Draw patterns

In the following video the turtle draws several patterns. Create a new project for each of them and try to reproduce the patterns as closely as possible.

Here are some hints for each pattern that should get you started:

• Horizontal saw
  • At the beginning move the turtle to the left edge. Use Game.SceneBounds.Left to get the X coordinate of the left edge. The y coordinate is the center of the scene.
  • Turn on the pen and alternately move the turtle diagonally up and down.
  • Repeat the movement until the turtle’s X position is greater than Game.SceneBounds.Right.
• Vertical saw
  • Same as above, but the turtle should move from Game.SceneBounds.Top to Game.SceneBounds.Bottom.
• Cross saw
  • Independent of the scene size the turtle should move from the top left corner to the bottom right corner.
  • Imagine a line between the two corners that the turtle should follow. It might help to have the turtle look along that line.
  • Now turn about 45 degrees counter-clockwise and draw the first line.
  • Turn back and move to your imaginary line so that the turtle draws a normal on it.
  • Continue drawing the two lines until the turtle is at the bottom right corner.
• Sine wave - Version 1
  • Make sure you know how a sine wave looks like before you start.
  • Start at the left edge and calculate the sine of the current X coordinate using Math.Sin.

    Math.Sin works with radians, but we want our X coordinates to be interpreted as degrees. To do that we have to convert the X coordinate to radians before passing it to Math.Sin. The value we get back from Math.Sin is between -1 and 1 (that’s how sine is defined). Basically this is now the value that we use as y coordinate. However we should scale the value (i.e. multiply it by e.g. 100) before moving the turtle to that position.

  • Calculate the y coordinate for the next X coordinate (you get a better resolution the smaller x steps you make) according to the above procedure until you hit the right edge.
• Sine wave - Version 2
  • Instead of simply moving the turtle along the curve we draw a straight line from the scene bottom to the y value.
• Sine wave - Version 3
  • In addition to the line from the bottom edge to the y value we draw another line with a different color from the y value to the top edge.
• Cosine wave
  • Find the command that calculates the cosine and draw the curve according to “Sine wave - Version 1”.
• Tangent wave
  • Find the command that calculates the tangent and draw the curve according to “Sine wave - Version 1”.
• Christmas tree - Version 1
  • Similar to “Vertical saw”, but the horizontal line is not as long.
  • You probably need two loops to draw both sides of the tree.
• Christmas tree - Version 2
  • Continuously increase the x distance until you hit the bottom edge. The y distance should be constant.
• Sawing blade
  • You have multiple options here:
    1. Use a loop to draw a single blade. Use another loop to draw several blades. You’ll end up having a loop inside a loop.
    2. Use a single loop to draw the whole saw. Continuously increase the length of the line. When the length of the line reaches a certain threshold, reset the length to its original value.
  • The easiest way to draw a single line is probably having the turtle to look in the right direction and then move forward and backward.
• Flower
  • You again have multiple options:
    1. Use a loop to draw half of a petal and another loop next to it to draw the other half. Use a third loop to draw multiple petals. You’ll end up having a loop with two loops in it.
    2. Use a loop to draw a petal. Inside the loop the length of the line is continuously increased. When the length hits a certain threshold it is continuously decreased (Hint: Adding a positive value increases the length, adding a negative value decreases the length). Use another loop to draw several petals. You’ll end up having a loop inside a loop.
    3. Use a loop to draw the whole flower. You’ll need the same logic as before to increase and decrease the length of the line.