I know for the helicoptor level in Gunstar Heroes, it was vertical tile scrolling + line scrolling, but what about the smaller multijoined sprites? Sometimes during the 7-force boss, when the robot shaped like a gun shoots at a funny angle, the sprites that are making the gunbarrel are not in a straight line. Could have Treasure just used tons of prerendered rotation frames like everybody else did, and they just pretended that they actually did it in software?
The fact that it's a multijointed sprite gives it away. Round sprites don't need to be rotated, and straight sprites are predrawn at several angles from 0-90 degrees. All other angles can be displayed through hardware sprite flipping.
It's pretty obvious they did that, since the Mega Drive/Genesis can't do hardware rotation. Talented programmers can work around a lot of hardware limitations, just look at the Saturn games that have "transparencies" :nod:
I've seen rotation being done in a lot of Genesis games. I don't know if that's what they did, but I think some people faked rotation by building the rotating sprites out of smaller sprites, and adjusted the placement of the smaller sprites a little to give the illusion of rotation, and before it gets too obvious, they use another frame, (lets say 22.5 degrees) and do the same with that.
you do not have to scale and rotate things on the fly... in Treasure games, the stuff is either pre scaled or rotated into RAM/VRAM or its already so in the ROM... I think its the first way, since there are usually no artistic measures taken...
I don't believe it's technically possible to do all the sprite rotation/scaling in realtime. The only time it would be reasonable to do sprite rotation/scaling in realtime is if you ran out of v-ram AND you ran out of work ram AND you ran out of cartridge memory.
