Subject: Re: [stella] Unending VDEL hell From: "Eckhard Stolberg" <Eckhard_Stolberg@xxxxxx> Date: Mon, 29 Apr 2002 16:59:51 +0200 |
> I tried to take Thomas' suggestions from a while back and implement them as > literally as I could, and no matter what I do I either get 1-scanline > precision with the 2nd car down a line or both cars offset by 2 scanlines > or on the same scanline but animating in 2-scanline jumps. If you are trying to get double scanline display precision with single scanline positioning precision, then the trick is to change the state of the VDEL registers and the vertical object position depending on whether the objects have to be displayed in the first or the second scanline of you double scanline block. You have to create a two line kernel. In the first line you write to GRP0, and in the second line you write to GRP1. The writes have to happen during the horizontal blank. If there are areas where the players can't be positioned, then the writes can happen in these areas too. Now lets look at two double lines with different VDEL states. The displayed value in each line would be like this: player0 display player1 display write VDELP0-on VDELP0-off VDELP1-on VDELP1-off line1: P0=$01 $01 line2: P1=$01 $01 $01 $01 line3: P0=$02 $01 $02 $01 $01 line4: P1=$02 $02 $02 $01 $02 So the rules that you can derive from that are: P0 in line 1: VDELP0=off, start writing in this double line P0 in line 2: VDELP0=on, start writing in this double line P1 in line 1: VDELP1=on, start writing in previous double line P1 in line 2: VDELP1=off, start writing in this double line Ciao, Eckhard Stolberg ---------------------------------------------------------------------------------------------- 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] Unending VDEL hell, Glenn Saunders | Thread | Re: [stella] Unending VDEL hell, Thomas Jentzsch |
Re: [stella] Cosmic Ark disassemble, Thomas Jentzsch | Date | Re: [stella] Unending VDEL hell, Manuel Polik |
Month |