import turtle, math

DRAW_FRACTAL = 1  # Set to 1 through 11 and run the program.

turtle.tracer(5000, 0) # Increase the first argument to speed up the drawing.
turtle.hideturtle()

def drawFilledSquare(size, depth):
    size = int(size)

    # Move to the top-right corner before drawing:
    turtle.penup()
    turtle.forward(size // 2)
    turtle.left(90)
    turtle.forward(size // 2)
    turtle.left(180)
    turtle.pendown()

    # Alternate between white and gray (with black border):
    if depth % 2 == 0:
        turtle.pencolor('black')
        turtle.fillcolor('white')
    else:
        turtle.pencolor('black')
        turtle.fillcolor('gray')

    # Draw a square:
    turtle.begin_fill()
    for i in range(4):  # Draw four lines.
        turtle.forward(size)
        turtle.right(90)
    turtle.end_fill()


def drawTriangleOutline(size, depth):
    size = int(size)

    # Move the turtle to the top of the equilateral triangle:
    height = size * math.sqrt(3) / 2
    turtle.penup()
    turtle.left(90)  # Turn to face upwards.
    turtle.forward(height * (2/3))  # Move to the top corner.
    turtle.right(150)  # Turn to face the bottom-right corner.
    turtle.pendown()

    # Draw the three sides of the triangle:
    for i in range(3):
        turtle.forward(size)
        turtle.right(120)


def drawFractal(shapeDrawFunction, size, specs, maxDepth=8, depth=0):
    if depth > maxDepth or size < 1:
        return  # BASE CASE

    # Save the position and heading at the start of this function call:
    initialX = turtle.xcor()
    initialY = turtle.ycor()
    initialHeading = turtle.heading()

    # Call the draw function to draw the shape:
    turtle.pendown()
    shapeDrawFunction(size, depth)
    turtle.penup()

    # RECURSIVE CASE
    for spec in specs:
        # Each dictionary in specs has keys 'sizeChange', 'xChange',
        # 'yChange', and 'angleChange'. The size, x, and y changes
        # are multiplied by the size parameter. The x change and y
        # change are added to the turtle's current position. The angle
        # change is added to the turtle's current heading.
        sizeCh = spec.get('sizeChange', 1.0)
        xCh = spec.get('xChange', 0.0)
        yCh = spec.get('yChange', 0.0)
        angleCh = spec.get('angleChange', 0.0)

        # Reset the turtle to the shape's starting point:
        turtle.goto(initialX, initialY)
        turtle.setheading(initialHeading + angleCh)
        turtle.forward(size * xCh)
        turtle.left(90)
        turtle.forward(size * yCh)
        turtle.right(90)

        # Make the recursive call:
        drawFractal(shapeDrawFunction, size * sizeCh, specs, maxDepth,
        depth + 1)


if DRAW_FRACTAL == 1:
    # Four Corners:
    drawFractal(drawFilledSquare, 350,
        [{'sizeChange': 0.5, 'xChange': -0.5, 'yChange': 0.5},
         {'sizeChange': 0.5, 'xChange': 0.5, 'yChange': 0.5},
         {'sizeChange': 0.5, 'xChange': -0.5, 'yChange': -0.5},
         {'sizeChange': 0.5, 'xChange': 0.5, 'yChange': -0.5}], 5)
elif DRAW_FRACTAL == 2:
    # Spiral Squares:
    drawFractal(drawFilledSquare, 600, [{'sizeChange': 0.95,
        'angleChange': 7}], 50)
elif DRAW_FRACTAL == 3:
    # Double Spiral Squares:
    drawFractal(drawFilledSquare, 600,
        [{'sizeChange': 0.8, 'yChange': 0.1, 'angleChange': -10},
         {'sizeChange': 0.8, 'yChange': -0.1, 'angleChange': 10}])
elif DRAW_FRACTAL == 4:
    # Triangle Spiral:
    drawFractal(drawTriangleOutline, 20,
        [{'sizeChange': 1.05, 'angleChange': 7}], 80)
elif DRAW_FRACTAL == 5:
    # Conway's Game of Life Glider:
    third = 1 / 3
    drawFractal(drawFilledSquare, 600,
        [{'sizeChange': third, 'yChange': third},
         {'sizeChange': third, 'xChange': third},
         {'sizeChange': third, 'xChange': third, 'yChange': -third},
         {'sizeChange': third, 'yChange': -third},
         {'sizeChange': third, 'xChange': -third, 'yChange': -third}])
elif DRAW_FRACTAL == 6:
    # Sierpinski Triangle:
    toMid = math.sqrt(3) / 6
    drawFractal(drawTriangleOutline, 600,
        [{'sizeChange': 0.5, 'yChange': toMid, 'angleChange': 0},
         {'sizeChange': 0.5, 'yChange': toMid, 'angleChange': 120},
         {'sizeChange': 0.5, 'yChange': toMid, 'angleChange': 240}])
elif DRAW_FRACTAL == 7:
    # Wave:
    drawFractal(drawTriangleOutline, 280,
        [{'sizeChange': 0.5, 'xChange': -0.5, 'yChange': 0.5},
         {'sizeChange': 0.3, 'xChange': 0.5, 'yChange': 0.5},
         {'sizeChange': 0.5, 'yChange': -0.7, 'angleChange': 15}])
elif DRAW_FRACTAL == 8:
    # Horn:
    drawFractal(drawFilledSquare, 100,
        [{'sizeChange': 0.96, 'yChange': 0.5, 'angleChange': 11}], 100)
elif DRAW_FRACTAL == 9:
    # Snowflake:
    drawFractal(drawFilledSquare, 200,
        [{'xChange': math.cos(0 * math.pi / 180),
          'yChange': math.sin(0 * math.pi / 180), 'sizeChange': 0.4},
         {'xChange': math.cos(72 * math.pi / 180),
          'yChange': math.sin(72 * math.pi / 180), 'sizeChange': 0.4},
         {'xChange': math.cos(144 * math.pi / 180),
          'yChange': math.sin(144 * math.pi / 180), 'sizeChange': 0.4},
         {'xChange': math.cos(216 * math.pi / 180),
          'yChange': math.sin(216 * math.pi / 180), 'sizeChange': 0.4},
         {'xChange': math.cos(288 * math.pi / 180),
          'yChange': math.sin(288 * math.pi / 180), 'sizeChange': 0.4}])
elif DRAW_FRACTAL == 10:
    # The filled square shape:
    turtle.tracer(1, 0)
    drawFilledSquare(400, 0)
elif DRAW_FRACTAL == 11:
    # The triangle outline shape:
    turtle.tracer(1, 0)
    drawTriangleOutline(400, 0)
else:
    assert False, 'Set DRAW_FRACTAL to a number from 1 to 11.'

turtle.exitonclick()  # Click the window to exit.