# rigatoni – Intersections01

via GIPHY

```let redraw = true function setup() { createCanvas(400, 400); }   function draw() { if(redraw) { background(180); var lineArray = new LineArray(20) lineArray.draw() redraw = false } }   function mouseClicked() { redraw = true }   // CLASS CONSTRUCTORS //   function LineArray(lineCount) { this.lines = [] for(i=0; i<lineCount; i++) { this.lines[i] = new Line(random(width), random(width), random(width), random(width)) }   this.draw = function(displayIntersections=false) { for(i=0; i<lineCount; i++) { this.lines[i].draw() for(j=0; j<i; j++) { var intersection = getIntersection(this.lines[j], this.lines[i]) fill(0,0,0) if(isWithinSegment(intersection, this.lines[i]) && isWithinSegment(intersection, this.lines[j])) { ellipse(intersection[0], intersection[1], 5, 5) } } } } }   function Line(x1, y1, x2, y2) { this.x1=x1 this.y1=y1 this.x2=x2 this.y2=y2   this.draw = function() { stroke(5) line(this.x1, this.y1, this.x2, this.y2) } }   //HELPER METHODS //   // All the calculations here were informed by Paul Bourke's work // http://paulbourke.net/geometry/pointlineplane/ function getIntersection(line1, line2) { var coef = (line2.x2-line2.x1)*(line1.y1-line2.y1) coef -= (line2.y2-line2.y1)*(line1.x1-line2.x1) var denom = (line2.y2-line2.y1)*(line1.x2-line1.x1) denom -= (line2.x2-line2.x1)*(line1.y2-line1.y1) coef = coef/denom   var x = line1.x1 + coef*(line1.x2-line1.x1) var y = line1.y1 + coef*(line1.y2-line1.y1) var intersection = [x,y] return intersection }   // I learnt how to do cross & dot products from here: // https://stackoverflow.com/questions/328107 // heavily based on the pseudocode written by user Cyrille Ka function isWithinSegment(p, seg) { let x1 = min(seg.x1, seg.x2) let y1 = min(seg.y1, seg.y2) let x2 = max(seg.x1, seg.x2) let y2 = max(seg.y1, seg.y2)   if((p[0]>=x1 && p[0]<=x2 && p[1]>=y1 && p[1]<=y2)==false) { return false } return true }```