Add demo without mayavi

Author: enesdemirag

exercises/materials/perlin-noise/demo2.py

@@ -0,0 +1,15 @@
+from opensimplex import OpenSimplex
+import matplotlib.pyplot as plt
+
+def heightmap(n):
+    noise = OpenSimplex()
+    z = [[0 for x in range(n)] for y in range(n)]
+    for i in range(n):
+        for j in range(n):
+            z[i][j] = (noise.noise2d(((i + 1) / 10), ((j + 1) / 10)) + 1) * 10
+    return z
+
+z = heightmap(100)
+
+map = plt.imshow(z, cmap='terrain')
+plt.show()