Subject: Re: [stella] subpixel joustpong From: "Andrew Davie" <atari2600@xxxxxxxxxxxxx> Date: Tue, 3 Feb 2004 21:36:57 +1100 |
> If you want to play with the physics numbers yourself, > I made a javascript tool to convert decimal numbers into > binary, since figuring the two's complement stuff was getting > to be a serious pain, you can see and use that at > http://kisrael.com/viewblog.cgi?date=2004.02.03 > (oops, I just noticed that Window's calculator now lets > you do some kind of specification of how many bytes... > well, it still seems fiddley to use. and the javascript thing was kind > of fun to slap togehter.) Nice, but un-necessary. Let the assembler do the work.... lda #<NUMBER sta var lda #>NUMBER sta var+1 Now set NUMBER to whatever you want. The two-byte variable "var" will hold the low byte (in var) and the high byte (in var+1). But what about negative numbers in two's complement form? The assembler automatically does it! NUMBER = -2984 lda #<NUMBER sta var lda #>NUMBER sta var+1 voila! I'm not even going to check it -- trust me. Oh, yea of little faith! By the way, to negate numbers (single byte)... clc lda var eor #$FF adc #1 sta var or, for two-byte negation, easiest is to subtract the number from 0 sec lda #0 sbc var sta var lda #0 sbc var+1 sta var+1 Subpixel joustpong is looking much better, but i think the gravity should be roughly 4x as strong, and the flapping should be about 1/4 of the power. So you really have to flap to keep your position, and going up is major flap time. One other thing... had a brief look at your code. Instead of.. NUMBER = #8 it's more standard to just go NUMBER = 8 Cheers A ---------------------------------------------------------------------------------------------- Archives (includes files) at http://www.biglist.com/lists/stella/archives/ Unsub & more at http://www.biglist.com/lists/stella/
Current Thread |
---|
|
<- Previous | Index | Next -> |
---|---|---|
[stella] subpixel joustpong, KirkIsrael | Thread | Re: [stella] subpixel joustpong, Andrew Davie |
Re: [stella] Seawolf: Day Fifteen, Glenn Saunders | Date | Re: [stella] subpixel joustpong, Andrew Davie |
Month |