next »

[Sik]

The problem with PC is that it lacks proper timing mechanisms for doing raster effects so it's pretty unstable in practice. The best you can do is use the timers to trigger an IRQ after certain amount of time (resetting the timer every frame to prevent drifting) and even then whether you hit hblank or not is hit and miss.

See for example this:

The left portion of the scanline where the palette change happens is unstable, because that's where the CPU gets the interrupt and does the palette change. It isn't always during the blanking period =/ At least it's kind of hidden by the water moving up and down for starters.

[happymonster]

Ah I see.. The Atari had a chip for Display Line Interrupts so you could always change on the right scan line.

[Sik]

To be fair there's the fact that many programmers probably didn't even know you could do that, so it isn't hard to understand why they didn't try. The timing issue is at worst a flickering scanline (as long as you reset the timer every frame), so as long as you account for that it isn't really bad.

Do any CGA games besides California Games do raster effects, though? I knew about California Games already (good to know it wasn't just done in the title screen), but I can't think of any other game doing it.

[standardcombo]

That makes sense but imagine even if you knew about it, what would the art pipeline look like? You'd probably need some new tools. We have similar problems nowadays. Here's a cool effect, you could make a game around it... or make a game with an established framework/style and lower engine costs.

[Sik]

Honestly in this case you could probably just make the artwork in grayscale and be careful to not cross the relevant lines. I think it's more a case of programmers not being given enough time to learn more than the basics of the hardware... (also that many features didn't work properly in clone hardware, e.g. custom EGA palettes didn't work in many EGA clones, so they were avoided usually)

[Blambo]

Apparently with some scanline palette-swapping hackery CGA 4-colour-mode could do this:


And with some composite video hackery:

more like BORE colors.

but actually that's super cool and clever