Re: Genesis color counts, myths shattered?

Scott H wrote:
Hmm, so the water in Sonic 1 isn't using a varient of this shadow technique? It's odd that two different palettes can be displayed on screen while Gif Movie Gear still only detects about 45 colors. I mean, the level design might simply be limited to half the colors per palette, but it isn't noticably so. Aquatic Ruins in Sonic 2 shows up as 75 colors though, that's the first time I've seen a Genesis pic go over 61 colors. That at least demonstrates the changed color palette. If that could be used in a game like Sonic 2 (especially with the amount of apparent parallax in that level), then it's more fair to say that the Genesis color limitation is more of a limit per sprite or background (like it was on the TG16), rather than an absolute on screen limitation. In other words, that it's only limited in the sense that color gradients on a single object would be less than that of the Snes. Which brings the question of how many Snes games didn't use the mode with 16 color sprites, and how they overcame the background limitation of that higher sprite color mode.

Well, you have a maximum of 16 colors per pallet line, and four pallet lines for a total of 64 colors as the hardware "limit", so that's why you hear people saying that the Genesis can display 64 colors "max". The Genesis can choose from 512 base colors (8 bits per color component, and 8*8*8=512). So yeah, the only real limits are 16 colors per tile, which can be any of four pallet lines, so you can only have 64 "base" colors at any one time. The techniques to increase the colors are just basically changing those colors mid-frame and using shadow/highlight to get extra colors.

Theoretically, you could have a "screen mode" on the Genesis similar to that of the Amiga's "Dynamic Hires" mode, which changed all 16 pallet entries every scanline - the Genesis can't quite do this, but you could change 8 of the colors each line, so you could change the first 8 colors on even scanlines and the second 8 on odd scanlines. You could probably also use other graphics on-screen at the same time (sprites or the other scroll layer), but they'd have to stay away from the pallet that you're changing every line.


It's also possible to change the backdrop at any arbitrary point on the screen, even right smack dab in the middle of a scanline. Many games use this for simple gradients in the background (a good example is Shadow of the Beast). I've written proof-of-concept code that did 18 "raster splits" (where the backdrop was changed mid-line), but due to various issues the splits jittered. I could probably do more if I used CPU registers instead of memory to store the values, but I digress.

There are definitely ways of making a machine display more than the "official" color limit - this really applies to quite a few systems (for example, the Commodore 64 can display 16 hardware colors, and at a 160x200 resolution is can display 3 colors plus background in a 4x8 character bitmap (two bits per pixel). However, very ingenious coders have blown that "limit" completely away - through techniques such as interlacing and sprite overlay, I've seen images with upwards of 90 apparent colors at an apparent resolution of 320x200.

I'd be very interested to see things like this in action. I can't really picture what it would look like.

Well, I lost my work on the raster splits in a hard drive semi-failure (the drive still spins up, but it's bad enough where I can't boot from it, but I think I could salvage some of the data). Also, just in case I wasn't quite so clear, the 90-color thing I mention was of course on the C64. You can see a lot of the C64 stuff at http://www.demodungeon.com, it can be quite amazing.
.

Relevant Pages

  • Re: LPD3DXSPRITE and display of a .tga with alpha channel ??
    ... > I am display a sprite with the texture loaded from a .tga file. ... > 32 bit file with alpha channel and a resolution of 700x525. ...
    (microsoft.public.win32.programmer.directx.graphics)
  • LPD3DXSPRITE and display of a .tga with alpha channel ??
    ... I am display a sprite with the texture loaded from a .tga file. ... 32 bit file with alpha channel and a resolution of 700x525. ...
    (microsoft.public.win32.programmer.directx.graphics)
  • RE: Display 2D image using textured quad
    ... you do need to call Beginand Endon each sprite object (within ... Display 2D image using textured quad ... >"Terry" wrote: ...
    (microsoft.public.win32.programmer.directx.graphics)
  • Re: ID3DXSprite::Draw screen image doesnt match texture???
    ... If you're using D3DX for loading the texture, ... function that stretched the dimensions to powers of two. ... > I am displaying a sprite from a .tga file thats 32 bit with alpha channel ... My laptop display runs 1400x1050. ...
    (microsoft.public.win32.programmer.directx.graphics)
  • Re: Genesis/Sega CD colour counts....
    ... on-screen at once, in hardware, without programmers resorting to ... Master System could display, which was either 52 or 32 at once. ... Master System hardware came out in 1984 or 1985 in Japan as the Sega ... Genesis' arcade ancestor, the System 16 board, from around ~1986 could ...
    (rec.games.video.sega)