Blitter Smudge bit

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Frank
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Blitter Smudge bit

Postby Frank » Tue Oct 26, 2004 10:25 pm

Hi folks.

Does anyone have any info on what the smudge bit on the blitter can be used for? I've heard it can be used as an indirect addressing mode for 1 to 4 pixel scaling but I can't see an application for it.

I think it takes the least significant 4 bits of each shifted word and the selects the half tone line for a logical AND with the source. I can't think of what I'd use that for. The Atari blitrer manual is a bit vague on this point.

I would love to see an explanation for it if anyone has a tutorial or some good docs :)

Thanks in advance,

Frank
People of the world can be classified as 10 groups. Those that understand binary and those that don't ;)

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tobe
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Postby tobe » Wed Oct 27, 2004 2:20 am

yes, you right, but you can also just copy the halftone line.
also, the result can be modified by the 3 masks.

about applications, i don't know, i never took time to think about it :)
step 1: introduce bug, step 2: fix bug, step 3: goto step 1.

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earx
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Postby earx » Mon Nov 22, 2004 9:01 am

my intelligence division reports that it was meant by atari for stuff like adding some dither patterns.

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tobe
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Postby tobe » Mon Nov 22, 2004 2:08 pm

You mean dithering ram can be used to add dithering ? :)
Or smudge mode is another way to add dithering ?
step 1: introduce bug, step 2: fix bug, step 3: goto step 1.

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earx
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Postby earx » Mon Nov 22, 2004 7:26 pm

the latter i think... actually, i heard this from paranoid. he is really good with the blitter. he didn't use it for dithering himself though but for some other effects =)


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