| entity1 | registered entity pointer (Actor) | 
| entity2 | registered entity pointer (Actor), or NULL for collisions with the level when it was registered for physics. | 
| event | 
			NX_IGNORE_PAIR = disable collision events for this pair. NX_NOTIFY_ON_START_TOUCH = trigger event when the pair starts to be in contact. NX_NOTIFY_ON_END_TOUCH = trigger event when the pair stops to be in contact NX_NOTIFY_ON_TOUCH = trigger events permanently while the pair is in contact.  | 
	
pXent_settype(ent, PH_RIGID, PH_SPHERE); pXent_setcollisionflag(ent,terrain,NX_NOTIFY_ON_START_TOUCH); //trigger EventImpact on collision with terrain ent.event = EventImpact;
pXent_setcollisionflag( me, you, NX_IGNORE_PAIR); // no more collision events between me and you entities