Fractal mountain outline using midpoint subdivision

mountain1d.py

import sys, random
from pyglet.gl import *

window = pyglet.window.Window(500,500)

seed = int(random.uniform(0,10000))
if len(sys.argv) > 1:
	seed = int(sys.argv[1])

def generateHeights(level):
    random.seed(seed)
    numPoints = 2**level + 1
    p = [0] * numPoints
    displacement = 100.0
    for l in range(level-1, -1, -1):
        step = 2**l
        for i in range(step, numPoints, step*2):
            p[i] = (p[i-step] + p[i+step])/2.0 + random.gauss(0.0, displacement)
        displacement /= 2.1
    return p

def generateMountain(level):
    heights = generateHeights(level)
    verts = []
    x = 0
    for y in heights:
        verts += [x, y + 200]
        x = x + 500.0/(len(heights)-1)
    return pyglet.graphics.vertex_list(len(heights), ('v2f', verts))

level = 0
vlist = generateMountain(level)

@window.event
def on_draw():
    global vlist
    glClear(GL_COLOR_BUFFER_BIT)
    vlist.draw(GL_LINE_STRIP)


@window.event
def on_key_press(key, modifiers):
    global level, vlist
    if key == pyglet.window.key.PLUS or key == pyglet.window.key.EQUAL:
        level += 1
        vlist = generateMountain(level)
    elif key == pyglet.window.key.MINUS and level > 0:
        level -= 1
        vlist = generateMountain(level)

pyglet.app.run()