My first MSX demo!

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Por Hrothgar

Champion (479)

imagem de Hrothgar

29-12-2008, 09:51

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).


Enlighted (6935)

imagem de ARTRAG

29-12-2008, 10:55

Edge of Disgrace has some X/Y zooming effects that msx -at that framerate- cannot do.
Years agoo I tried some zooming algorithms based on vdp copies (screen5),
but the max speed you can have (1/4 of screen areas) is about 10 frames/sec.

Por Hrothgar

Champion (479)

imagem de Hrothgar

29-12-2008, 11:59

@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' Tongue )

Por Maggoo

Paragon (1217)

imagem de Maggoo

29-12-2008, 17:40

@ Hrothgar/Artrag. Zoom effect is fairly easy to do even in screen 5 with precalc patterns for X zoom and using the vertical scroll register for Y zooming, I think I must have used this trick once or twice in the past in full screen and 50FPS. There is not much to it really, of course you are limited by how many precalc patterns you can store in memory for the X zoom. It probably would give a much better result using this trick with screen 2/4 to store bigger patterns.
It's probably a similar trick used in C64 demos as they are using repeating patterns all over the screen.

Regarding the "dance floor" effect, it reminds me of games like trailblazer / Squeek. I never quite figured out how those are done but I guess the effect is not that different ?

Por AuroraMSX

Paragon (1902)

imagem de AuroraMSX

29-12-2008, 19:23

Very cool demo indeed. <thumbs up/>

Por PingPong

Enlighted (4140)

imagem de PingPong

29-12-2008, 21:44

The lack of direct vram access is indeed a shortcoming. Much more apparent in v9938 though. .

The main problem on v9938 and follow up is the bigger vram in this situation. Even if you can have a memory mapped access.

Moving 24kb is too large for a 3.5 mhz z80.
If the vdp blitter could be 5 times faster, even with a port based access one could get interesting effects.

Por Edwin

Paragon (1182)

imagem de Edwin

30-12-2008, 00:28

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.

Por Vampier

Prophet (2413)

imagem de Vampier

30-12-2008, 05:45

I just saw Edge of Disgrace... the c64 dances circles arround the MSX when it comes to video speed.... damn.

Por Hrothgar

Champion (479)

imagem de Hrothgar

30-12-2008, 10:25

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 Tongue but I guess most of it can be done making full use of MSX2 features.

Por Arkhan

Champion (259)

imagem de Arkhan

30-12-2008, 22:59

makes me proud to have jumped the C64 boat and swam to the MSX Island.......

This is awesome.

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