lindertree

A lsystem generator and interpreter.

Features

• Standard 2D turtle interpretation of produced lsystems.
• Simple rule specifications using string to symbols parsing.
• Parametric rule specification and turtle interpretation.
• Stochastic rules, parameters and drawing deviation.
• [TODO] Command line interface.
• [TODO] Load axioms and rules from file.
• [TODO] Speed optimization using a fast gui.

Usage

See example.py and example_parametric.py.

Format

Symbols

A valid symbol is composed of one alphabetic character or one of [, ], +, -, !.

Turtle interpreted symbols

• F : draw forward.
• f : move forward without drawing.
• + : rotate left.
• - : rotate right.
• [ : start branch (push turtle state on the stack).
• ] : end branch (pop turtle state from the stack).
• X : standard non-interpreted symbol used for developmental control

Parametric symbols

A valid parametric symbol is composed of one alphabetic character or one of [, ], +, -, !. It may be followed by non-nested parentheses containing the parameters separated by ,. A parameter must be a valid identifier of the form [A-Za-z]+[A-Za-z\d]* or a valid integer or float (with a . before decimals). Note that the parser automatically convert integers to floats. For now, there is no input validation, so beware ! You may also use +, -, / and * for operations in rules. To compute parameters on the fly, we use eval() so beware again !

Turtle interpreted parametric symbols

• F(x) : draw x pixels forward.
• T(x, y) : draw x pixels forward with width y.
• f(x) : move x pixels forward without drawing.
• +(x) : rotate of x angle (x > 0 means counterclockwise, x < 0 means clockwise).
• !(x) : set width to x pixels.

Random

3 kinds of random are provided :

• Stochastic rules with the StochasticRule class.
• Stochastic parameters with ^ for polar random [0,1] and ~ for bipolar random [-1,1]
• Stochastic drawing with distance_dev and angle_dev : (proportional_offset, proportional_scale, uniform_offset, uniform_range).

Examples

example.py :

• Axiom : $X$
• Rules :
  • $F \rightarrow FF$
  • $X \rightarrow F[+X][-X]FX$

example_parametric.py :

• Axiom : $!(1)F(5)X$
• Constants : $w=5, e=1.6, a=1.1$
• Rules :
  • $!(x) \rightarrow !(x*w)$
  • $F(x) \rightarrow F(x*e)$
  • $+(x) \rightarrow +(x*a)$
  • $-(x) \rightarrow -(x*a)$
  • $X \rightarrow!(1)[+(25)F(2)X]F(2)[-(25)F(2)X]!(1)F(5)X$