WorldDef.enable_broad_phase_hybrid (default false; -bp=0/1 bench toggle):
an adaptive batch broad phase for high-churn scenes. When
move_count*4 > proxy_count, replaces the per-moved-proxy tree queries
(8k proxies x 3 root-descents on washer) with three BVTT self/cross
traversals (dynamic self + dynamic x static + dynamic x kinematic) that
share the upper-tree descent, plus an O(n) bottom-up refit instead of
the median rebuild. Both traversal and candidate-filter are parallelized
across the task system (per-worker buffers → merge → canonical sort by
(shape_a,shape_b,child) → deterministic contact creation).
Correctness: a #[cfg(debug_assertions)] SET-equality assertion (batch
candidate set == per-mover set) runs in every test and never fires — the
proof the BVTT finds identical contacts (the hash can't prove it since
creation order legitimately re-baselines). New test
determinism_broad_phase_hybrid_across_worker_counts. OFF hash 0x61E35C31
bit-identical; ON hash 0xBE99C5F7 identical across workers 1/2/4 +
external tasks. 180/186/180/180 tests, zero warnings, profile retrained.
Single-threaded washer -18.7% (17715 vs 21780, broad phase -51%) — beats
C (20661), within ~6% of Rapier (16844). DEFAULT OFF because it regresses
multi-threaded (washer w8 +52%): the batch materializes ~40-50k
candidates/step and serially merges+sorts them (a fundamental floor the
inline per-mover path avoids by filtering in the query callback), so at
w8 the parallel per-mover queries win. Cannot be worker-gated (would
break cross-worker determinism). Correct, deterministic, zero-cost when
off — an opt-in single-threaded accelerator for churn-heavy scenes.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
- WorldDef enqueue_task/finish_task/user_task_context (C contract incl.
null-return-means-inline); TaskSystem dispatch (Serial/Internal/External)
replaces the bare scheduler; determinism hash bit-identical through an
external thread-per-task system.
- examples/box3d: makepad app rendering the live simulation (offscreen 3D
pass with depth, orbit/zoom camera, instanced lit boxes/spheres, 204-box
pyramid + spheres, 4-worker solver, Space to reset).
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Port of the C threading design: worker threads with a fixed task ring and
help-while-waiting finish (scheduler.rs), atomic block-claiming parallel_for,
and the solver's stage machinery (per-block syncIndex CAS, sync-bits stage
advancement, mainClaimed race). Parallel narrow phase, broad-phase pairs,
sensors, finalize. Shared access goes through documented disjointness
primitives (sync.rs: SyncPtr/SyncSlice/AtomicIndex); worker_count 1 keeps the
serial path bit-identically. Results are bit-identical at any worker count
(determinism hash 0x7A796F4F asserted at 1/2/4 workers). 8 workers: 3.4-5.7x
over serial on heavy scenes.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
- contact solver wide ops + V32 now have real SSE2 and NEON paths selected
by target arch; scalar fallback behind the disable-simd feature. All three
paths are bit-identical (cross-arch determinism verified: same ragdoll
hash on NEON, SSE2 under Rosetta, and scalar).
- double-precision feature (C BOX3D_DOUBLE_PRECISION): f64 world positions
with the exact C boundary-function semantics; enables the far-from-origin
test halves (157 tests in DP mode, 151 default).
- world snapshots: recording substrate subset (buffer/writers/geometry
registry/readers) + world_snapshot.c port; bit-identical continuation
after restore, corrupt-image rejection.
- examples/benchmark.rs: all 10 C benchmark scenarios; serial Rust runs
1.05-1.55x slower than C -O2 at one worker (geomean ~1.3x with fat LTO).
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Full engine port in libs/box3d: math, geometry, GJK/TOI, hull builder,
dynamic tree, manifolds, constraint graph, solver (serial, scalar SIMD
path), all 8 joint types, sensors, mover, world API. 147 ported C unit
tests green in debug and release. See libs/box3d/README.md for the
upstream revision and sync notes, PORTING.md for conventions.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
