[spam][crazy][random] Rotary Encoder: Slightly More Productive Goal

[Undiscussed Horrific Abuse, One Victim of Many]

y'know there must be code for this somewhere already. but this makes a
quick analog image.

>
commit 7e23db09ca066d41c7e1227d5444c2d5f3482151 (HEAD -> main, origin/main,
origin/HEAD)
Author: xloem <0xloem at gmail.com>
Date:   Sun Mar 27 23:13:15 2022 -0400

    implement quickly

diff --git a/gen_encoder_wheel/__main__.py b/gen_encoder_wheel/__main__.py
index f1bd4f6..608eb43 100644
--- a/gen_encoder_wheel/__main__.py
+++ b/gen_encoder_wheel/__main__.py
@@ -3,6 +3,12 @@ from imageio import v3 as iio
 import numpy as np
 import click

+# i used to have an idea for very precise position detection.
+# i do not remember what that idea was.
+
+def angle2intensity(distance, angle):
+    return angle / np.pi / 2
+
 @click.command()
 @click.option('--size', default=4096, help='Height of wheel.')
 @click.option('--ratio', default=1.0, help='Aspect ratio of wheel. width =
ratio * size')
@@ -10,8 +16,13 @@ import click
 @click.option('--output', help='Output filename.')
 def generate(size, ratio, dpi, output):
     height = size * dpi
-    width = height * ratio
-    img =
np.random.randint(0,0xffff,size=(int(width+.5),height,3),dtype=np.uint16)
+    fwidth = height * ratio
+    width = int(fwidth+.5)
+    x = np.tile(np.arange(width) / (fwidth - 1) * 2 - 1, (height, 1))
+    y = np.tile((np.arange(height) / (height - 1) * 2 - 1)[:, None], width)
+    dists = np.sqrt(x * x + y * y)
+    angs = np.arctan2(x, y)
+    img = (angle2intensity(dists, angs) * 0xffff +
np.random.random((width, height))).astype(np.uint16)
     return write(output, img)

 def write(fn, ndimg):
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