Module world_query 

Per-voxel world queries against a .vxl column-slab world.

Port of voxlap’s getcube (voxlap5.c:937-962) — the engine’s random-access voxel lookup. Used by sphere/region edits (meltsphere, setrect, etc.) and any logic that needs to ask “what’s at (x, y, z)?” without going through a ray cast.

Voxlap’s slab format (mirroring roxlap-formats::vxl):

slab record:
  byte 0  nextptr  — advance to next slab in dwords (== 0 last slab)
  byte 1  z1       — top z of floor-colour list
  byte 2  z1c      — bottom z of floor-colour list MINUS 1
  byte 3  z0       — ceiling z (additional slabs); dummy in first
  <floor colours>  (z1c - z1 + 1) × 4 bytes (BGRA each)
  <ceil colours>   n_ceil × 4 bytes — ceiling colours of the *next*
                   slab (i.e. visible bottom of *this* slab's
                   solid mass, observed from inside the air pocket
                   between this slab and the next).

The ceiling colours sit between this slab’s floor colours and the next slab’s header — so they’re addressed at negative offsets from the next slab’s header, which is what voxlap’s getcube exploits via &v[(z - v[3]) * 4] with z < v[3].

n_ceil is derived as n_ceil = nextptr - 2 - (z1c - z1). Voxlap stores the negative of this as ceilnum = z1c - z1 - nextptr + 2 and uses it as a signed comparison threshold.

Enums

Cube

Result of a getcube query.

Functions

getcube

Look up the voxel at (x, y, z) in a column-slab world.