compute a Mandelbrot set and draw it using OpenGL points

glmandelbrot.py

import sys, random
from pyglet.gl import *

width = 400
height = 400

singlebuffered = pyglet.gl.Config(double_buffer=False)
window = pyglet.window.Window(width,height,config=singlebuffered)


maxIter = 32

def mandelbrot(c, maxIter):
    iter = 0
    z = c
    while iter < maxIter:
        z = z*z + c
        if abs(z) > 2: return iter
        iter = iter + 1
    return -1


def GreyscaleColormap():
	map = []
	for i in range(0,256):
		map.append((i,i,i))
	return map


def BlueGreenRedColormap():
	map = []
	for i in range(0,85):
		map.append((0, 0, int(i/85.0 * 255)))
	for i in range(0,85):
		map.append((0, int(i/85.0 * 255), 0))
	for i in range(0,86):
		map.append((int(i/85.0 * 255), 0, 0))
	return map

colormap = BlueGreenRedColormap()

center = (-0.75, 0.25)
size = 1.0


@window.event
def on_draw():
    glClear(GL_COLOR_BUFFER_BIT)
    glMatrixMode(GL_PROJECTION)
    glLoadIdentity()
    gluOrtho2D(-0.5, width+0.5, -0.5, height+0.5)
    glMatrixMode(GL_MODELVIEW)
    
    for i in range(0,width):
        x = (i/(width-1.0)*size) - size/2.0 + center[0]
        glBegin(GL_POINTS)
        for j in range(0,height):
            y = (j/(height-1.0)*size) - size/2.0 + center[1]
            m = mandelbrot(x+y*1j, maxIter)
            if m == -1:
                glColor3ub(255,255,255)
            else:
                m = m * 255 / maxIter
                glColor3ub(colormap[m][0], colormap[m][1], colormap[m][2])
            glVertex2i(i,j)
        glEnd()
        glFlush()


@window.event
def on_key_press(key, modifiers):
    global size, maxIter
    if key == pyglet.window.key.EQUAL or key == pyglet.window.key.PLUS:
        size = size / 2.0
    elif key == pyglet.window.key.MINUS:
        size = size * 2.0
    elif key == pyglet.window.key.A:
        maxIter += 16
    elif key == pyglet.window.key.S:
        maxIter -= 16

pyglet.app.run()