spiral_triangle

Wish

I usually doodle it and I wanted to recreate it in Python (see output).

Here's what the code is doing

spiral_triangle.py

Following explanation is for spiral_triangle.py. Also, it is to note that I developed this logic thinking that I will be drawing the triangle as horizontally aligned (turtle starts facing East) and not at an angle (turtle not headed say at 20 degrees North of East). I modified this in spiral_triangles_using_class.py

1. I created a drawing board using turtle module's Screen method. I changed my turtle's shape to circle using shape method. I moved the turtle to x=-90, y=-90 using penup, goto, pendown method. I have used speed() method with 0 argument, as 0 makes the turtle move fastest possible.
2. Then, I defined polygon parameters. n denotes the number of sides in a polygon. n=3 denotes that it's a triangle. polygon_turn_angle is exterior angle of the polygon.
3. See illustred image Construction of Spiral triangle to get the definition of polygon_side_length, segment_length variables.
4. Initially, triangle's first side is drawn using turtle module's forward method. The trick to draw the spiral triangle is, when I am drawing the second side of triangle, I am not drawing it in one go.
   1. Firstly, I drew the segment_length. Here I used turtle's position method to get current location's x,y co-ordinates. I stored this in the list pt.
   2. Then I continued and marched forward polygon_side_length-segment_length distance to complete the second side of triangle.
   3. Similar actions are done when drawing the third side.
5. To draw the first inward line segment (side_length_1) of the spiral, I utilized that point whose x,y co-ordinates I stored in pt list while drawing second side of the triangle. After drawing the third side of the triangle:
   1. I used turtle module's distance method to get the distance between current location and the point on the second side of the triangle. (Since I am back to starting point after completing the triangle, current location is starting point). Then I utilized towards method to get the angle towards that point.
   2. Then I used left method to orient the turtle's head towards that point on the second side of triangle.
   3. Finally I used forward method to march and complete the spiral's first inward line segment side_length_1. Step 4's actions are executed in between to get the information of point on this side_length_1 as this will help to draw the next side_length_1.
   4. I am doing this over and over in for loop. I used if conditional to break out of the for loop if spiral's side_length_1 becomes < 1.

spiral_triangle_using_class.py

I have hardcoded the number of sides in polygon n=3 for triangle. This can be modified and the code will work for any polygon.

Construction of spiral triangle

Spiral triangle

output of spiral_triangle.py

output of spiral_triangle_using_class.py

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