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Monte Carlos
Registered: Jun 2004
Posts: 351 |
Three pixel period pattern on upper/lower border
Any idea, how to create a hires pattern like this:
110110110110110110110110110110110110...
on the upper/lower border over the full width. Every trick allowed.
Btw: $3fff trick does not work, because then the pattern has a period of eight instead of three. Sprites cover only a width of 192 pixels!
Thank you Monte!
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JackAsser
Registered: Jun 2002
Posts: 1990 |
Possible with C128 or REU if "every" trick is allowed. :D |
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Monte Carlos
Registered: Jun 2004
Posts: 351 |
Reu is really cool, but only C64 allowed.
Thanks Monte
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Skate
Registered: Jul 2003
Posts: 491 |
I didn't think on it so long but first trick come to my mind allows 248 pixels instead of 192. leave 8 pixel gaps between unexpanded sprites. you need to change $3fff like a split every four cycles which shoudn't be so hard. all you need is 3 different $3fff combinations. so the code should look like this.
lda #%11011011
ldx #%01101101
ldy #%10110110
sta $3fff
stx $3fff
sty $3fff
sta $3fff
stx $3fff
sty $3fff
sta $3fff
this should fill the 8 pixel gaps between sprites which extends the pattern to 248 pixels but still you will need 72 pixels I know...
edit: actually with one more stx $3fff it is possible to have 256 pixels wide pattern like that. why did I miss that? :)
edit2: if you start placing sprites with a 8 pixel gap already and put the correct value to $3fff on the right border, you will have 264 pixels of correct pattern. 56 to go. :)
edit3: I just noticed that sprites wouldn't cover $3fff pattern completely. so, this method may not work at all. |
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Oswald
Registered: Apr 2002
Posts: 5023 |
put $3fff on zp, then it can be done :D |
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Monte Carlos
Registered: Jun 2004
Posts: 351 |
@Skate:
$d021 = White
Background is visible, when both $3fff and sprite bits are 0
x = resulting Pixel in white
%11011011%11011011%11011011%11011011 $3fff = Black
%10010010%01001001%00100100 Sprite = White
%00x00x00%x0xx0xx0%0xx0xx0x%00x00x00
Good idea, but it doesn't seem to work for the two bytes in the middle.
@Oswald: How can i put $3fff into zeropage??? Do you mean
lda zp, sta $3fff = 5 cycles ?? Or is there a way to place
the ghostbyte below $0100 which i do not know?
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Street Tuff
Registered: Feb 2002
Posts: 88 |
putting $3fff to zp is only possible on c64 dtv. |
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Mace
Registered: May 2002
Posts: 1799 |
You are now asking to think about a solution you have already chosen: a pattern in the border.
There might be another solution for your problem.
What exactly is the reason you want this pattern in the first place?
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Monte Carlos
Registered: Jun 2004
Posts: 351 |
The pattern mentioned above is part of a two color hires bitmap i want to extend into the upper and lower border.
I was experimenting with sprites over ghostbyte pattern and
didn't find a way to create the pixel combination 1101101100..., because of the three pixel period. I thought, maybe someone comes to another result and finds away to create this pixel combination.
Important is, that the pattern should not be made of double, but single pixels.
Monte
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Skate
Registered: Jul 2003
Posts: 491 |
@Monte Carlos: I hate to use that trick but I think it's your last chance.
"It's impossible to do something like that. Even Crossbow cannot do it."
;) |
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Jetboy
Registered: Jul 2006
Posts: 221 |
Interesting puzzle! I need to go to the tolet so i mihght come up with idea when i get back... |
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