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xIII
Registered: Nov 2008
Posts: 210 |
vertical raster split
After a lot of trial and error, looking into other code and even more frustrating hours I finally think I understand how to do vertical rastersplits without flickering. Hooray hooray... but ... now I got this strange fenomena that in the middle of my rasterbars this 3 chars appear, on every line.
Anyone an idea what causes these characters to appear ?
this is a short extract of the code:
ldy #88
!loop: lda raster1,y // 4
sta $d020 // 4
lda raster2,y // 4
sta $d021 // 4
lda raster1,y // 4
sta $d021 // 4
lda raster2,y // 4
sta $d021 // 4
lda raster1,y // 4
sta $d021 // 4
lda raster2,y // 4
sta $d021 // 4
lda $d012 // 4
and #%00000111 // 2
sta $d011 // 4
dey // 2
bpl !loop- // 3 |
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Chesoner
Account closed
Registered: Apr 2013
Posts: 28 |
It has to do with $d011.
Change these lines :
.var rl1 = $32
.var rl2 = $32+8*12
in
.var rl1 = $38
.var rl2 = $38+8*12
The "chars" are then shifted to the right. |
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xIII
Registered: Nov 2008
Posts: 210 |
@Chesoner: true, but they are still visible, so that's not a solution.
if I change $32 to $10 (or something else in the upper border) the chars are gone but also the splits are gone :p |
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Mace
Registered: May 2002
Posts: 1799 |
Isn't this know as the FLI bug? |
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Chesoner
Account closed
Registered: Apr 2013
Posts: 28 |
If i put it on $36 then i see no bug in winvice, only rasters. |
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xIII
Registered: Nov 2008
Posts: 210 |
@chesoner: true again :) thanx for checking !
But does anyone have a good explenation for the appearing chars ? |
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Chesoner
Account closed
Registered: Apr 2013
Posts: 28 |
Quote: @chesoner: true again :) thanx for checking !
But does anyone have a good explenation for the appearing chars ?
What Mace said. |
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Pantaloon
Registered: Aug 2003
Posts: 124 |
and there is a bug in the code (will cause problems later on :))
irq2: sta $02
sta $03
sta $04 |
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Oswald
Registered: Apr 2002
Posts: 5017 |
with fld (tear open screen pushing it down) you can achieve more splits, but gfx is not possible. add 01 to d012 + and #07 ora #$10 + tweak horizontal timing until good. |
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chatGPZ
Registered: Dec 2001
Posts: 11108 |
Quote:But does anyone have a good explenation for the appearing chars ?
it happens when you trigger the badline condition in a way that the 3 pre-DMA cycles are within the visible screen area. in those 3 cycles the VIC fetches the videoram data from "floating" bus (which will usually result in $ff). (i think the vic article explained in it more detail) |
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xIII
Registered: Nov 2008
Posts: 210 |
@pantaloon: I already corrected that ;)
@oswald: will try that, thx
@Groepaz: thank you ! |
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