lsca.uni.py

@@ -0,0 +1,84 @@
+#!/usr/bin/env python3
+
+import sys
+import numpy as np
+
+
+def lament(*args, **kwargs):
+    return print(*args, file=sys.stderr, **kwargs)
+
+
+def colorize(x):
+    return x * 17 % 256
+
+
+def render(row):
+    grays = colorize(row)
+    if scale > 1:
+        grays = np.repeat(grays, scale)
+    line = " ".join(str(x) for x in grays)
+    for y in range(scale):
+        print(line)
+
+
+def limit(row):  # in-place
+    row[row < 0] = 0
+    row[row > 15] = 15
+    return row
+
+
+def initialize():
+    row = np.zeros(width, int)
+    prev, here = 0, 0
+    for i in range(width):
+        if np.random.randint(0, 8) == 0:
+            here = np.random.randint(16)
+        row[i] = here
+        prev = here
+    limit(row)
+    return row
+
+
+name, args = sys.argv[0], sys.argv[1:]
+
+if len(args) == 0:
+    rule_lut = None
+elif len(args) == 16:
+    rule_lut = [int(x.strip(",")) for x in args]
+else:
+    lament(f"usage: {name}")
+    lament(f"usage: {name} {{rules 1 through 16}}")
+    sys.exit(1)
+
+scale = 3
+width, height = 960 // scale, 960 // scale
+
+if rule_lut is None:
+    rule_lut = np.random.randint(-2, 2 + 1, size=(4, 4))
+    lament(" ".join(f"{x:+2}" for x in rule_lut.flat))
+else:
+    rule_lut = np.array(rule_lut).reshape(4, 4)
+
+print("P2")  # magic code for an ascii Portable GrayMap (PGM) file
+print(width * scale, height * scale)
+print(255)  # maximum color value
+
+row = initialize()
+
+for i in range(height):
+    # left, center, right:
+    L = np.roll(row, 1)
+    C = row.copy()
+    R = np.roll(row, -1)
+
+    diffusion = (L + C + C + R + 2) // 4
+
+    # v = [0,1,2,3,1,0,3,2,2,3,0,1,3,2,1,0][V]
+    y = (L ^ (L >> 2)) % 4
+    x = (R ^ (R >> 2)) % 4
+
+    delta = rule_lut[y, x]
+    row = diffusion + delta
+
+    limit(row)
+    render(row)