Dragon Curve

Dragon Curve.py

from scene import *
from math import atan, cos, sin, sqrt, log

ratio = 0.5

def bump(start, end):
	x1, y1 = start
	x2, y2 = end
	length = sqrt((x2-x1)**2 + (y2-y1)**2)
	midx = (x2 + x1) / 2
	midy = (y2 + y1) / 2
	normx = (y1 - y2) * ratio
	normy = (x2 - x1) * ratio
	x = midx + normx
	y = midy + normy
	return x, y

def iteration(pts, *tpts):
	pts = tuple(pts) + tpts
	iterated = []
	for i, pt in enumerate(pts[:-1]):
		iterated.append(pt)
		nxt = pts[i+1]
		new = bump(pt, nxt) if i % 2 else bump(nxt, pt)
		iterated.append(new)
	iterated.append(pts[-1])
	return iterated

def dragon(pts, lim=3):
	for i in range(lim):
		pts = iteration(pts)
	return pts

class MyScene (Scene):
	def setup(self):
		# This will be called before the first frame is drawn.
		background(1, 1, 1)
		stroke(0, 0, 0)
		stroke_weight(1)
		x1, y1 = 300, 400
		x2, y2 = 800, 400
		line(x1, y1, x2, y2)
		self.pts = ((x1, y1), (x2, y2))
		self.count = 0
	
	def draw(self):
		# This will be called for every frame (typically 60 times per second).
		pass
	
	def touch_began(self, touch):
		background(1, 1, 1)
		self.pts = iteration(self.pts)
		for i, pt in enumerate(self.pts[:-1]):
			x1, y1 = pt
			x2, y2 = self.pts[i+1]
			line(x1, y1, x2, y2)
	
	def touch_moved(self, touch):
		pass

	def touch_ended(self, touch):
		pass

run(MyScene())