Subject: Re: [stella] New project - Need help From: Manuel Polik <cybergoth@xxxxxxxx> Date: Wed, 28 Mar 2001 12:01:29 +0200 |
Hi Maximilian! > I'm not sure I understand these terms. I think 2 Sprites should be enough, > but I don't know if it should be the best choice. Any suggestions are > welcome. Ok, since the line you're talking about is a sprite, it get's very easy. Instead of the Sprite Data you suggested here: > Sprite_Top > db %11111111 > db %00000000 > db %00000000 > db %00000000 > db %00000000 > db %00000000 > db %00000000 > db %00000000 > Sprite_Botton > db %00000000 > db %00000000 > db %00000000 > db %00000000 > db %00000000 > db %00000000 > db %00000000 > db %11111111 All you'd have to do is positioning Player 0 horizontally and then writing $FF to GRP0 on the desired line in your kernel. The code in the kernel would come down to: LDX #$00 ; assume wrong line CPY desiredLine ; Are we on the desired line? BNE WrongLine ; N: We'e on the wrong line DEX ; Y: Put $FF into X WrongLine STX GRP0 ; Write SpriteData This is assuming that Y holds the current Line you're drawing and desiredLine is a RAM variable, where you'd hold the scanline where your Spriteline shall become visible. Now, to move the line up or down, you'd read the Joystick and increment/decrement desiredLine according to its reading. Ok, this was in short the way for someone who knows the basic principles how the VCS works. Since I fear that you're still too much a beginner to understand what I said (that's judging from your two mails, I really don't want to be rude here, just helpfull), I'd suggest, that you go to Nick Bensemas homepage, where you'll find some documents helping you with the first basic steps and teaching you the main principles how the VCS works. The URL of the docs section is: http://www.io.com/~nickb/atari/docs.html There, I'd especially recommend reading the 'Stella Programmer's Manual' and Nicks very own 'How To Draw A Playfield' sample source. Start toying around with that. Later then, go back to this mail and continue with your program :-) Greetings, Manuel - Archives (includes files) at http://www.biglist.com/lists/stella/archives/ Unsub & more at http://www.biglist.com/lists/stella/
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