Subject: Re: [stella] Confused newbie... From: "Thomas Jentzsch" <tjentzsch@xxxxxx> Date: Wed, 6 Oct 2004 09:23:49 +0200 |
Kevin Lipe wrote: > What would be the best way to position sprites and such in a kernel > for the game concept I was talking about in the above thread? Attached > is the code I've got right now, which just makes a really pretty > playfield and nothing else. I suppose you want to reposition your sprites *inside* the kernel, right? The most simple code for this would look like this: ldx index ; the current sprite index lda posLst,x ; a list containing all horizontal positions (0..159) sta WSYNC ---------------- sec ; 2 .wait: sbc #15 ; 2 bcs .wait ; 2/3 eor #$07 ; 2 asl ; 2 asl ; 2 asl ; 2 asl ; 2 sta HMP0 ; 3 sta.w RESP0 ; 4 @23+n*5 sta WSYNC ; 3 ---------------- sta HMOVE This is however a general solution, which allows positioning sprite 0 across the whole screen and uses one whole scanline For your kernel you may need something more specialized, e.g. - objects cannot move accross the whole screen, so you can free some cycles for other kernel stuff - you don't have that much free time inside your kernel, then you should calculate the fine and coarse positioning values outside the kernel. This saves a few cycles and allows additional tricks (e.g. two different codes for positioning objects on the left and right, giving you more free cycles for other stuff) - ... So this can get quite complicated later, but for a start I suppose using something like the code above. Have fun! Thomas _______________________________________________________ Thomas Jentzsch | *** Every bit is sacred ! *** tjentzsch at web dot de | ____________________________________________________ Aufnehmen, abschicken, nah sein - So einfach ist WEB.DE Video-Mail: http://freemail.web.de/?mc=021200
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