Rename the streamer/sidecar transfer and record types to describe what
they are rather than how they move:
MeshChunk -> StreamedMesh
InstanceChunk -> StreamedInstance
InstanceCpu -> InstanceInfo
PackedElementInfo -> ElementTableRecord
uploadMeshChunk -> uploadStreamedMesh
uploadInstanceChunk -> uploadStreamedInstance
buildMeshChunk -> buildStreamedMesh
and the two post-index sidecar metadata blocks:
"critical" metadata -> "geometry" metadata (meshes/instances/georef/TOC)
"deferred" metadata -> "element" metadata (elements + string table)
parseSidecarCritical -> parseSidecarGeometryMetadata
parseSidecarDeferred -> parseSidecarElementMetadata
The one behavioural change: the element hierarchy (parent_id) was
carried through ElementInfo, ElementTableRecord, and the sidecar element
table but never consumed, so drop it and bump SIDECAR_VERSION 16 -> 17.
No back-compat: regenerate sidecars. sample.ifcview is regenerated at v17.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
The .ifcview data is hugely redundant (repeated double instance matrices,
patterned indices) — measured 12x zstd whole-file. Server Content-Encoding
can't be used (it breaks HTTP Range), so compress PER-CHUNK into the format.
Format (v16): geometry becomes per-chunk zstd(vertices)+zstd(indices) frames —
each independently Range-fetchable, so streaming is intact — and the critical +
deferred metadata blocks are single zstd frames. SidecarChunk carries the
compressed blob offsets/sizes; applyStreamedChunk (render/upload) is UNCHANGED —
decompression slots into the fetch. Full readSidecar (test/tooling) reconstructs
by decompress+scatter. zstd: desktop links libzstd (also compresses at bake);
the web build (Emscripten has no zstd port) FetchContent's the pinned zstd
source and compiles its decompress-only subset for wasm — no vendored blob,
same version as desktop. New SidecarCompress wraps it (compress guarded off
under Emscripten). Both stream paths — desktop StreamingThread worker + sync
fallback (readChunkGeometryCompressed) and web beginWebChunkLoad — decompress;
readSidecarMetadataOnly / the web bootstrap / loadDeferredMetadataWeb decompress
the metadata blocks. streamingByteProgress reports COMPRESSED bytes. MEASURED: a
752 MB v15 federation → 75 MB v16 (10x; per-file 6.7-15.3x); PP-PLP 118→15 MB,
loads 13/13 chunks on web, 0 errors.
Three fixes found while testing big federations on a real server:
- Web-streamed race: streaming_from_web was set in the deferred-header callback
(a round-trip after the model+chunks exist), so driveStreamingLoads could take
the sync fopen path meanwhile → "failed to read/decompress chunk 0". Now set
immediately after applyCachedModel.
- OOM abort on 18 models: the pool grew unbounded until an alloc failed, but on
web that's an uncatchable bad_alloc abort. Cap total pool capacity
(setMaxTotalCapacity, 3 GB) so it stops before the heap ceiling, and raise
MAXIMUM_MEMORY 2→4 GB (wasm32 max) for headroom.
- Web never evicted (grow-or-block only). At the hard budget, fall through to the
LRU/priority evictor so a big federation stays navigable (highest-contribution
chunks win) instead of freezing with holes.
113/113 desktop + 6/6 web smoke pass. No back-compat: regenerate sidecars
(desktop bakes v16; scratch conv tool migrates v15→v16).
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
First-paint over a network is metadata-bound: the whole post-index metadata
(~10 MB on a 118 MB model) had to download before any geometry. But ~25% of
it — elements + string_table, the IFC element tree (names/GUIDs/hierarchy) —
is used only for UI/picking, never for rendering (ViewportCore never touches
it).
v15 splits the post-index metadata into a render-CRITICAL block (meshes,
instances, georef, chunk TOC) preceded by its byte length, then a DEFERRED
block (elements + string_table). The web loader reads only the critical block
before painting; the deferred block sits at a known, self-describing offset
([critical end, EOF)) and is fetched on demand. Desktop reads both (local).
Web on-demand path is wired and complete (not yet called — no UI consumer):
loadDeferredMetadataWeb(model_id) range-fetches + parses the deferred block
into ModelGpuData.elements/string_table, at most once; the first consumer
will be "show the selected object's name" on pick. No background prefetch —
view-only sessions never download the property data (saves 2.64 MB on this
model).
parseSidecarTail split into parseSidecarCritical + parseSidecarDeferred (pure,
unit-tested); StreamingSidecar gains the critical-block locator. Measured
(118 MB model): critical metadata 10.35 -> 7.71 MB, deferred 2.64 MB off the
path; first paint 10.5 -> 9.6 s @ 24 Mbps. (Instances still dominate the
critical block — the next metadata lever.) Format -> v15, no back-compat;
regenerate sidecars. 111/111 unit + 6/6 web smoke pass.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Splits the v13 metadata wire-format knowledge out of the FILE*-bound
streaming reader into pure, buffer-based functions so the web byte-range
path (#88) can reuse it without loading the whole sidecar into the wasm
heap:
- parseSidecarHead — validates the 16-byte head, yields num_vertex_bytes
- parseSidecarTail — parses meshes/instances/georef/elements/strings
from an in-memory tail buffer, bounds-checked
- planSidecarReadRanges + SidecarReadPlan — the range-coalescing /
scatter planner, promoted out of the anonymous namespace
readSidecarMetadataOnly and the range readers now call these; desktop
behaviour is unchanged (head + tail are small, the bulk is still skipped
via seek). The metadata tail is split from the head around the bulk
sections, so a blob-backed loader just slices those two regions and
hands the bytes to the same parsers.
Closes a coverage gap: StreamingLoader had no unit tests. Adds
test_streaming_loader.cpp (7 cases: metadata round-trip, corrupt/truncated
rejection, vertex+index range scatter, head validation, tail truncation,
read-plan coalescing). 107/107 unit tests pass.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Dion Moult