Subject: R: R: [stella] RESCUE.BIN, it's a little tougher now From: "Piero Cavina" <p.cavina@xxxxxxxxxxxxx> Date: Fri, 22 Aug 1997 22:21:41 +0200 |
> Da: Greg Troutman <mor@xxxxxxx> > The harder part was making them move at different speeds, but > it makes it much nicer I think. Sure... how did you do it? In my game, each enemy has a 16-bit register for the horizontal position. Only the high-order part is used to position the sprite. At the beginning, I had also a 16-bit, two's complement increment value for each enemy; then, to save RAM, I've chosen a 3-bit index to a table of increments. Since 1 bit is for direction, there can be up to 2^2=4 different speeds for the enemies. That seems a decent compromise and I could save a lot of memory. Please note that to have the same speeds both in PAL and NTSC it would be enough to use increments that are multiples of 5 in NTSC, then multiplying them by 6/5 for the PAL version. Hope I've been clear... Ciao, P. -- Archives updated once/day at http://www.biglist.com/lists/stella/archives/ Unsubscribing and other info at http://www.biglist.com/lists/stella/stella.html
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