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Floating-origin: rebase cloth/vehicle/navmesh/terrain-streamer + 50 km² scale validation (#429 follow-up) #613
Description
Follow-up to the floating-origin / origin-rebasing first slice shipped in #612 (part of umbrella #429).
The first slice (Scene::RebaseOrigin / JoltScene::ShiftOrigin, opt-in WorldOriginSettings, default off) shifts root entity transforms, Jolt rigid bodies + static terrain + character controllers, and Box2D bodies back toward the origin when the primary camera travels far, keeping stored f32 coordinates small. It composes with the already-shipped camera-relative rendering.
Deferred from the first slice
Subsystems that hold world-space state outside the rebased set and so desync on a rebase (each documented as a limitation in JoltScene::ShiftOrigin):
- Cloth soft-bodies — JPH soft-body particle clouds are not shifted (SetPosition semantics for soft bodies are unclear; a wrong shift is worse than none).
- Vehicle / constraint anchors to a fixed world point — two-body constraints stay consistent (both endpoints translate together), but a constraint anchored to an absolute world point would not.
- NavMesh — baked in world space; agents would path in a shifted frame against an unshifted mesh. Needs the navmesh + crowd query frame to rebase too.
-
TerrainStreamerper-tileWorldOrigin(TerrainTile.h) — set but not applied at render; the natural place to fold the rebase offset in.
Scale validation (the umbrella's acceptance bar)
- End-to-end 50 km² traversal: no jitter/shadow-swim, physics stable across many rebases, streaming interoperates. The first slice proves the mechanism at a smaller distance (45 km visual evidence + Functional physics); this is the full-scale sign-off.
- Auto-trigger tuning under real traversal (thresholds, rebase frequency, cost of a rebase over N thousand entities).
Notes
WorldOriginSettings.Enableddefaults off (opt-in per scene), so none of the above affects existing scenes today.- Keep World: large-coordinate support — camera-relative rendering / floating-origin to kill far-from-origin jitter #429 open as the umbrella until this + the scale validation land.
Labels feature,performance for freeze-eligibility, matching #429.
Reacted by coderabbitai
Activity
coderabbitai commentedon Jul 10, 2026
🔗 Related PRs
#468 - feat(physics): wire Jolt HeightFieldShape into terrain collision (
#428) [merged]#562 - Perf/DOD: flat depth-sorted hierarchy world-matrix propagation pass [merged]
#587 - Camera-relative rendering + absolute-world pattern shaders (
#429) [merged]#601 - feat(renderer2d): camera-relative CPU-bake coordinate shift for 2D sprites (
#429) [merged]#612 - feat(scene): floating-origin / origin-rebasing (
#429) [merged]#663 - Floating-origin: rebase cloth/constraints/navmesh/terrain-streamer + 50 km² scale validation (
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fix(review): missing-safe pulley entity lookup + MD018 doc reflow (#613)
drsnuggles8 commentedon Jul 18, 2026
Landed in PR #663 (
feature/floating-origin-rebase-613). Per-item evidence:JoltScene::ShiftOriginshifts each soft body's COM (SetPosition, particles are COM-relative), andScene::RebaseOriginshifts the absolutem_ClothRuntimeCPU render cache. Guard:WorldOriginRebaseClothTest.ClothVerticesShiftRigidlyWithRebase.JoltScene::ShiftWorldAnchoredConstraints:NotifyShapeChanged(sFixedToWorld, -delta)shifts single-body-to-world anchors exactly in place (preserving rest state/motors/warm-start); pulleys are rebuilt from their shifted authored pivots. The defer-the-whole-rebase fallback was removed. Vehicles need nothing (theVehicleConstraintholds no absolute anchor; the chassis is a regular body already shifted). Guards:WorldOriginRebaseWorldJointTest,WorldOriginRebasePulleyTest.Scene::RebaseNavigationregenerates the mesh at the shifted bounds (Detour has no in-place translate —m_origis private and drives every spatial query), shifting bounds/off-mesh-links/agent-targets and rebuilding the query + crowd via a sharedBakeNavMesh(). Guard:WorldOriginRebaseNavTest.AgentContinuesToTargetAcrossRebase.WorldOrigin— folded into the per-tile draw (entityTransform × translate(WorldOrigin)) at every draw/shadow site and the non-tess cull frustum; made entity-relative via an entity-local camera feed so it's rebase-free. This also fixes the pre-existing streamed-tile stacking bug. Single-tile terrain is byte-identical (verified rendering correctly in the editor).WorldOriginRebaseVisualEvidenceTestat 50 km + a multi-rebase traversal: no visible pop (RMSE before/after 1.635, worst consecutive 1.545, both < 5.0).WorldOriginRebaseTraversalTestfires ~10 rebases across a 10 km flight and asserts absolute-trajectory continuity.WorldOriginRebaseBenchmark: 68.7 ms @ 10k, 308 ms @ 50k entities (Debug/unoptimized); rebase frequency validated by the traversal test (~1 rebase / grid cell at threshold 1024).17/17 tests pass (incl. the GL visual-evidence tests, which render rather than skip). Design notes captured in
docs/agent-rules/floating-origin-rebase-subsystems.md.Closing — the checklist is complete. Umbrella #429 closed alongside.
fix(ci): exclude vendored recast from UBSan signed-overflow (#613)
docs(ci): reference upstream recast overflow issue/PR in the UBSan ex…
Merge pull request #663 from drsnuggles8/feature/floating-origin-reba…
ci(tsan): suppress Jolt's assert-build mutex-bookkeeping race (vendor…