Depending on which entity types collide with which other, two different methods of Collision detection are used. For this each entity has both a Bounding Box and a box-shaped Hull. The hull is used for collisions of a moving entity against the level or map entities. This kind of collisions detect each polygon of the target entity. For all other types of collisions, the bounding boxes of the two entities are tested against each other. Bounding box as well as hull won't rotate with the entity, they are always xyz axis aligned.
While the bounding box can
have an arbitrary size, there are only three possible hulls: fat, narrow and
point sized. Entities with a point sized bounding box can pass all invisible
blocks (but not blocks that are visible, but have invisible surfaces through
the None flag). The narrow hull is a cube of 32 quants edge size around the entities' centre. The fat hull is a box of 48 quants vertical and 64 quants horizontal size, displaced upwards by 8 quants. These sizes match most requirements, but for some special cases they can be changed. Unlike the bounding box, they are not given individually per entity, but are stored in the level. They can be changed when compiling the level, by entering the following options in WED's Build Options line: