C# Turtle Graphics library - for teaching kids to code.

This library provides а very simple "turtle graphics" drawing interface for C#, designed for kids, learning to code, or teachers who want to illustrate programming visually.

1. Create a new empty Windows Form application with Visual Studio.
2. Install the NuGet package "Nakov.TurtleGraphics" from the Package Management Console in Visual Studio:

Install-Package Nakov.TurtleGraphics

3. Put a button [Draw]. Handle the Click event and add this code:

// Assign a delay to visualize the drawing process
Turtle.Delay = 200;

// Draw a equilateral triangle
Turtle.Rotate(30);
Turtle.Forward(200);
Turtle.Rotate(120);
Turtle.Forward(200);
Turtle.Rotate(120);
Turtle.Forward(200);

// Draw a line in the triangle
Turtle.Rotate(-30);
Turtle.PenUp();
Turtle.Backward(50);
Turtle.PenDown();
Turtle.Backward(100);
Turtle.PenUp();
Turtle.Forward(150);
Turtle.PenDown();
Turtle.Rotate(30);

4. Enjoy the application:

See the full source code here: https://github.com/nakov/TurtleGraphics.NET/tree/master/Turtle-Graphics-Example.

The interface is intentionally simplified through a single static class (I know this is not a good practice in OOP), to enable kids start playing with the turtle with just few clicks, without knowing anything about "classes" and "objects". The class Turtle supports all major turtle graphics primitives in Windows Forms C# / .NET GUI applications:

• Init() - initializes the turtle graphics system. Callers can specify the target Windows Forms control to hold the drawing surface (e.g. a Panel). If not specified, the currently active form is used as drawing surface. If not called, it will be called on demand with the first turtle move / draw command. Initially the turtle location is {0, 0} (the screen center) and the direction (angle) is 0 degrees (up).
• Dispose() / Reset() - destroys the turtle graphics system and deallocates all resources, associated with it.
• Forward(distance) - moves the turtle forward in the current direction by the specified distance. If the pen is down, the turtle draws a line from the current to the new position, otherwise it just moves without leaving a track.
• Backward(distance) - moves the turtle in backward direction and draws a line if the pen is down.
• MoveTo(x, y) - moves the turtle to the specified position and draws a line if the pen is down.
• Rotate(angle) - rotates the turtle relatively to the current direction. The rotation angle is given in degrees (e.g. 45, -30, 315, ...).
• RotateTo(angle) - rotates the turtle to the specified angle in degrees (e.g. 0, 45, 180, 315, ...).
• PenUp() - moves the pen up (makes further moves invisible). Further calls to Forward(distance) / Backward(distance) / MoveTo(x, y) will move the turtle without drawing a line.
• PenDown() - moves the pen down (makes further moves visible). Further calls to Forward(distance) / Backward(distance) / MoveTo(x, y) will draw a line from the current to the new position.
• X - gets / sets the current turtle horizontal position. The initial turtle position is the screen center {0, 0}. Increasing X will move the turtle right.
• Y - gets / sets the current turtle vertical position. The initial turtle position is the screen center {0, 0}. Increasing Y will move the turtle up.
• Angle - gets / sets the current turtle direction (angle in degrees). The value of 0 means up, 90 means right, 180 means down and 270 means left. The Angle is always kept in the range [0...360). Initially the angle is 0.
• PenColor - gets / sets the color of the pen. The default pen color is "blue".
• PenSize - gets / sets the size of the pen (in pixels). The default pen size is 7.
• PenVisible - gets / sets the visibility of the pen. The default pen size is true. True means the pen is down (draws a line when the turtle moves). False means the pen is up (no line is drawn when the turtle moves).
• ShowTurtle - gets / sets whether the turtle is visible. By default it is visible.
• Delay - gets / sets the turtle delay in milliseconds after moving / rotating. By default the delay is 0 (no delay). Setting the delay to 100-300 will simulate a pleasant "animation effect". Delay is preserved after Reset().