I had a cube, Now I want to create a door on a wall by using csg subtract, but I don't know how to create the door? Could you tell me detail?
thanks so much

you should check out the tutorials acknex has.

http://au.conitec.net/

go to tutorials and look for some of the basic ones. maybe " 3DGS basics for A6 "

the tutorials and manual may seem like a lot but reading them makes it all a lot easier.

basically what i do is take the same block you used to create the door way and make that your door. this way your door is the same size as your door way. to make that block a door copy it open a new level and paste it in the level. add your texture and place the orgin of the map where you want the door to swing from. the orgin is where the x and y axis meet. save the level as door and build the level. then back in your origional level add a map entity and find the door you just created. you can now attach a behavior to the door to make it act like a door.

i hope this helps