geodelines.py

# Gregory Kehne

# This program draws randomly generated lines that squiggle but maintain a
# roughly uniform distance from one another. This is inspired by the growth
# lines that appear in the cross-sections of geodes, and by the work of
# artist Sol LeWitt, specifically "Wall Drawing 797".

import math
import random
from PIL import Image, ImageDraw

# this is the squiggle generator!
# step<=gap
# i is the index of the line
# j is the 'height' index within the line
# lines[i][j]=(x-coord, y-coord)


def squiggles(height, width, step, gap):
	# array to contain all relevant points
	lines = []
	# temp list to store the previous line
	line = []
	# how far over the lines start
	seed = 500

	# generate squiggly lines
	for i in range(0, width, gap):
		if i == 0:  # generate the original line
			rprev = 0.0
			rprevprev = 0.0
			rprevprevprev = 0.0
			for j in range(0, height / step):
				randomness = random.uniform(-4, 4) + random.uniform(-3, 3) +random.uniform(-2, 2)
				randomness += .5 * rprev + 0.25 * rprevprev + 0.125 * rprevprevprev
				line.append((seed + randomness, j * step))
				rprevprevprev = rprevprev
				rprevprev = rprev
				rprev = randomness
				seed = seed + randomness
		else:  # generate derivative lines
			newline = []
			for j in range(0, height / step):
				poss = []  # x-value candidates to choose from
				for d in range(- (gap / step) + 1, gap / step):
					if j + d >= 0 and j + d < height / step:  # in y-range
						poss.append(line[j + d][0] + math.sqrt(gap ** 2 - (d * step) ** 2))
				newline.append((max(poss) + random.uniform(-0.5, 0.5), j * step))
			line = newline
		lines.append(line)
	return(lines)


# this is the main method.
# parameters are dimensions of screen, step within line, gap between lines,
# output file name
def main (height, width, step, gap, name):
	# generate squiggles
	lines = squiggles(height, width, step, gap)
	# new image created
	im = Image.new('RGBA', (height, width), (255, 255, 255, 0))
	draw = ImageDraw.Draw(im)
	# draw the lines
	# i iterates horizontally across lines
	for i in range(len(lines)):
		drift = i / len(lines)  # make function that drifts between colors.
		color = (random.randint(int(0 + drift * (130)), int(60 + drift * 100)),
					random.randint(int(100 - (drift * (100 - 32))),
					int(190 - drift * (190 - 32))), random.randint(210, 220), 0)
		# width for line
		w = random.randint(3, 5)

		# draw all the individual segments. Here j steps down the vertical axis
		for j in range(len(lines[i]) - 1):
			draw.line((lines[i][j][0], lines[i][j][1], lines[i][j + 1][0],
						lines[i][j + 1][1]), fill=color, width=w)
	# saves the generated Image
	im.save(name + ".jpg")


# Default behavior: create an image 2000x2000 named geode_test.jpg with 
# lines that take 4-pixel steps and sit 30 pixels apart.
if __name__ == '__main__':
	main(2000, 2000, 4, 30, "geode_test")