Drawing Trees with Python’s Turtle Module

Python’s turtle module is a popular choice for introducing beginners to the concepts of programming and graphics. It provides a simple yet powerful way to draw shapes and patterns using a virtual “turtle” cursor. In this blog post, we will explore how to use the turtle module to draw trees, a classic fractal pattern that can be created recursively.

Introduction to Turtle Graphics

Turtle graphics is a popular way to teach programming concepts visually. It allows users to control a virtual turtle cursor on a canvas and direct it to move around and draw lines. The turtle module comes with a set of commands that can be used to manipulate the turtle’s movement, such as forward(), backward(), left(), right(), and more.

Drawing Trees with Turtle

Drawing trees using turtle graphics can be achieved by employing the concept of recursion. A recursive function is a function that calls itself, often with modified parameters, to generate patterns or solve problems. In the case of drawing trees, we can define a recursive function that draws the trunk of the tree and then calls itself to draw smaller branches recursively.

Here’s an example of how to draw a basic tree using the turtle module:

pythonimport turtle

def draw_tree(t, branch_len, t_angle):
    if branch_len < 3:
        return

    # Draw the current branch
    t.forward(branch_len)
    t.right(20)  # Change this angle to modify the tree's shape
    
    # Draw the left sub-branch
    draw_tree(t, branch_len - 15, t_angle + 20)
    
    # Draw the right sub-branch
    t.left(40)  # Total angle change should be 60 degrees for a balanced tree
    draw_tree(t, branch_len - 15, t_angle - 20)
    
    # Go back to the start of the current branch
    t.right(20)
    t.backward(branch_len)

# Set up the turtle
tree = turtle.Turtle()
tree.speed(1)
tree.left(90)  # Start drawing vertically
tree.up()
tree.backward(100)  # Move the turtle to the top of the canvas
tree.down()
tree.color("brown")  # Set the color for the trunk

# Draw the trunk
tree.forward(30)

# Change the color for the branches
tree.color("green")

# Draw the tree recursively
draw_tree(tree, 60, 90)

# Keep the window open
turtle.done()

In this example, we define a recursive function draw_tree() that takes a turtle object t, the length of the current branch branch_len, and the angle t_angle at which the branch is pointing. The function first checks if the branch length is less than a threshold (in this case, 3) and returns if it is, preventing infinite recursion. It then draws the current branch using forward() and adjusts the angle using right(). Next, it recursively calls itself to draw the left and right sub-branches, passing modified parameters. Finally, it goes back to the start of the current branch using backward().
By adjusting the parameters such as the initial branch length, angle change, and recursion depth, you can create different shapes and sizes of trees.
Conclusion
Drawing trees with Python’s turtle module is a fun and educational exercise. It combines the concepts of recursion and graphics to create visually appealing patterns. The turtle module provides a simple yet powerful platform for exploring computational graphics and fractals, making it a valuable tool for teaching and learning programming.