I know you can make a structure play a animation when a unit is built, but can you have a diff animation per unit? Like lets say I build supply truck.... on build it appears, a crane puts a box in the back, and it drives off. then i build a tank, and a animation plays where a guy gets in and drives off.
You could make the building create a dummy unit that has the animation and convert it to the normal unit after the animation is done. Sort of like gla's sneak attack.
what about the track marks on the ground or some other unit specific particle effects? the tank or truck that comes out of the factory via animation won't also use any locomotor, so if there's a hill in front of the factory it would look ugly when the unit drives through the hill or somethin' like that.
Well track marks I don't really know, but they don't show ontop of objects, only on the terrain, so I personally think that's minor. You could integrate it into the animation if you have a lot of free time :P.
For the specific particle effects you make the bones in the animation and set InitialDelay to when you want the effect to play (like sneak attack ... again).
As for the hill infont, you could just require the factory to have a "buffer zone" out the entrance. Almost how barracks do that to let the infantry get out. I'm not sure but it has something to do with the code right above the shadow code (Geometry prefixes).