W2514 Emergence & Lindenmayer Systems (Part 4)
- Read Stacks
- Review those Lindenmayer Systems that require use of a stack (pop/push). One example is a "Fractal Tree".
Modify the code from your previous experience.
Turtle objects are able to remember their current state and restore that state at a later point. The state is stored on a stack and is therefore in LIFO (Last In First Out) order. A turtle's state includes:
- pen color
- pen width
Consider a Fractal Tree with the following translation mechanisms:
- 0: draw a line segment (ending in a leaf)
- 1: draw a line segment
- [: push position and angle, turn left 45 degrees
- ]: pop position and angle, turn right 45 degrees
When encountering a push or pop operation we can use the turtle's functionality as follows:
case "[": turtle.push() turtle.left(degrees:45) case "]": turtle.pop() turtle.right(degrees:45)
Regardless of what occurs between a push and a pop, the turtle will be in the same situation it was in immediately prior to the push. This enables us to build very complex systems, such as Kev's Wispy Tree.
- Alphabet: "F", "X", "[", "]", "+", "-", "0", "1", "2", "3"
- Axiom: "FX"
- Production Rules:
- "F" -> "0FF-[1-F+F]+[2+F-F]"
- "X" -> "0FF+[1+F]+[3-F]"
- Geometric mechanism:
- "F" -> Forward
- "X" -> Forward
- "-" -> Right 25 degrees
- "+" -> Left 25 degrees
- "[" -> Push
- "]" -> Pop
- "0" -> Pen color: red:140, green:80, blue:60
- "1" -> Pen color: red:24, green:180, blue:24
- "2" -> Pen color: red:48, green:220, blue:48
- "3" -> Pen color: red:64, green:255, blue:64
👀 See Also
- Adapted from http://www.kevs3d.co.uk
- Add a Fractal Tree as one of the Lindenmayer Systems in your cycle
- Add a Fractal Plant as one of the Lindenmayer Systems in your cycle
- Add "Kevs Wispy Tree" as one of the Lindenmayer Systems in your cycle
- Add buttons to alter the angles used in drawing the L-Systems
- Construct your own Lindenmayer System and add it to your cycle
- Animate the entire production of the Lindenmayer System (not just from generation to generation, but the application of each production rule in sequence)
- A Stack is an abstract data-type which is a collection of elements with two principal operations:
- Push adds the specified element to the collection
- Pop removes and returns the most recently added element
- LIFO means Last in, first out