int[][] p = new int[5001][4];
int a = 0;
int[][] knot = new int[500][4];
int k = 1;



void setup() {
  size(500,500,P3D);
  calcP();
}


void draw()
{
  
  //APPLY A TRANSFORMATION SUCH THAT THE SCENE IS 'CENTERED' (point[0,0,0] is at the middle of the window)
  translate(width/2, height/2, 0);
  //EVERYTIME THE draw() FUNCTION IS CALLED, ROTATES EVERYTHING BY AN INCREASING AMOUNT 'a'
  rotateY(radians(a));
  a++;

  //CLEAR EVERYTHING
  background(200);

 /* Draw a yellow box at the center of the 'world'... useful only for debug
  fill(255,255,0);
  box(100);
  /*


  /* This part is to plot all the points present in the array p[][]
    for(int i = 1; i< 4000; i++)
   {
   point(p[i][1], p[i][2], p[i][3]);
   }
   */

  //DRAWS A SHAPE MADE OF CONNECTED LINES WITH VERTICES CORRESPONDING TO THE KNOTS (knot[][])
  beginShape(LINES);
  for(int i = 1; i <= k-1; i++)
  {
    vertex(knot[i][1], knot[i][2], knot[i][3]);
    vertex(knot[i+1][1], knot[i+1][2], knot[i+1][3]);
  }
  endShape();



}

void calcP()
{
  int dirX, dirY, dirZ, sgmSteps, dirXold, dirYold, dirZold;
  int posX, posY, posZ;
  posX = posY = posZ = sgmSteps = dirX = dirY = dirZ = dirXold = dirYold = dirZold = 0;

  for(int i = 1; i< 5000; i++) //Each loop calculates one point and puts the coordinates to an array with the points previously calculated
  {
    
    //WHEN THE SEGMENT HAS BEEN COMPLETED (sgmSteps == 0) CALCULATE A NEW KNOT WITH A DIFFERENT SET OF DIRECTIONS (X,Y,Z) AND SEGMENT LENGTH (steps)
    if(sgmSteps == 0)
    {
	dirXold = dirX;
	dirYold = dirY;
	dirZold = dirZ;

	sgmSteps = round(random(10,100));

	while(dirX == dirXold && dirY == dirYold && dirZ == dirZold || dirX == -dirXold && dirY == -dirYold && dirZ == -dirZold)
	{
	  dirX = round(pow(-1, round(random(1,2))));
	  dirY = round(pow(-1, round(random(1,2))));
	  dirZ = round(pow(-1, round(random(1,2))));
	}

	if(dirX == dirXold && dirY == dirYold && dirZ == dirZold || dirX == -dirXold && dirY == -dirYold && dirZ == -dirZold)
	{ 
	  println("DUPLICATE");
	}

	println("-- NEW KNOT --");
	println(dirX + " | " + dirY + " | " + dirZ);
	knot[k][1] = posX;
	knot[k][2] = posY;
	knot[k][3] = posZ;
	k++;
    }
    /////////////////////////////////////////////////////////////////////////////////

    //NEW POINT POSITION
    posX = posX + dirX;
    posY = posY + dirY;
    posZ = posZ + dirZ;

    //SERIES OF CHECKINGS TO SEE IT THE NEW POINT GOES BEYOND THE SCREEN BOUNDRAIS
    if(posX >= width/2 -1 | posX <= -width/2 +1)
    {
	dirX = -1 * dirX;
	println("-- NEW KNOT --");
	println(dirX + " | " + dirY + " | " + dirZ);
	knot[k][1] = posX;
	knot[k][2] = posY;
	knot[k][3] = posZ;
	k++;
    }

    if(posY >= height/2 -1| posY <= -height/2 +1)
    {
	dirY = -1 * dirY;
	println("-- NEW KNOT --");
	println(dirX + " | " + dirY + " | " + dirZ);
	knot[k][1] = posX;
	knot[k][2] = posY;
	knot[k][3] = posZ;
	k++;
    }


    if(posZ >= width/2 | posZ <= -width/2)
    {
	posZ = -1 * posZ;
	println("-- NEW KNOT --");
	println(dirX + " | " + dirY + " | " + dirZ);
	knot[k][1] = posX;
	knot[k][2] = posY;
	knot[k][3] = posZ;
	k++;
    }
    /////////////////////////////////////////////////////////////////////////////////

    sgmSteps--; //decreases the length of the current segment because one more 'point' has been calculated  

    //ADDS THE POINT CALCULATED TO THE ARRAY CONTAING ALL THE POINTS (p[][])
    p[i][1] = posX;
    p[i][2] = posY;
    p[i][3] = posZ;
  }
}