var lineAmount = 12;

​

​

class Point {

    constructor(x, y) {

        this.x = x;

        this.y = y;

    }

}

​

​

class LineClass {

    constructor(start, end) {//constructor assumes these are points

        this.start = start;

        this.end = end;

    }

}

​

function createLine() {

    start = new Point(0, 0);

    end = new Point(0, 0);

}

​

​

function setup() {

    createCanvas(640, 480);

    background(0);

​

}

​

function draw() { }

​

function mousePressed() {

    background(0);

    var slope1;

    var yintercept1;

    var slope2;

    var yintercept2;

    var intersectPt;

    var arraylist = [];

​

    //create and draw lines

    for (var counter = 0; counter < lineAmount; counter++) {

        //start

        var tempPoint1 = new Point(2, 0);

        var tempPoint2 = new Point(0, 0);

​

        var lin = new LineClass(tempPoint1, tempPoint2);

​

        lin.start.x = random(width);

        lin.start.y = random(height);

​

​

        //end

        lin.end.x = random(width);

        lin.end.y = random(height);

​

        arraylist.push(lin);

​

        stroke(0, 255, 0);

        line(lin.start.x, lin.start.y, lin.end.x, lin.end.y);

    }

​

    for (counter = 0; counter < arraylist.length; counter++) {

        //a "for in" loop didn't work here

        FindIntersectingLineInArray(arraylist[counter], arraylist);

    }

}

​

//we test every line and if it intersect with another line in arraylist we highliht that point

function FindIntersectingLineInArray(lineToTest, lineArrayList) {

    var reference_Slope = 0;

    var referenceY_Intecept = 0;

    var slope = 0;

    var yIntercept = 0;

    var interseptPoint;

​

    reference_Slope = (lineToTest.end.y - lineToTest.start.y) / (lineToTest.end.x - lineToTest.start.x);

    referenceY_Intecept = lineToTest.start.y - lineToTest.start.x * reference_Slope;

​

    for (counter = 0; counter < lineArrayList.length; counter++) {

        //a "for in" loop didn't work here as well

        slope = (lineArrayList[counter].end.y - lineArrayList[counter].start.y) / (lineArrayList[counter].end.x - lineArrayList[counter].start.x);

        yIntercept = lineArrayList[counter].start.y - lineArrayList[counter].start.x * slope;

        if (reference_Slope != slope) {

            lineLine(lineToTest.start.x, lineToTest.start.y, lineToTest.end.x, lineToTest.end.y, lineArrayList[counter].start.x, lineArrayList[counter].start.y, lineArrayList[counter].end.x, lineArrayList[counter].end.y);

        }

    }

}

​

// LINE/LINE  Jeffrey Thomas Line intersection collision math

function lineLine(x1, y1, x2, y2, x3, y3, x4, y4) {

​

    // calculate the distance to intersection point

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

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

​

    // if uA and uB are between 0-1, lines are colliding

    if (uA >= 0 && uA <= 1 && uB >= 0 && uB <= 1) {

​

        //draw a circle where the lines meet

        var intersectionX = x1 + (uA * (x2 - x1));

        var intersectionY = y1 + (uA * (y2 - y1));

        fill(255, 0, 0);

        ellipse(intersectionX, intersectionY, 7, 7);

​

        return true;

    }

    return false;

}