My first MSX demo!

The screen 3 parts where the pixels are alternating between coloured and black, did you do that by design (to make the colours less heavy and solid) or is it also a trick for less calculating and updating?

@Edwin: indeed the vram access may be a severe penalty for the higher screen modes, but I guess that's partly overcome by the amount of VRAM you have and the tricks you can do on MSX2. I'm trying to think for example about how the disco dancefloor effect in the recent C64 demo Edge of Disgrace could be done in screen 5, making use of copying, hardware scroll (both x and y) and colour redefinition per line. Screen 4 is only possible if you use sprites to draw all the black lines (and I'm not sure if you can calculate and update the sprites fast enough); if screen 5 would succeed you could use these sprites for other effects (dancing people on the floor, to name something obvious).

@Artrag: for vertical zooming I suppose you could use line interrupt / vertical hardware scroll? Not for actual scrolling, but for displaying a certain line a number of times. That way you can zoom, and dynamically switch to another line in VRAM. By storing various zoom steps in the VRAM pages you may be able to get a decent zooming vertically.

Indeed, horizontally will need pure calculational and/or VDP power. But I don't have the impression Edge of Disgrace zooms images at 50 fps on the C64 either (except for the sprites, which is 'cheating' )

Very cool demo indeed. <thumbs up/>

It's not just the vram access speed. Which would still be slightly lower than the blitter with a plain z80. It's what you can gain with inexpensive random access to the vram. Even having a separate read/write pointer can help some tasks out a LOT. Take for instance the bitbuster decoder for vram. It's very slow compared to the ram version due to the high cost of doing vram copies. But the g9k version with a separate read/write pointer is almost as quick.

Which parts of the demo do you think are undoable on MSX? IMO the disco dancefloor, plasmas, 3D revolvers, the slow image zooming and all 'simple' effects should be perfectly possible on MSX2. Fullscreen coloured sprites are out of the question, moving sprites behind foreground and zooming sprites is difficult but not impossible on MSX and the 3D moving objects - MSX is probably slower at that but it has been done before.

I'm not volunteering to remake it for MSX myself but I guess most of it can be done making full use of MSX2 features.