Drawbot interpretation of https://tylerxhobbs.com/essays/2020/flow-fields

flow_lines.py

# from https://tylerxhobbs.com/essays/2020/flow-fields

import math
import random

# You need to pip install this in Drawbot
# (i.e., go to Python > Install Python Packages and copy in perlin_noise and select install)
from perlin_noise import PerlinNoise


def remap(v, min, max, newMin, newMax):
    return ((v-min)/(max-min))*(newMax-newMin)+newMin

size(1000,1000)
left_x = int(width() * -0.5)
right_x = int(width() * 1.5)
top_y = int(height() * -0.5)
bottom_y = int(height() * 1.5) 
resolution = int(height() * 0.01) 
noise = PerlinNoise()
num_columns = (right_x - left_x) // resolution
num_rows = (bottom_y - top_y) // resolution

grid = []

for x in range(num_rows):
    column = []
    sangle = random.uniform(0, pi)
    for y in range(num_columns):
        scaled_x = x * 0.005
        scaled_y = y * 0.005
        noise_val = noise((scaled_x, scaled_y))
        angle = remap(noise_val,0.0,1.0,0.0,2.0*pi)
        column.append(angle)
    grid.append(column)

def draw(x,y, steps, step_length, color):
    path = BezierPath()
    path.moveTo((x,y))

    for n in range(0,steps):
        if n != 0:
            path.lineTo((x,y))
        
        x_offset = x - left_x
        y_offset = y - top_y
    
        column_index = int(x_offset / resolution)
        row_index = int(y_offset / resolution)
        if column_index >= len(grid):
            column_index = len(grid)-1
        if column_index < 0:
            column_index = 0
        if row_index >= len(grid[0]):
            row_index = len(grid[0])-1
        if row_index < 0:
            row_index = 0
        grid_angle = grid[column_index][row_index]

    
        x_step = step_length * cos(grid_angle)
        y_step = step_length * sin(grid_angle)
    
        x = x + x_step
        y = y + y_step

    stroke(color)
    fill(None)
    strokeWidth(2)
    path.endPath()
    drawPath(path)


step_length = 10

xrange = range(0,width())
yrange = range(0,height())

for s in range(600):
    x = choice(xrange)
    y = choice(yrange)
    steps = choice(range(int(height()/20),height()))
    color = remap(s,0,599,.1,.9)
    draw(x,y,steps,step_length, color)

saveImage("~/Desktop/flowpath.png")