flow-field.js

// A 2D polyline of samples along a flow field
let path = [ penStart ];

let [ x, y ] = penStart;
for (let i = 0; i < steps; i++) {
  // Get new angle of rotation
  const angle = noise(x, y) * angleAmplitude;
  // Offset the point by this angle
  x += Math.cos(angle) * stepSize;
  y += Math.sin(angle) * stepSize;
  // Add the new sample
  path.push([ x, y ]);
}