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Dr.j
Registered: Feb 2003
Posts: 277 |
help with delay table making tech tech
Hey there again. i want to do a little tech tech effect.
i think i manage Ok with the charsets (took me some time to
arrange right the chars) and i have $d018 and $d016 tables
the main problem is now.. Delay tables . i use this routine
what is the best technique to do "Fine tune" the delays?
i will gladly hear your ideas to do fast delay tables.
i first tried to replace $d016+$d018 with $d021 but it didnt help me much. please don't send me to "missing cycles" article..hehe . btw i don't have any problems to make "rasters" delays but here its different.
ldx #$00
loop:
lda d018tab,x
sta $d018
lda d016,x
sta $d016
ldy delaytab,x
dey
bne *-1
inx
cpx #$2f
bne loop
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Oswald
Registered: Apr 2002
Posts: 5094 |
why mess up x with d012 compare?
edit: oh I see now. |
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Flavioweb
Registered: Nov 2011
Posts: 463 |
Quote: @flavioweb: I can imagine that as being not entierly glitch free... ;)
Maybe it don't work, i have not tested, but what you see wrong in this code? Do you think there is a timing problem, or you see some other error? |
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chatGPZ
Registered: Dec 2001
Posts: 11386 |
you should try it out :) use d020 and d021 for testing, you'll see what the problem is then :) |
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Flavioweb
Registered: Nov 2011
Posts: 463 |
Quote: you should try it out :) use d020 and d021 for testing, you'll see what the problem is then :)
I can't test now, but i know isn't stable. But i also think we have sufficient time to set registers before raster reach visible area so for a tech-tech effect may work.
May be wrong... of course =} |
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Radiant
Registered: Sep 2004
Posts: 639 |
Flavioweb: http://thedarkside.ath.cx/commodore/vic/vic_article_3.4.htm#3.5. |
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algorithm
Registered: May 2002
Posts: 705 |
How are you able to change d018 at any vertical position? You would need to force a badline unless the sinus wave is calculated in a way taking into account when d018 can be switched. |
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tlr
Registered: Sep 2003
Posts: 1790 |
@algorithm: the usual way is to switch the charsets not the screen memory. |
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algorithm
Registered: May 2002
Posts: 705 |
I was thinking of the other method involving screen mem instead of gfx data and adjusting d018 with a long sinus wave. This elimates the issue of using forced badlines |
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chatGPZ
Registered: Dec 2001
Posts: 11386 |
are you sure what tech tech is? how would a specialised sine table help at all? |
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Radiant
Registered: Sep 2004
Posts: 639 |
Groepaz: Well, if you could construct your table so that xscroll would cross character boundraries only on even 8th lines it would work... Never heard of it being used though, and it seems pretty limiting compared to the standard shifted charset method. |
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