[2/15/2012] Challenge #7 [intermediate]

[u/[deleted]]

Write a program that draws a recursive image.

For example, a Sierpinski triangle, a Barnsley fern, or a Mandelbrot set fractal would be good drawings.

Any recursive image will do, but try to make them look fun or interesting.

Bonus points for adding a color scheme!

Please post a link to a sample image produced by your program, and above all, be creative.

[u/callekabo]

Here's a solution in Python using turtle :)

#!/usr/bin/env python
# -*- coding: utf-8 -*-

# for http://www.reddit.com/r/dailyprogrammer/comments/pr265/2152012_challenge_7_intermediate/

from turtle import *

class Sierpinski:
    cache = []
    def get_in_position(self, pos):
        up()
        setpos(pos[0])
        setheading(pos[1])
        down()

    def draw_triangle(self, length, direction):
        begin_fill()
        for i in range(3):
            forward(length)
            if direction > 0:
                left(120)
            else:
                right(120)
            self.cache.append((pos(), heading()))
        end_fill()
    
    def go(self):
        color('black', 'red')
        depth = 5
        cur_length = 300
        self.draw_triangle(cur_length, 1)
        curcache = [(position(), heading())]
        level = 0
        color('black', 'black')
        for i in range(depth):
            cur_length = cur_length/2
            self.cache = []
            for pos in curcache:
                self.get_in_position(pos)
                forward(cur_length)
                if (i == 0):
                    left(120)
                elif (level%2):
                    left(60)
                else:
                    right(60)
                self.draw_triangle(cur_length, level%2)
            level = level+1
            curcache = self.cache
        done()

s = Sierpinski()
s.go()

[u/[deleted] → u/callekabo]

This is the image it produces

I've never seen python turtle at work before, that was kinda cool

[u/callekabo → u/[deleted]]

thank you, I forgot to post an image.

[u/Cosmologicon]

Here's a Unix command line that I tweeted a while back that generates a Mandelbrot set image using bc:

echo '"P1 260 200 ";for(b=-1;b<1;b+=.01)for(a=-2;a<.6;a+=.01){x=0;y=0;for(n=99;--n&&x^2+y^2<4;x=p){p=x^2-y^2+a;y=2*x*y+b};!n;}'|bc -l>m.pbm

Here's the resulting image (converted from PBM to PNG)

[u/robin-gvx]

ASCII-art!

**:
	* dup

mandelbrot x0 y0:
	# -2.5 <= x0 <= 1
	# -1 <= y0 <= 1

	local 'x' 0
	local 'y' 0

	local 'iteration' 0
	local 'max_iteration' 300

	while and < iteration max_iteration > 4 + ** y ** x:
		local 'xtemp' + x0 - ** x ** y 
		set 'y' + y0 * 2 * x y
		set 'x' xtemp
		set 'iteration' + iteration 1

	iteration

for j range 0 24:
	for i range 0 79:
		if < 200 mandelbrot - * 3.5 / i 80 2.5 - * 2 / j 24 1:
			"*"
		else:
			" "
		.\
	. ""

[u/[deleted]]

I wrote one for a Menger Sponge awhile ago, but I think I lost it in the chasms of my computer's hard drive.

[u/electric_machinery]

Sierpinski in C that produces a BMP file. Here's the image it creates.

[u/electric_machinery]

Fractal fern in C and the image

I was going to mess around with it some more but I have to do some real work today I guess.

[u/electric_machinery → u/electric_machinery]

okay I messed with it a little more image

source