Lightning Tree

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var pathPoints = []

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function setup() {

  createCanvas(800,800)

  background(0);

}

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function draw() {

  //stroke(255,opacity);

  translate(400,height);

  //var angle = random(0,6.14);

  var angle = 0.6//random(0.5,0.7);

  let opacity = 50

  branch(281,angle,opacity);

}

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function branch(len,theta,opacity) {

  //line(0,0,0,-len);

  var start = createVector(0,0)

  var end = createVector(0,-len)

  drawComplexPath(start,end,opacity)

  translate(0,-len);

  opacity *= 0.7 

  //var a = random(1.0);

  var a = 0 //random(0,0.1)

  if(len>2){

    push();

      rotate(theta);

      branch(0.618*len,theta,opacity);

    pop();

    push();

      rotate(-theta);

      branch(0.618*len,theta,opacity);

    pop();

  }

}

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function drawComplexPath(start,end,opacity) {

  let pathPoints = [start,end]

  for(var j=0;j<6;j++){

    pathPoints = complexifyPath(pathPoints);

  }

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  //draw the path

 stroke(255,opacity);

  for(var i=0;i<pathPoints.length -1;i++){

    var v1 = pathPoints[i];

    var v2 = pathPoints[i+1];

    line(v1.x,v1.y,v2.x,v2.y);

  }

}

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function complexifyPath(pathPoints){

  //create a new path array from the old one by adding new points inbetween the old points

  var newPath = [];

  for(var i=0;i<pathPoints.length -1;i++){

    var v1 = pathPoints[i];

    var v2 = pathPoints[i+1];

    var midPoint = p5.Vector.add(v1, v2).mult(0.5);

    var distance =  v1.dist(v2);

    //the new point is halfway between the old points, with some gaussian variation

    var standardDeviation = 0.125*distance;

    var v = createVector(randomGaussian(midPoint.x,standardDeviation),randomGaussian(midPoint.y,standardDeviation))

    append(newPath,v1);

    append(newPath,v);

  }

  //don't forget the last point!

  append(newPath,pathPoints[pathPoints.length-1]);

  return newPath;  

}

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