vs the chunk path otherwise.