** SEGA GENESIS / MEGADRIVE Software Scaling + Rotation ***
Sega Megadrive can't scale backgrounds and rotate sprites in software at the same time ?? - hold my beer !!
After Scaling I've been tinkering with Rotating sprites in software and I think it looks pretty sweet !
In the video 4 * 32x32 sprites are rotated through 64 steps at 30 FPS in software, it could be 60 FPS and more rotating objects if we were not doing the scaling at the same time but even blast processing has its limits

Rotation at 30 FPS is far smoother than you typcially see in even in pre-rendered rotations anyhow ( a 64 frame 32x32 rotation is 32kb - not small ).
Challenges were make it fast : very fast as this needs to work at pixel level, not double pixel like scaling. The megadrives packed pixel format (2 pixels per byte) makes that a little bit tricky . When I started the algorithm was 3x slower than now.
Make it sensible : has to be usable in game , had to present a rom size reduction over pre-rendered animation.
Make it flexible : so we can rotate frames in the background using up idle cycles (end of frame) and store those frames to vram for very heavy cpu scenes, so we can still have very smooth rotation with very heavy cpu demands still.