Elena's code blog - Figuring Stuff Out

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It's taken me a few days to understand how sprites are supposed to work. I've got a single sprite working in the office game, but it still needs serious cleanup so I'm not going to show it (despite saying I would). I was finding it impossible to do everything on one scanline, so I ended up doubling them up to get more cycles, which worked out pretty well except for the lower sprite resolution.

 

Anyway. I was playing around with colors and I'd like to do something simulating motion with color cycling. I've seen games like Solaris, Beamrider, Moonsweeper, Robot Tank, Star Strike, Death Star Battle, and several others do it but the way they do it doesn't look all that realistic. The colors really need to achieve a smoother gradient by not cycling colors with such large deltas (resulting in highly contrasting colors). Lots of games do that easily for runs of 8 to 16 pixels, but I'm referring to the full screen height. The scanlines need to be "dithered" with closely matching hues along the vertical axis. All the games I've seen do that appeared to be static backgrounds, not dynamic.

 

As for cycling colors horizontally, I haven't seen any 2600 games that do it. If there are, I bet they're slow. I have a game concept I'd like to look into if the horizontal cycling is at all feasible. I know doing that is no where near as trivial as it is doing it vertically, but I think it might be worthwhile to fool around with it. If I can't figure it out, I could still reorient the game vertically and do it that way, so there's always that option.

 

One last thing, I was playing around with the timer for driving my color changes. As far as I understand, the INTIM counter is managed by the RIOT chip and decrements in parallel with 6502 instructions. That would mean it could be used to perform repeating decrements with 2 (or 5) fewer cycles for each time, assuming the A,X,Y registers are used for other stuff. There's got to be ways to exploit that.

 

So, that pretty much sums up what I've been doing. I do have 3 bin files. They're not much to see, just me trying to figure out sprites. 2 of those files use the timer. As for the office game, I need to focus on straightening out the timing and refactoring the code.

 

Attached File(s)

 

pointer.bin ( 4K )

Number of downloads: 1

rainbow_horizon.bin ( 4K )

Number of downloads: 0

rainbow_noise.bin ( 4K )

Number of downloads: 0

 

 

 

 

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