[L-system tree] How to build an L-system tree in Manim. #manim #lsystem #dataclasses #artist #tree #animate

29221993_tree.py

# code by @Maieutic
# https://discord.com/channels/581738731934056449/1026221281810579556/1026253177177255957

from dataclasses import dataclass
from manim import *
import numpy as np

L_SYSTEM = {
    "axiom": "F",
    "rules": {"F": "F[-F][+F]", "+": "+", "-": "-", "[": "[", "]": "]"},
    "iterations": 5,
    "length": 0.5,
    "degrees": 25,
    "inital_degrees": 90,
    "start": np.array([0, -1, 0]),
}


class Tree(Scene):
    def construct(self):
        (
            axiom,
            rules,
            iterations,
            length,
            degrees,
            initial_degrees,
            start,
        ) = L_SYSTEM.values()
        system = LSystem(axiom, rules, iterations)
        artist = LSystemArtist(system, length, degrees, initial_degrees, start)
        self.play(Create(artist.tree))
        self.wait(2)


class LSystemArtist:
    def __init__(self, system, length, degrees, initial_degrees, start):
        self.system = system
        self.commands = {
            "F": self.forward,
            "+": self.rotate_left,
            "-": self.rotate_right,
            "[": self.save,
            "]": self.restore,
        }
        self.theta = initial_degrees * PI / 180
        self.rotation = degrees * PI / 180
        self.length = length
        self.start = start
        self.positions = []
        self.rotations = []
        self.tree = VGroup()
        self.draw_system()

    def draw_system(self):
        for instruction in self.system.instructions:
            if instruction in self.commands.keys():
                self.commands[instruction]()

    def forward(self):
        end = (
            self.start
            + (self.length * np.cos(self.theta) * RIGHT)
            + (self.length * np.sin(self.theta) * UP)
        )
        new_line = Line(start=self.start, end=end)
        self.start = end
        self.tree.add(new_line)

    def rotate_left(self):
        self.theta += self.rotation

    def rotate_right(self):
        self.theta -= self.rotation

    def save(self):
        self.positions.append(self.start)
        self.rotations.append(self.theta)

    def restore(self):
        self.start = self.positions.pop()
        self.theta = self.rotations.pop()


class LSystem:
    def __init__(self, axiom, rules, iterations):
        self.rules = rules
        self.iterations = iterations
        self.instructions = axiom
        self.create_instructions()

    def create_instructions(self):
        new_string = ""
        for _ in range(self.iterations):
            new_string = ""
            for character in self.instructions:
                new_string += self.rules[character]
            self.instructions = new_string

readme.md

https://discord.com/channels/581738731934056449/1026221281810579556/1026253177177255957