// Intersection mathematics by Paul Bourke

http://www-cs.ccny.cuny.edu/~wolberg/capstone/intersection/Intersection%20point%20of%20two%20lines.html

*/

​

​

var nSegments = 12;

var segments = [];

​

function setup() {

  createCanvas(400, 400);

  makeNewArrangement();

}

​

function draw() {

  background(220);

  stroke(0);

  for (var i = 0; i < nSegments; i++) {

    segments[i].render();

  }

​

  for (var i = 0; i < nSegments; i++) {

    var x1 = segments[i].xa;

    var y1 = segments[i].ya;

    var x2 = segments[i].xb;

    var y2 = segments[i].yb;

​

    for (var j = 0; j < i; j++) {

        var x3 = segments[j].xa;

        var y3 = segments[j].ya;

        var x4 = segments[j].xb;

        var y4 = segments[j].yb;

​

        var denom = (y4 - y3) * (x2 - x1) - (x4 - x3) * (y2 - y1);

        var ua = ((x4 - x3) * (y1 - y3) - (y4 - y3) * (x1 - x3)) / denom;

        var ub = ((x2 - x1) * (y1 - y3) - (y2 - y1) * (x1 - x3)) / denom;

        if ((ua >= 0) && (ua <= 1) && 

            (ub >= 0) && (ub <= 1)) {

          var px = x1 + ua * (x2 - x1);

          var py = y1 + ua * (y2 - y1);

          ellipse(px, py, 6, 6);

        }

    }

  }

}

​

function mousePressed() {

  makeNewArrangement();

}

​

function makeNewArrangement() {

  for (var i = 0; i < nSegments; i++) {

    segments[i] = new LineSegment(

      random(0, width),

      random(0, height),

      random(0, width),

      random(0, height)

    );

  }

}

​

​

class LineSegment {

  constructor(xa, ya, xb, yb) {

    this.xa = xa;

    this.ya = ya;

    this.xb = xb;

    this.yb = yb;

  }

  render() {

    line(this.xa, this.ya, this.xb, this.yb);

  }

}