guards need their position inside a pair of waypoint boxes (else the game removes them): placing a guard gives it a box and event bit 0, check and inspector state with box around it button; exit and object checks use the engine's cell rule (tiles listed in the cell, swap models), tile cell from the map loader formula

notes/geometry.md

@@ -114,7 +114,9 @@ Order in the file:
 
 1. `u32 N (tiles), u32 W, u32 H` (grid)
 2. **A**: N × `{f32 x, f32 y, f32 z, u32 rot, u32 model, u32 animFlag}` (export space; x,z = cell centre .5).
-   Only used to sort into the cell lists: cell = floor(x) + floor(−z)·W.
+   Only used to sort into the cell lists: cell = ftol(x − 0.5) − ftol(z + 0.5)·W (ftol truncates; 0x42ad4a,
+   constant 0x56e158 = 0.5) = floor(x) + floor(−z)·W for cell-centred tiles (all originals). The player/strat
+   cell of the collision tests is x>>12, z>>12 (FUN_004036d0).
 3. u32 n + n×u32 (list, referenced by strats)
 4. u32 n + n×90 bytes (lights/cameras? – objects.md)
 5. u32 n + n×34 bytes (path nodes)