Subject: Re: [stella] Crackers' Easy Playfield Graphics Code From: Nick S Bensema <nickb@xxxxxxxxxxxx> Date: Sat, 8 Mar 1997 15:34:00 -0700 (MST) |
This code looks effective, but the following technique will make it difficult to add players, unless you want your players to only be positionable every 8 scanlines or so, as Centipede and both versions of Frogger do. > LDY #$08 ;how many scanlines is each block? > LDX #$17 ;number of blocks of data. LDY * LDX = 192! > >load LDA playf0,X ;load in the data for playfield 1 > STA PF0 > LDA playf1,X ;load in the data for playfield 2 > STA PF1 > LDA playf2,X ;load in the data for playfield 3 > STA PF2 > >grfx STA WSYNC ;draw the scanline > DEY ;decrease the block number > BEQ block ;if it's zero it's time for a new block > JMP grfx ;if not then repeat the previous scanline et cetera. Instead of spitting out eight WSYNCs, you could use that time to position or draw a sprite. Perhaps there isn't time to do both if you want the full eight scanlines. Crackers has sort of taken care of a concept I was going to write about: multi-scanline scanning loops. His takes 8 scanlines to do not really that much, but it would have been incredibly useful if, say, he were writing a Pac-Man game and he used the 4th and 5th scanlines to place and remove a row of dots from the playfield. -- To unsubscribe, send the word UNSUBSCRIBE in the body of a message to stella-request@xxxxxxxxxxx
Current Thread |
---|
|
<- Previous | Index | Next -> |
---|---|---|
[stella] Crackers' Easy Playfield G, crackers | Thread | [stella] Now I've got it!!!! Sorry , crackers |
Re: [stella] Final thought...., Nick S Bensema | Date | Re: [stella] NTSC - PAL porting gui, Nick S Bensema |
Month |