​

let colors = [];

​

let polygons = [];

​

const markersize = 5;

​

function setup() {

  createCanvas(400, 400);

  background(255);

  //draw points

  for(let a=0;a<p.length;a++){

    drawMarker(p[a][0],p[a][1],0);

    colors.push(random(255));

  }

  for(let a=0;a<3;a++){

    print('STARTING NEW POLYGON')

    //draw lines for all other points

    let c = [];

    let s = [];

    let my = []; // on which side of line is point

    let mx = []; // where is the middle x of the line

    let pdist = sqrt(width**2 + height**2);

    let l1;

    for(let b=0;b<p.length;b++){

      if(b!=a){

        c[b] = ((p[b][0]-p[a][0]) / (p[a][1]-p[b][1]));

        s[b] = ((p[a][1]+p[b][1])/2 - c[b] * (p[a][0]+p[b][0]) / 2);

        //AB = c*x + s

        my[b] = (p[a][1] + p[b][1]) / 2; //1 if a is right of b, -1 if a is left

        mx[b] = (p[a][0] + p[b][0]) / 2;

        if(sqrt((p[a][0]-p[b][0])**2 + (p[a][1]-p[b][1])**2) < pdist){

          pdist = sqrt((p[a][0]-p[b][0])**2 + (p[a][1]-p[b][1])**2);

          l1 = b;

        }

      }

      else{

        c[b] = 'n/a';

        s[b] = 'n/a';

        my[b] = 'n/a';

        mx[b] = 'n/a';

      }

    }

    my.push((0+p[a][1])/2, (height+p[a][1])/2, p[a][1], p[a][1]);

    mx.push(p[a][0], p[a][0], (0+p[a][0])/2, (width+p[a][0])/2);

    //create array to store polygon points

    let pol = [];

    print('coefficients: ' + c + ' , shifts: ' + s + ' , middle x: '  + mx + ' , middle y: ' + my);

    //draw lines

    stroke(0);

    for(let l=0;l<c.length;l++){

      if(c[l] != 'n/a'){

        line(0,c[l]*0+s[l],400,c[l]*400+s[l]);

      }

    }

    noStroke();

    // find intersections with current line

    let insec = findLineIntersections(l1,c,s);

    print(insec)

    //draw and print intersections

    drawIntersections(insec);

    //find closest intersection

    let curdist = sqrt(width**2 + height**2);

    let curint;

    for(let i=0; i<insec.length; i++){

      if(sqrt((p[a][0]-insec[i][0])**2 + (p[a][1]-insec[i][1])**2) < curdist){

        curdist = sqrt((p[a][0]-insec[i][0])**2 + (p[a][1]-insec[i][1])**2);

        curint = i;

      }

    }

    pol.push([insec[curint][0], insec[curint][1]]); // store it to our polygon array

    print(pol);

    print(curint);

    //start looping through the points

    findPolygonLoop(c, s, mx, my, pol, insec, l1, curint);

    polygons.push(pol);

  }

  print(polygons);

}

​

function findLineIntersections(l1,c,s){

  let xint = [], yint = [];

  for(let l=0;l<c.length;l++){

    if(l!=l1 && c[l] != 'n/a'){

      xint[l] = ( (s[l] - s[l1]) / (c[l1] - c[l]) );

      yint[l] = (c[l1] * xint[l] + s[l1]);

    }

    else{

      xint[l] = 'n/a';

      yint[l] = 'n/a'

    }

  }

​

  //add intersections with borders in order T,B,L,R

  xint.push( (0 - s[l1])/c[l1], (height - s[l1])/c[l1], 0, width );

  yint.push(0, height, s[l1], c[l1] * width + s[l1]);

  let intersections = [];

  for(let i=0;i<xint.length;i++){

    intersections.push([xint[i], yint[i]])

  }

  return intersections;

}

​

function findPolygonLoop(c, s, mx, my, pol, insec, l1, curint){

  if(curint >= c.length){

    //its one of the borders

    insec = findBorderIntersections(curint - c.length, c, s);

  }

  else{

    //its with another line

    insec = findLineIntersections(curint, c, s);

  }

​

  //draw and print intersections

  drawIntersections(insec);

​

​

  //find closest intersection in the correct direction

  let closestInt;

  if(l1 == c.length || l1 == c.length + 1 || curint > c.length + 1){

    closestInt = findVertInt(Math.sign(my[curint] - pol[pol.length-1][1]), pol, insec, c);

  }

  // else if(curint > c.length + 1){

  //   closestInt = findVertInt(Math.sign(c[l1])*m[l1], pol, insec, c);

  // }

  else{

    closestInt = findHorInt(Math.sign(mx[curint] - pol[pol.length-1][0]), pol, insec);

  }

  if(pol[0][0] != closestInt[0][0] && pol[0][0] !=closestInt[0][1] ){

    l1 = curint;

    pol.push(closestInt[0]);

    curint = closestInt[1];

    findPolygonLoop(c, s, mx, my, pol, insec, l1, curint);

  }

​

  print(pol);

  print(curint);

}

​

function findBorderIntersections(b,c,s){

  if(b<2){

    //top or bottom

    let xint = [];

    for(let l=0;l<c.length;l++){

      if(c[l] != 'n/a'){

        xint[l] = (height*b - s[l])/c[l];

      }

      else{

        xint[l] = 'n/a';

      }

    }

    //add intersections with borders in order T,B,L,R

    xint.push( 'n/a', 'n/a', 0, width );

    let intersections = [];

    for(let i=0;i<xint.length;i++){

      if(xint[i] != 'n/a'){

        intersections.push([xint[i], height*b]);

      }

      else{

        intersections.push(['n/a','n/a']);

      }

    }

​

    return intersections;

  }

  else{

    //left or right

    let yint = [];

    for(let l=0;l<c.length;l++){

      if(c[l] != 'n/a'){

        yint[l] = width*(b-2)*c[l] + s[l];

      }

      else{

        yint[l] = 'n/a';

      }

    }

    //add intersections with borders in order T,B,L,R

    yint.push( 0, height, 'n/a', 'n/a' );

    let intersections = [];

    for(let i=0;i<yint.length;i++){

      if(yint[i] != 'n/a'){

        intersections.push([width*(b-2), yint[i]]);

      }

      else{

        intersections.push(['n/a','n/a']);

      }

    }

​

    return intersections;

  }

}

​

function findHorInt(ms, pol, insec){

  //use this one normally

  let curdist = sqrt(width**2 + height**2);

  let curint;

  for(let i=0; i<insec.length; i++){

    if(abs(pol[pol.length-1][0] - insec[i][0]) < curdist && 

       Math.sign(insec[i][0] - pol[pol.length-1][0]) == ms ){

      curdist = abs(pol[pol.length-1][0] - insec[i][0]);

      curint = i;

    }

  }

  return [[insec[curint][0], insec[curint][1]], curint];

}

​

function findVertInt(ms, pol, insec, c){

  //use this one if on a vertical borderline and/or if previous line was horizontal

  let curdist = sqrt(width**2 + height**2);

  let curint;

  for(let i=0; i<insec.length; i++){

    if(abs(pol[pol.length-1][1] - insec[i][1]) < curdist && 

       Math.sign(insec[i][1] - pol[pol.length-1][1]) == ms ){

      curdist = abs(pol[pol.length-1][1] - insec[i][1]);

      curint = i;

    }

  }

  return [[insec[curint][0], insec[curint][1]], curint];

}

​

​

function draw(){

  //draw using polygon arrays

  for(let i = 0; i<polygons.length; i++){

    fill(colors[i],255);

    beginShape()

    for(let j=0; j<polygons[i].length; j++){

      vertex(polygons[i][j][0], polygons[i][j][1])

    }

    endShape(CLOSE)

  }

}

​

function drawIntersections(insec){

  for(let i=0; i<insec.length; i++){

    if(insec[i][0] != 'n/a'){

      drawMarker(insec[i][0], insec[i][1], 150);

    }}

  print("intersections: " + insec);

}

​

function drawMarker(x, y, col) {

  stroke(col);

  line(x - markersize, y, x + markersize, y);

  line(x, y - markersize, x, y + markersize);

  noStroke();

}

​