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SIDWAVE
Account closed
Registered: Apr 2002
Posts: 2238 |
Timing rasters with sprites over
I am gone stuck in trying to get some rasters be stable under some sprites.
There are 8 sprites, not moving.
Here's what I have:
color .byte 0,6,14,1,14,6,0,14
timer .byte 4,3,5,5,10,4,5,1
ldy #4
_swap dey
bne _swap
ldx #0
_doit lda color,x
sta d020
sta d021
ldy timer,x
_wrap dey
bne _wrap
inx
cpx #8
bne _doit
I've never learned about the badlines, is it
something with that, if i wanna time these rasters ?
Thanks
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SIDWAVE
Account closed
Registered: Apr 2002
Posts: 2238 |
Ok, with the help of a nice guy, I got stable rasters under sprites.
But there is a problem.
I get some garbage gfx, it looks like D020 color appearing in D021 area, or $3fff issues.
I cleared $3fff, but it had no effect..
The color of this garbage gfx is set nowhere by me.
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HCL
Registered: Feb 2003
Posts: 716 |
If you didn't put the garbage gfx, it wouldn't be there >:). Sounds like perhaps you're doing..
lda color
sta $d020
sta $d021
..a bit too late in your "loop". It's not possible to get a 100% bugfree raster with random sprites on top. You will always see some bugs in the outermost borders. However, the d021-area does not need to get buggy. Just check the demos from 1988-89.. full of stuff like that :).
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SIDWAVE
Account closed
Registered: Apr 2002
Posts: 2238 |
The buggy gfx changes when i change the timing.
It has color lightgreen, and my rasters are blue (0,6,14,1,14,6,0). The sprites are red/white.
It looks a lot like that D020/3fff trick you can do in the border to make 9 sprites.
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MRT
Account closed
Registered: Sep 2005
Posts: 149 |
Are you blocking badlines by altering $d011?
Because it sounds to me like you're filling the first 3 bits of $d011 with the first 3 bits of $d012. And thereby triggering a badline, showing the FLI bug on your screen...
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SIDWAVE
Account closed
Registered: Apr 2002
Posts: 2238 |
I do:
lda $d012
and #%00000111
ora #%00011000
sta $d011
lda rastercolors,x
sta $d020
sta $d021
nop
...
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MRT
Account closed
Registered: Sep 2005
Posts: 149 |
Well, there's your problem.
You're generating a bad-line when you set your raster colors.
Try this:
(this code takes 2 cc more!)
lda $d012
sbc #$03 ;no need for sec
and #%00000111
ora #%00011000
sta $d011
If you can't handle the 2 extra clockcycles then try the following timing trick:
(using example values below)
on rasterline 40, do:
lda $d012
then go to next rasterline in the following two lines of code
and #%00000111
ora #%00011000
on rasterline 41, do:
sta $d012
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MRT
Account closed
Registered: Sep 2005
Posts: 149 |
Or even easier...
Try this:
lda $d012
and #%00000111
eor #%00011100
sta $d011
This takes exactly the same amount of cycles as your own routine, but makes sure that the first 3 bits of $d012 and $d011 aren't the same! (and therefore don't create a badline) |
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Hein
Registered: Apr 2004
Posts: 933 |
or try a $d011 table, filled with goody goodlines.
lda nobad,x
sta $d011
lda color,x
sta $d020
sta $d021
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Oswald
Registered: Apr 2002
Posts: 5017 |
or drink a cofee with intensity. |
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