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Undocumented features for advanced users ==============================

Collision detection
If the -nh build/shading option is given, a new collision system is
used for that level or map entity. The new system uses the variable
bounding box of an entity for collision detection, instead of the
fixed hulls, when the fat and narrow flags both are set. Note that
you have to adjust the bounding box normally for using that feature.
(This is not yet fully implemented. At some places, for instance
inside the office building behind the table, the new collision
detection does not work yet properly).

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