docs(research): collision transition system pseudocode from decompiled + ACE
Cross-referenced ACE's Transition.cs, SpherePath.cs, CollisionInfo.cs,
BSPTree.cs, BSPNode.cs, LandCell.cs, EnvCell.cs, Sphere.cs against the
decompiled retail client (chunk_00530000.c FUN_005387c0, FUN_00538180).
Covers the full collision pipeline:
- FindTransitionalPosition (step subdivision, main loop)
- TransitionalInsert (per-step cell collision + response)
- FindEnvCollisions (terrain + indoor BSP paths)
- StepUp/StepDown (step height handling)
- AdjustOffset/SlideSphere (wall slide projection)
- ValidateTransition (post-step validation, FramesStationaryFall safety)
Documents which primitives are already ported in CollisionPrimitives.cs
and BSPQuery.cs, and catalogs what remains to be implemented.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
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