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tecM0
Registered: Jan 2002
Posts: 40 |
4x4 FLI
hi,
i never used that (overused?) 4x4_effect by myself.
i think itb looks really cool with dithered chars.
the "fractal_vector_part" in MATHEMATICA uses
something like that, or?
how does this 4x4_FLI_FX work? as i sayd..i never
used FLI...and really hates timing.
but it could be a very short routine within a kind
of loop.
if i set a IRQ to the 1st line of the FLI...set the
screen and then set the IRQ to the next line of FLI
(4 pixellines down?) ....do this work? and how?
i never can find a demo_source around the net and
all demos i have "monitored" use speedcode(generators).
does a routine like the one i explained exist and does
it work like this at all?
thanx for help,
tecM0
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Cybernator
Registered: Jun 2002
Posts: 154 |
Quote: Floyd-Steinberg thingy? What's that?
A dithering algorithm based on error diffusion. |
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Graham
Account closed
Registered: Dec 2002
Posts: 990 |
floyd steinberg on 2x4 pixels... yeah sure |
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tecM0
Registered: Jan 2002
Posts: 40 |
hello graham,
have seen this:
"...and I suddenly came up with this very simple idea how to do 4x4 without losing 60% of the rastertime..."
on
http://c64.rulez.org/onslaught/interviews/int25.php
can you explain this simple idea to a unsuspecting /me?
thanx a lot,
tecM0
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Cybernator
Registered: Jun 2002
Posts: 154 |
Quote: floyd steinberg on 2x4 pixels... yeah sure
I've just created an environment map, and dithered it using Photoshop. Then exctracted the blocks, and I ended up with a dithered charset. It did work. :) IMO, pattern dithering produced better result than error diffusion, in this case.
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tecM0
Registered: Jan 2002
Posts: 40 |
no OXY_tutorial?
btw...i still also dont know how this
screendisorting worx... .. .
=(
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Graham
Account closed
Registered: Dec 2002
Posts: 990 |
the idea was to have a small irq every 8 rasterlines. nowadays this might sound pretty simple but back then it was the first custom resolution running in fullscreen size without munching up all the rastertime. before that any custom gfx mode based on fli ate up all cycles in the display area. |
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Cybernator
Registered: Jun 2002
Posts: 154 |
The bumpmapper works! :-D It wasn't difficult as I first thought. However, it is slow even if it's using unrolled code.
Yeah, I need to use chained interrupts. But I can also have a separate IRQ every 4th rasterline, instead of every 8th, right? There comes the stable raster issue again. The double IRQ method would be inefficient for this case, wouldn't it? I'm studing the auxilary timer method now, but wouldn't different CIAs give different results? I'll probably need to wait an additional cycle on newer CIAs, and that takes CIA type recognition routine and such crap. Any easier method?
Only the lines where badline should be given at cycle 14 are a problem. The others are easier as I've got cycles 1-11.
--
OT: I found this about Deus Ex Machina in the interview above:
"Another guy wondered why I did the interference part because 'it's easy to do' "
The multiplexer was cerainly not simple. It took me two weeks of coding to replicate Graham's interferences! (Maybe I could have done it faster if there wasn't for BOFH :))
Of course I had all the guidelines from the original like where sprites are positioned, how layers are organized, etc. And the most important: As I saw it was possible, I was encouraged to go to the end. If I've never seen it, I might drop it saying: "This is impossible!"
The most problematic is the presence of two sprite layers. What if the rasters get too close? It would flicker. Then what if there's a badline? (Have in mind that there's also a char layer!)
In my experience, the bumpmapper was much easier than the interferences. And the complexity of an effect is not always important. The effect looks awesome, no matter what.
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Cybernator
Registered: Jun 2002
Posts: 154 |
I've been thinking... I don't need an IRQ every 4th rasterline. :) I can generate a badline at cycle 14, then immediately set $D012 four rasterlines below. RC is supposed to reset so there's no problem. |
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Cybernator
Registered: Jun 2002
Posts: 154 |
I really don't get it! I made the chained IRQs using the auxilary timer method, and it works perfectly on both CIA types. Both CIAs generate IRQ at the same cycle. And if I try the proggy Yago told me about, it is really able to detect the CIA. Are there special cases when this occures? It's cool that I don't need a CIA recognition routine, but I have to know about this stuff. Maybe I should check the detection routine. :)
Now let's see if this will speed-up the bumpmapper. |
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tecM0
Registered: Jan 2002
Posts: 40 |
i have checked the routines from
ftp://ftp.elysium.pl/gnu-generation/Brush/raster.zip
(not reachable anymore...user/pass...:( )
and it does the same graham explained. dont know if it is
the same way he made it but its a lot of rastertime left
on screen!
thx!
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