int w = 800;
int h = 600;
int z = 600;
color white = color(255, 255, 255);
color black = color(0, 0, 0);
color red = color(255, 0, 0);
color green = color(0, 255, 0);
color blue = color(0, 0, 255);
color yellow = color(255,255,0);

ArrayList<ArrayList<PVector>> container;

void setup() {
  size(w, h, P2D);
  background(0);
  smooth();
  frameRate(30);
  resetTriangles();

}

void resetTriangles() {
  container = new ArrayList<ArrayList<PVector>>();
  container.add(randomTriangle());
  container.add(randomTriangle());
  print("------------------------\n");
  testIntersect(container.get(0), container.get(1));
  print("-------------------------\n");

}

void draw() {
  background(0);
  noFill();

  stroke(green);
  triangle(int(container.get(0).get(0).get().x),int(container.get(0).get(0).get().y),
           int(container.get(0).get(1).get().x),int(container.get(0).get(1).get().y),
           int(container.get(0).get(2).get().x),int(container.get(0).get(2).get().y));

  stroke(color(255,0,255));
  triangle(int(container.get(1).get(0).get().x),int(container.get(1).get(0).get().y),
           int(container.get(1).get(1).get().x),int(container.get(1).get(1).get().y),
           int(container.get(1).get(2).get().x),int(container.get(1).get(2).get().y));

}



void mousePressed() {
  resetTriangles();
}

ArrayList randomTriangle() {
  ArrayList<PVector> rt = new ArrayList<PVector>();
  for (int i = 0; i < 3; i++) {
    rt.add(new PVector(int(random(w)), int(random(h))));
  }
  return rt;
}

boolean testIntersect(ArrayList<PVector> a, ArrayList<PVector> b) {
  PVector[] n = new PVector[6];
  n[0] = PVector.sub(a.get(1), a.get(0));
  n[1] = PVector.sub(a.get(2), a.get(1));
  n[2] = PVector.sub(a.get(0), a.get(2));

  n[3] = PVector.sub(b.get(1), b.get(0));
  n[4] = PVector.sub(b.get(2), b.get(1));
  n[5] = PVector.sub(b.get(0), b.get(2));

  float[][] a_dots = new float[6][3];
  float[][] b_dots = new float[6][3];

  for (int i = 0; i < 6; i++) {
    for (int j = 0; j < 3; j++) {
      a_dots[i][j] = n[i].dot(a.get(j));
      b_dots[i][j] = n[i].dot(b.get(j));
    }
  }

  for (int i = 0; i < 6; i++) {
    float as = a_dots[i][0];
    float al = a_dots[i][0];
    float bs = b_dots[i][0];
    float bl = b_dots[i][0];

    for (int j = 1; j < 3; j++) {
      if (a_dots[i][j] < as) { as = a_dots[i][j]; }
      if (a_dots[i][j] > al) { al = a_dots[i][j]; }
      if (b_dots[i][j] < bs) { bs = b_dots[i][j]; }
      if (b_dots[i][j] > bl) { bl = b_dots[i][j]; }
    }
    print ("as: "+as+" al: "+al+" bs: "+bs+" bl: "+bl+" -- ");
    if ((as < bs && al > bs) || (bs < as && bl > as)) {
      print(1);
    } else {
      print(0);
    }
    print ("\n");
  /*
    AS BS AL BL
    BS AS AL BL
  */
  }
  print("\n");
  return true;
}