Subject: Re: [stella] Resetting algorithm From: Erik Mooney <emooney@xxxxxxxxxxxxxxxx> Date: Fri, 14 Apr 2000 20:01:37 -0400 |
> So, I was watching Stella at 20, wolume 2 the other day (which, I might >add, is a quality video, and a pleasure to have in my collection), and one >of the guys was talking about his algorithm that he invented for Air-Sea >Battle, such that someone could pass in a number of pixels for which an >object was to be placed horizontally, and it placed the object >appropriately, using a reset, and an hmove. > I didn't have time to copy down the code (which was written on a piece of >paper in the video). Does anyone know it offhand, and how it works? I >just assume that it generates a certain number of NOPs for the resetting, >and that the HMOVE number can be calculated as well. Hm? That wouldn't really make sense, unless he was talking about a compile-time tool. You can't generate NOPs at runtime on the 2600 (well, you _can_ put them in RAM and run them, but that'd be pretty inefficient..) Most object-positioning routines run a do-nothing loop for the right amount of time and then hit the sprite-reset register, then use the HMOVE registers for fine-tuning the position because the do-nothing loop only has a resolution of five cycles (15 pixels). I just use a lookup table in my programs - put in a pixel number and get back the number of times to go around the loop and the number to write to HMP0. -- Archives (includes files) at http://www.biglist.com/lists/stella/archives/ Unsub & more at http://www.biglist.com/lists/stella/
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