[Arne]

The rainbow command alone is quite clumsy for setting up gradients, yeah. It's been a liitle while since I rainbowed, but I think you'd jist set up a 240 line list and then configure each line with Rain. I often would use it to line dither the sky gradient but it occured to me that one could use the effect for a tiny screen-wide copper bar that's a laser attack. You'd have to store the old background line values somewhere ofc. I don't think one would need to touch the more advanced COP commands. Colour index here would not be 0 black, whatever the sky ends up being.

I remember using rain to do a classic demo type rotating copper bar wheel once, which needed some LUTs for the rotation overlapping as there's no actual z-depth to a 1D array.



For sprites, I might have mentioned it, but I think I’d use those for decorative particle effects which tend to use less colours, and flicker won’t be an issue there. It's really a waste to do flat or low colour effects using bobs which then need to blit in 4 planes. I think with 50fps, one could alternate 8 3-color sprites to get 16 transparent ones. Little explosions, Kirby-style GET debris/stars and sparks (8). Collision puffs and trails behind the player (2). And the pickup scores (4). Maybe Enemy/Boss bullets (2). A vertical boss beam could be done using a single sprite.

Some of the 4 sprite palettes could flash in garish colours for sparks, whilst the BG palette remains static (colour animation here would require extra image frames unless certain blit modes can be used).

I think computed sprites can introduce a little slowdown (at least in interpreted mode) as they need to be computed.