More comments about Flipdraw and why it's nice:
1. You do not need to set a pointer every time you move your sprite.
Actually, you only need to set it once.
2. Graphics data need not be aligned carefully - no more worries about
wrapping page boundaries for the whole vertical range of the sprite. As
long as the graphics data itself doesn't cross a page boundary, it will
work.
3. If you aren't animating your sprites, I think you could use absolute
indexed addressing for your sprite data and save a cycle and two bytes of
RAM.
>FWIW, the Alpha 0.1 and 0.2 bB kernel uses this too, mostly because of the
>pointer setup thing. However, I will probably use a kernel rewritten with
>skip/switchdraw to get more on the screen, but I'm not looking forward to
>the pointer setup stuff. Actually, I haven't figured out how to setup the
>pointers at all yet...
>
> >Hi there!
> >
> >How about...
> >
> > LDA #SPRITEHEIGHT
> > DCP spriteOffset
> > BCC FlipDraw
> > LDY spriteOffset
> > LDA (spritePtr),Y
> >Continue
> > STA GRP0
> >
> >That's 2/3 cycles more than skip/switchdraw, but it neither requires a
> >line counter (save lotsa cycles here!) nor occupies a register.
> >
> >I'm currently working on a 4LK with 2LK sprites, and this seems to be by
> >far the most elegant way to do that :-)
> >
> >Also instead of the nightmarrish sprite/pointer setup for skip/switchdraw
> >it only requires a setup as simple as:
> >
> > LDA spriteY
> > STA spriteOffset
> > SET_POINTER spritePtr, spritedata
> >
> >Greetings,
> >Manuel
> >Archives (includes files) at
>http://www.biglist.com/lists/stella/archives/
> >Unsub & more at http://stella.biglist.com
> >
>
>
>Archives (includes files) at http://www.biglist.com/lists/stella/archives/
>Unsub & more at http://stella.biglist.com
>
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