User asked how AC differentiates collidable vs phantom scenery.
The retail signal is at the Setup level: a Setup with NO
CylSpheres, NO Spheres, AND zero overall Radius is decorative
-- the player walks through it. retail header
docs/research/named-retail/acclient.h enum PhysicsState
includes ETHEREAL_PS = 0x4 / IGNORE_COLLISIONS_PS = 0x10 for
runtime-toggled flags, but the static signal for scenery is
the empty Setup collision arrays.
Pre-fix the mesh-bounds-fallback at
GameWindow.cs:4297-4429 ran on every outdoor scenery entity
regardless of Setup intent, then clamped the resulting
cylinder radius to >= 0.3 m. So small plants/grass got a
0.3 m collision cylinder and blocked the player even though
the Setup explicitly said no collision.
Fix: before the mesh-bounds fallback, check the cached Setup.
If it's a Setup-typed object (0x020xxxxx) AND CylSpheres /
Spheres / Radius are all empty/zero, mark it phantom and
skip the collision registration entirely. Non-phantom
scenery (trees with real CylSpheres or canopy-only BSPs)
still gets the mesh-bounds fallback so the player walks
under canopies but bumps into trunks. Raw GfxObjs
(0x010xxxxx, no Setup metadata) keep the old fallback
behaviour because they don't expose phantom intent.
Tests stay 1439 green.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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