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A spaceship.

Entry posted by atari2600land January 23, 2018

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So I've been playing with channel F programming today, seeing if I can get an object to move without a trail behind it. I don't know why, but it seems as though apparently it doesn't clean up previous bitmaps after drawing them? This discovery was used in Kevin Vs. Tomatoes. So I made a second object trailing behind it the same color as the background. This technique works pretty good. So I made this program of a spaceship travelling left across the screen in a dusk sky with the ground below. It's like Space Jockey for the Atari 2600. If I plan to make a game out of this, that's what I'm basing it on.

But for now, I'm just goofing around to see if I can get an object moving without traces of it behind. I'm still wondering how many objects the Channel F can have onscreen at once. I'm guessing quite a lot due to Alien Invasion.

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carlsson 26,549

Posted January 24, 2018

If everything is one plane of foreground characters on a solid background (or perhaps technically everything is background but at different colours), I would suppose the number of "objects" equals the pixel resolution divided by the size of each object. Someone mentioned that the graphics memory is write only which means you need to keep track of each object elsewhere through variables in RAM which seems like a challenging task once the number of objects are many. I don't know if it has enough memory to keep a duplicate of the screen memory for you to peek into, if the hardware graphics are not readable.