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Dither City by Taquart
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popularity : 47% |
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alltime top: #36755 |
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added on the 2021-03-14 14:07:04 by 0xF  |
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comments
great
Cool noisy dither pattern
quite nice, but the hellmood's version is more elegant
Quote:
This prod is 32 bytes of code plus a mandatory 6-byte header, which was excluded by compo rules. This makes the whole file 38 bytes long, hence I selected two categories on pouet.net.
Originally the prod was smaller, but not that fast.
Please write more technical details behind this entrie. How it is practically done?
It's a linear gradient from black to 75% white, using hardware-accelerated pseudo-random dithering.
It's very fast for 320x192 on a 40-year-old hardware because:
1. The 8-bit pseudo-random number is retrieved from the POKEY chip's RANDOM register which gets updated every cycle. The pixel value is computed by comparing the Y coordinate with the value of RANDOM: pixel_is_white=(RANDOM<=Y).
2. It writes directly to screen RAM. The OS "plot" would be slower by several orders of magnitude.
The source is on GitHub.
This technique can be used for any 256-level grayscale effect in hires. It takes one instruction (compare with RANDOM) to convert the grayscale level in one of the three CPU registers to the dithered pixel in the C flag.
It's very fast for 320x192 on a 40-year-old hardware because:
1. The 8-bit pseudo-random number is retrieved from the POKEY chip's RANDOM register which gets updated every cycle. The pixel value is computed by comparing the Y coordinate with the value of RANDOM: pixel_is_white=(RANDOM<=Y).
2. It writes directly to screen RAM. The OS "plot" would be slower by several orders of magnitude.
The source is on GitHub.
This technique can be used for any 256-level grayscale effect in hires. It takes one instruction (compare with RANDOM) to convert the grayscale level in one of the three CPU registers to the dithered pixel in the C flag.
Very interesting...
submit changes
if this prod is a fake, some info is false or the download link is broken,
do not post about it in the comments, it will get lost.
instead, click here !
Originally the prod was smaller, but not that fast.