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8585 Commits

Author SHA1 Message Date
Kartik K. Agaram 2777479a94 experiment: scaling pixels to 255 levels 
This is strictly worse than before, both with barbara.pgm and more
subtly with t.pgm.
 2021-07-13 05:19:00 -07:00
Kartik K. Agaram 23330d06c7 . 
Undo commit 70a03be0d0 and reinline the helper extracted there.

I have a better sense now of the primitives to reuse between greyscale
and color dithering.

https://merveilles.town/@akkartik/106571585137582228
 2021-07-12 22:53:27 -07:00
Kartik K. Agaram a4f36d60ef more precise error-diffusion 
The Barbara test image has been looking right since commit 430dd67cb2.
However, t.pgm has not. This doesn't fix it, but does seem like an
improvement.

The remaining error seems to be unrelated to rounding. Adding 8 more
bits of precision has no effect.
 2021-07-12 00:59:36 -07:00
Kartik K. Agaram 4e5e887e01 . 2021-07-12 00:16:02 -07:00
Kartik K. Agaram b646d24b06 . 2021-07-11 15:43:58 -07:00
Kartik K. Agaram 9c4a381770 . 2021-07-11 15:35:55 -07:00
Kartik K. Agaram c76ac49f8f forget HSL conversion for now, stick to RGB 
It looks like seeking the nearest neighbor in HSL space leads to more
saturated colors.
 2021-07-11 15:31:15 -07:00
Kartik K. Agaram e8b8584796 . 
Inline a helper.
 2021-07-11 11:42:10 -07:00
Kartik K. Agaram 70a03be0d0 . 
Extract a helper.
 2021-07-11 09:25:24 -07:00
Kartik K. Agaram 7e21abe0c9 . 
Inline an unnecessary block.
 2021-07-11 09:18:47 -07:00
Kartik K. Agaram 5234ba60f5 . 2021-07-11 09:16:46 -07:00
Kartik K. Agaram 598fe88ebb . 2021-07-11 03:47:15 -07:00
Kartik K. Agaram 430dd67cb2 dither 256-level greyscale to 8-level greyscale 2021-07-11 03:14:17 -07:00
Kartik K. Agaram eb6cee6022 . 2021-07-10 21:15:51 -07:00
Kartik K. Agaram e1dc0e8250 . 2021-07-10 20:37:21 -07:00
Kartik K. Agaram a97a7cb8c4 . 2021-07-10 20:10:30 -07:00
Kartik K. Agaram 80023c3e54 . 2021-07-10 20:03:16 -07:00
Kartik K. Agaram b28a31315e increase precision for dithering computations 
Now we get a perfect checkerboard pattern.
 2021-07-10 19:56:32 -07:00
Kartik K. Agaram 3420f10f18 . 
https://merveilles.town/@akkartik/106559551043772522
 2021-07-10 19:47:32 -07:00
Kartik K. Agaram e377991a9e . 
https://merveilles.town/@akkartik/106557664535993377
 2021-07-10 11:18:47 -07:00
Kartik K. Agaram 5f8a8c11a2 dithering greyscale using black/white 
Starting to look right.
 2021-07-10 10:51:39 -07:00
Kartik K. Agaram 2a0f6cbb6f reorder a few functions 2021-07-08 17:08:34 -07:00
Kartik K. Agaram 76f1fdc83e . 2021-07-08 16:57:07 -07:00
Kartik K. Agaram 0539b961a0 scaling ppm images 2021-07-08 16:53:06 -07:00
Kartik K. Agaram b8488c5223 scaling pgm images 2021-07-08 16:43:34 -07:00
Kartik K. Agaram f07ebb9e5e . 2021-07-08 16:33:49 -07:00
Kartik K. Agaram b049cc1320 . 2021-07-08 16:23:48 -07:00
Kartik K. Agaram 13ef6b6202 . 2021-07-08 16:20:17 -07:00
Kartik K. Agaram 3ee70401e3 . 2021-07-08 16:12:27 -07:00
Kartik K. Agaram 019fb0babc scaling pbm images 2021-07-08 11:00:51 -07:00
Kartik K. Agaram b628bbd686 . 2021-07-08 09:26:55 -07:00
Kartik K. Agaram afda7d59c0 better ppm colors 
I had some logic to make hue distance cylindrical, but it wasn't right.
 2021-07-08 01:13:38 -07:00
Kartik K. Agaram 0f29e61238 better greyscale 2021-07-08 00:26:58 -07:00
Kartik K. Agaram 9c70f7c643 . 2021-07-08 00:21:01 -07:00
Kartik K. Agaram 359f55d893 . 2021-07-08 00:13:12 -07:00
Kartik K. Agaram d1482a9e89 ppm colors are weird, though 2021-07-08 00:12:31 -07:00
Kartik K. Agaram 91af9ccf2c ppm support 
Typo in commit fe3cbcd77: it only rendered pbm/pgm.
 2021-07-07 19:43:56 -07:00
Kartik K. Agaram d73c84e299 instructions for Universal Ctags 
Thanks Sumeet Agarwal for raising this issue.
 2021-07-07 19:34:54 -07:00
Kartik K. Agaram d78a45340c . 2021-07-07 19:24:12 -07:00
Kartik K. Agaram fe3cbcd778 render ppm/pgm 
Looks pretty bad compressing 256 shades of grey to 8.
 2021-07-07 09:57:18 -07:00
Kartik K. Agaram a9353ea327 load ppm/pgm/ppm on demand 2021-07-07 08:35:17 -07:00
Kartik K. Agaram ef73cb78f1 initial image rendering 
Supports just some ASCII formats: https://en.wikipedia.org/wiki/Netpbm

Colors are messed up. That's next.
 2021-07-07 07:13:16 -07:00
Kartik K. Agaram 2d3fe4e940 . 2021-07-06 21:35:22 -07:00
Kartik K. Agaram c31c02f0d1 . 2021-07-06 08:39:46 -07:00
Kartik K. Agaram d84d17d6f5 nearest h/s/l color by a euclidean metric 2021-07-06 07:01:14 -07:00
Kartik K. Agaram cbf22e7ab2 primitives for double-buffering 
I thought I needed these for this bouncing-ball demo:

  def (bounce screen)
    with (w (width screen)
          h (height screen)
          cx 16
          cy 16
          dx 12
          dy 19)
      while 1
        clear screen
        ring screen cx cy 16 3 5
        cx += dx
        cy += dy
        when (or (cx > w) (cx < 0))
          set dx 0-dx
        when (or (cy > h) (cy < 0))
          set dy 0-dy
        for _ 0 (< _ 100) ++_         # delay

No matter how I adjusted the delay I couldn't get rid of the jitter. So
I built a double-buffered version:

    (bounce2 . [def (bounce2 screen)
  with (w (width screen)
        h (height screen)
        cx 16
        cy 16
        dx 12
        dy 19
        screen2 (new_screen (columns screen)
                            (lines screen)))
      while 1
        clear screen2
        ring screen2 cx cy 16 3 5
        cx += dx
        cy += dy
        when (or (cx > w) (cx < 0))
          set dx 0-dx
        when (or (cy > h) (cy < 0))
          set dy 0-dy
        blit screen2 screen
        for _ 0 (< _ 100) ++_])       # delay

But it didn't make a difference! Turns out nothing will help you when
successive frames are too far apart. This is the correct tweak to
`bounce`:

  -       dx 12
  -       dy 19)
  +       dx 1
  +       dy (/ 19 12))

Still, we'll keep double-buffering around for the future.
 2021-07-05 23:18:30 -07:00
Kartik K. Agaram 468b0d979f shell: fix clear on screens 
Broken since commit c95648c96 on Jul 3.

Unclear what test to write for this. Should clear-stream check for NULL?
Should apply-clear?
 2021-07-05 22:06:37 -07:00
Kartik K. Agaram 5d614af955 expose Mu implementation of 'bezier' 
Still no support for acute-angled control points.
 2021-07-05 18:31:07 -07:00
Kartik K. Agaram 493aabf79a replace 'circle' with Mu implementation 2021-07-05 18:21:02 -07:00
Kartik K. Agaram c7bedaf49b replace 'vline' with Mu implementation 2021-07-05 18:12:07 -07:00