the topic is pretty self-explanatory, I want to keep the original tank but in the mean time trying to create another unit that can transform back and forth

Besides Edmund Duke, I don't think it's possible.

Yeah, there's at least that other unit that can do it. It doesn't have to share the graphics/animations with the regular siege tank, so you could still give it some of its own, having its own siege/unsiege animations, etc.

Note that AI will not transform Duke Tanks under any circumstances afaik.

You could also possibly use Lift-Off for a transformation, if you want one of the forms to be flying. Or maybe Burrowing, if you have no cloakers.

I am interested in TZ's idea, but how exactly would you do a lift transformation?

There are lift off and landing animations, and there is a conditional jump for the lifted off state so that you can have different animations used when it is in that state. I don't really know whether units can use it or not, though. I haven't actually tried it myself.

I had an idea for how to do this but I can't figure out how to explain it, so I'm just going to give an example and hope you can figure it out. It would give the Vulture the ability to turn into a stationary turret. (You'd need to give it some spell and the vulture would transform when the player casts the spell. Also, the unit MUST use iscript.bin [NOT flingy.dat] control for its movement.)

Pick any two images, in addition to the Vulture. (I'll call them FormA and FormB for now.)

First, the iscript for the Vulture itself:



FormA's iscript:


And FormB's iscript:


Note that this has NOT been tested, but I've used something very similar.

Also, note that all three images (base unit, FormA, and FormB) will need to have the same number of frames. Also, any animation that one form can call must be defined for all three images. (eg. if you notice, FormB has Walking and WalkingToIdle animations.)

There are a few problems with this technique. First, the players will get the "Select Target" thingy, which would look somewhat stupid. Secondly, both forms will still be the same unit, which causes some weird problems. For one, if one form has an air attack but the other form doesn't, the form without the air attack will still try to attack air. Secondly, even if one form is immobile, it can still be ordered to move (but it won't actually move).

Are you sure you even need that first script? I think you could probably just use the form A or form B image/script directly. I don't think the initial image has to exist throughout the life of the unit, only that any valid image for the unit needs to still be associated with the unit.