Commit B of the instancing migration. The sidecar on-disk format is
reintroduced at version 4 with MeshInfo + InstanceCpu sections in place
of v3's flat per-object draw-info array.
After streaming finishes, MainWindow asks the viewport for a post-
finalise snapshot (VBO + EBO are read back from the GPU, meshes and
instances come from the CPU-side arrays) and writes it alongside
PackedElementInfo + the string table. On a subsequent load,
readSidecar rehydrates the whole struct and ViewportWindow::
applyCachedModel uploads VBO/EBO/SSBO in a single step, bypassing the
iterator entirely.
Staleness check is still by source file size.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Commit A of the instancing migration (Phase 3a). The streamer now runs
the iterator with use-world-coords=false and dedupes by the geometry's
representation id, emitting a MeshChunk once per unique geometry and an
InstanceChunk per placement. The viewport keeps geometry in local
coordinates (28 B/vertex, down from 32) and applies the per-instance
transform in the vertex shader via an std430 SSBO indexed by
gl_InstanceID + a per-draw uniform offset. After streaming finishes
finalizeModel() stable-sorts instances by mesh_id, assigns each mesh a
contiguous range, and uploads the SSBO; render then issues one
glDrawElementsInstancedBaseVertex per mesh.
BvhAccel is reshaped to operate on a generic BvhItem (world AABB +
model_id) so it can drive instance-level culling, but the path is not
wired in yet -- every instance is drawn every frame in this commit.
Progressive-during-streaming rendering is likewise disabled: a model
appears when its SSBO is uploaded, not incrementally. Sidecar cache
is stubbed (reads miss, writes are no-ops); the v4 on-disk format with
MeshInfo + InstanceGpu sections lands in Commit B.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Phase 2 performance: BVH acceleration with median-split build, per-model
trees, and EBO re-sorting for GPU cache coherence. Raw binary .ifcview
sidecar stores full geometry + BVH for instant subsequent loads (skip
tessellation entirely).
Per-model GPU buffers (VAO/VBO/EBO per model) eliminate cross-model buffer
copies on growth. Sidecar reads happen on a background thread. Bulk GPU
uploads are progressive (48 MB/frame chunks) so the viewport stays
interactive while multi-GB models stream in.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Dion Moult