Subject: Re: [stella] Sprites - AAAAARGH! From: Thomas Jentzsch <tjentzsch@xxxxxx> Date: Fri, 30 Jan 2004 21:33:53 +0100 |
KirkIsrael wrote: > This code, I assume, WSYNCs, and then waits just long enough > so that when the RESP0 is called the object is repositioned > at just the right point? Almost, see below. > Does this code assume that when it's called as a subroutine > Accumulator is set to the position, and X is 0 or 1 based on > which player you're trying to move, or what? Yup! And you can also position both missiles and the ball with that. > In short, what > are the preconditions for this routine, and/or does it involve > something w/ the stack? a contains x-position (0..159) x contains object index (0..4) And there is an important *post*condition. After all objects have been *coarse* positioned you have to do this once: sta WSYNC sta HMOVE > (Actually, I tend to be more concerned about time than ROM space (or > reusability) so I tend not to use subrotuines much at all...) A few, not too nested subroutines aren't that bad. And if you store all x-positions in consecutive RAM locations, you can make this a loop (without any JSR) too. Have fun! Thomas _______________________________________________________ Thomas Jentzsch | *** Every bit is sacred ! *** tjentzsch at web dot de | ---------------------------------------------------------------------------------------------- Archives (includes files) at http://www.biglist.com/lists/stella/archives/ Unsub & more at http://www.biglist.com/lists/stella/
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