Python: Turtle graphics and rsTurtle module

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I have always found it useful, in addition to creating a custom class for canvas drawing, to create a set of turtle graphics commands.

For simplicity, there are no routines provided for viewport, scale, transform, rotate, or pushing or popping transformation matrices.

The rsTurtle module contains the turtle class that subclasses the canvas class in the rsCanvas module.

The various methods of the turtle class are now presented and discussed.

The initializer calls the super class canvas and then sets some instance variables.

def __init__(self, stub1, width1=640, height1=480, back1="FFFFFF"):
	super().__init__(stub1,width1,height1,back1)
	penDown1 = 0
	angle1 = 0
	polyList1 = []

The pen is down when penDown1 is 1, else it is 0.
The angle of the turtle is angle1 in degrees.
The list of coordinates to be drawn is in the list polyList1.

def up(self):
	if penDown1 != 0:
		if len(polyList1) > 1:
			draw()
		penDown1 = 0

def down(self):
	if penDown1 != 1:
		penDown1 = 1
		polyList1 = []
	polyList1.append((x1, y1))

def turnto(self, degrees1):
	angle1 = float(degrees1)
	while angle1 >= 360.0:
		angle1 -= 360.0
	while angle1 < 0.0:
		angle1 += 360.0

def turn(self, degrees1):
	turnto(angle1 - float(degrees1))

def move(self, distance1):
	distance1 = float(distance1)
	dx1 = distance1 * math.cos(math.radians(angle1))
	dy1 = distance1 * math.sin(math.radians(angle1))
	x1 += dx1
	y1 += dy1
	if penDown1 == 1:
		polyList1.append((x1, y1))

The draw method draws the current points, if needed.

def draw(self):
	if len(polyList1) > 1:
		draw1.line(polyList1,fill=color(edge1),width=thick1)
	polyList1 = []

Here is a code module in Python [module rsTurtle in rsTurtle.py].

# module rsTurtle.py
import rsCanvas
import math
class turtle(rsCanvas.canvas):
	def __init__(self, stub1, width1=640, height1=480, back1="FFFFFF"):
		super().__init__(stub1,width1,height1,back1)
		penDown1 = 0
		angle1 = 0
		polyList1 = []
	def up(self):
		if penDown1 != 0:
			if len(polyList1) > 1:
				draw()
			penDown1 = 0
	def down(self):
		if penDown1 != 1:
			penDown1 = 1
			polyList1 = []
		polyList1.append((x1, y1))
	def turnto(self, degrees1):
		angle1 = float(degrees1)
		while angle1 >= 360.0:
			angle1 -= 360.0
		while angle1 < 0.0:
			angle1 += 360.0
	def turn(self, degrees1):
		turnto(angle1 - float(degrees1))
	def move(self, distance1):
		distance1 = float(distance1)
		dx1 = distance1 * math.cos(math.radians(angle1))
		dy1 = distance1 * math.sin(math.radians(angle1))
		x1 += dx1
		y1 += dy1
		if penDown1 == 1:
			polyList1.append((x1, y1))
	def draw(self):
		if len(polyList1) > 1:
			draw1.line(polyList1,fill=color(edge1),width=thick1)
		polyList1 = []
print("(module rsTurtle imported)")

Here is a fractal routine to draw a Koch coastline.

def fractal1(dx1, n1):
	if n1 == 0:
		turtle1.move(dx1)
	else:
		n2 = n1 - 1
		dx2 = dx1 / 3.0
		fractal1(dx2,n2)
		turtle1.turn(60.0)
		fractal1(dx2,n2)
		turtle1.turn(-120.0)
		fractal1(dx2,n2)
		turtle1.turn(60.0)
		fractal1(dx2,n2)

Here is the code to draw 6 levels of Koch coastline.

for n1 in range(0,5+1):
	turtle1 = rsTurtle.turtle(stub1,width1,height1,back1)
	turtle1.thick1 = 2
	turtle1.edge1 = "006600"
	turtle1.moveto(x1,y1)
	turtle1.turnto(0.0)
	turtle1.down()
	fractal1(dx1,n1)
	print("n={0:d} line segments: {1:d}".format(n1,len(turtle1.polyList1)))
	turtle1.draw()
	turtle1.save()

Here is the setup code.

width1 = 480
height1 = 240
back1 = "FFFFFF"
x1 = 0.2 * width1
x2 = width1- x1
dx1 = x2 - x1
y1 = 0.5 * height1

The stub is set in the main code.

Here is the Python code [#12]

import rsTurtle
def fractal1(dx1, n1):
	if n1 == 0:
		turtle1.move(dx1)
	else:
		n2 = n1 - 1
		dx2 = dx1 / 3.0
		fractal1(dx2,n2)
		turtle1.turn(60.0)
		fractal1(dx2,n2)
		turtle1.turn(-120.0)
		fractal1(dx2,n2)
		turtle1.turn(60.0)
		fractal1(dx2,n2)
stub1 = "draw22-12"
width1 = 480
height1 = 240
back1 = "FFFFFF"
x1 = 0.2 * width1
x2 = width1- x1
dx1 = x2 - x1
y1 = 0.5 * height1
for n1 in range(0,5+1):
	turtle1 = rsTurtle.turtle(stub1,width1,height1,back1)
	turtle1.thick1 = 2
	turtle1.edge1 = "006600"
	turtle1.moveto(x1,y1)
	turtle1.turnto(0.0)
	turtle1.down()
	fractal1(dx1,n1)
	print("n={0:d} line segments: {1:d}".format(n1,len(turtle1.polyList1)))
	turtle1.draw()
	turtle1.save()