Add experimental 2D noise

lib/cs_noise.py

@@ -0,0 +1,21 @@
+#!/usr/bin/env python
+
+import numpy as np
+import scipy.ndimage
+
+
+def noise2d(width, height, smooth=1.8, filter_mode='wrap', falloff=0.02,
+            power=3):
+    rng = np.random.default_rng()
+    x = np.zeros((1, 1))  # Zero mean
+    iterations = int(np.ceil(np.log(max(width, height)) / np.log(power)))
+    falloff *= smooth
+    contribution = 1
+    for i in range(iterations):
+        upscaled = np.zeros((x.shape[0] * power, x.shape[1] * power))
+        upscaled[power // 2::power, power // 2::power] = x
+        x = scipy.ndimage.gaussian_filter(upscaled, smooth, mode=filter_mode)
+        x += rng.normal(scale=contribution, size=x.shape)
+        contribution *= falloff
+
+    return x[:width, :height]