Originally Posted By: Loremaster
How does the engine compute th BB?

It does not compute them. There are default values for these. See the manual: http://www.conitec.net/beta/aentity-min_x.htm

When you call c_updatehull the engine iterates over all vertices and if they lay outside the current bounds the bounds are updated to include the current one. But that is just a guess!

Originally Posted By: Loremaster
Those in the pic (and others) are way off in their dimensions.
Did you call c_updatehull for them without writing to min_x ... max_z afterwards?

Always learn from history, to be sure you make the same mistakes again...