# **Turtle Graphics** Turtle Graphics is a feature built into Python that allows users to create basic drawings and two-dimensional geometric shapes. It provides a simple and interactive way for beginners to learn programming concepts visually. The library is pre-installed with Python and can be used to develop animations, simulations, and simple computer games. --- ## **1. Getting Started** To begin using Turtle Graphics, you must first import the library and create a drawing canvas. - **Importing the Library:** The first step is to make the turtle library's functions available in your program. - `import turtle` - **Creating the Canvas:** A window or canvas is needed for the drawing to appear. This is often called the *screen*. - `turtle.Screen()`: This command loads the white canvas where drawings will appear. - **The Turtle (Pen):** A small arrow-like shape (`>`) appears on the screen. This is the "turtle," which acts as the pen that draws lines and shapes. All drawing commands are executed from the turtle's current position and orientation. ## **2. Screen and Pen Configuration** You can customize the appearance of the canvas and the pen. - **Screen Size and Color:** - `turtle.screensize(width, height, "color")`: Resizes the canvas and sets its background color. *Measurements are in pixels*. - *Example:* `turtle.screensize(200, 150, "coral")` - **Pen Color:** - `turtle.pencolor("color")`: Changes the color of the lines drawn by the turtle. The default color is *Black*. - *Example:* `turtle.pencolor("Blue")` - **Canvas Control:** - `turtle.reset()`: Clears the entire canvas and returns the turtle to its starting position in the center. ## **3. Drawing Commands** These functions control the turtle's movement and drawing actions. - **Movement:** - `turtle.forward(distance)`: Moves the turtle forward in its current direction by a specified number of *pixels*. - `turtle.back(distance)`: Moves the turtle backward by a specified number of *pixels*. - **Rotation:** - `turtle.left(angle)`: Rotates the turtle counter-clockwise by a specified angle. *The angle is in degrees by default*. - `turtle.right(angle)`: Rotates the turtle clockwise by a specified angle in *degrees*. - **Pen Control:** - `turtle.penup()`: Lifts the pen from the canvas. The turtle can move to a new location without drawing a line. - `turtle.pendown()`: Puts the pen back down on the canvas, so it will draw when it moves. - **Drawing Shapes:** - `turtle.circle(radius)`: Draws a circle with a given radius. A *negative radius* value draws the circle in the opposite direction (clockwise). - `turtle.dot(size, "color")`: Draws a filled circle (a dot) of a specific size and color at the turtle's current position. ## **Example Code & Diagrams** **Drawing Circles and a Dot:** The following code sets up the screen, draws a dot, and then two circles with different colors and directions. ```python 1. import turtle 2. turtle.Screen() 3. turtle.screensize(200,150,"coral") 4. turtle.dot(10,"Blue") 5. turtle.circle(50) 6. turtle.pencolor("Blue") 7. turtle.circle(-50) ``` **Drawing a Triangle:** This example demonstrates combining forward movements with left turns to create a closed shape. ```python 1. turtle.reset() 2. turtle.forward(140) 3. turtle.left(135) 4. turtle.forward(100) 5. turtle.left(90) 6. turtle.forward(100) ``` **Drawing a Complex Shape (Car):** This code snippet shows how `penup()` and `pendown()` are used to create a non-contiguous shape like a car with wheels. | Line | Command | Line | Command | | :--- | :--- | :--- | :--- | | 1. | `turtle.forward(100)` | 18. | `turtle.left(90)` | | 2. | `turtle.left(90)` | 19. | `turtle.forward(25)` | | 3. | `turtle.forward(25)` | 20. | `turtle.pendown()` | | 4. | `turtle.left(90)` | 21. | `turtle.circle(-10)` | | 5. | `turtle.forward(25)` | 22. | `turtle.penup()` | --- ## **Possible Questions/Answers** - **Q:** Do I need to install Turtle Graphics separately? **A:** No, it is a standard library that comes installed with Python. You just need to `import turtle`. - **Q:** What is the "turtle"? **A:** The "turtle" is the on-screen pen or cursor that you control with commands to draw lines and shapes on the canvas. - **Q:** How can I move the turtle to a new position without drawing a line? **A:** Use `turtle.penup()` to lift the pen, move the turtle with `forward()` or `back()`, and then use `turtle.pendown()` to start drawing again. - **Q:** What units are used for distance and angles? **A:** Distances for functions like `forward()` are measured in *pixels*. Angles for functions like `left()` and `right()` are measured in *degrees* by default. --- ## **Summary** - **Introduction:** Turtle Graphics is a beginner-friendly, built-in Python library for creating 2D graphics. - **Core Components:** It operates with a *turtle* (pen) on a *Screen* (canvas). - **Basic Operations:** Key operations include setting up the screen, moving the turtle, changing its direction, and controlling the pen's state (up/down/color). - **Key Functions:** | Function | Purpose | | :--- | :--- | | `import turtle` | Loads the library. | | `turtle.Screen()` | Creates the drawing canvas. | | `turtle.forward(px)` | Moves the turtle forward. | | `turtle.left(deg)` | Turns the turtle left. | | `turtle.circle(r)` | Draws a circle. | | `turtle.penup()` | Lifts the pen to move without drawing. | | `turtle.pendown()` | Puts the pen down to resume drawing. | | `turtle.pencolor(c)` | Changes the drawing color. | | `turtle.reset()` | Clears the screen. | - **Significance:** It provides an excellent visual and interactive tool for learning fundamental programming concepts like sequencing, functions, and (with further exploration) loops and conditions. --- ## **References** (Derived from FBISE textbook)