[NO PROBLEM FROM THE START, DELETE THIS PLZ] Simplex Noise Repeating

I got this code for simplex noise somewhere on the internet and I have no idea how it works. Ye I know I shouldn’t be copying code, but it is really much faster than my perlin noise.
The problem is that when I generate my terrain, it seems that this code only generates a few different terrains. I haven’t tried counting, but I would go for 10+

Maybe you could help me here, because I’m lost in this code :smiley:
Also, maybe there is a perlin/simplex noise library out there? :stuck_out_tongue:

public class SimplexNoise {  // Simplex noise in 2D, 3D and 4D

	  public static int RANDOMSEED=-1;
	  private static int NUMBEROFSWAPS=400;  

	  private static Grad grad3[] = {new Grad(1,1,0),new Grad(-1,1,0),new Grad(1,-1,0),new Grad(-1,-1,0),
	                                 new Grad(1,0,1),new Grad(-1,0,1),new Grad(1,0,-1),new Grad(-1,0,-1),
	                                 new Grad(0,1,1),new Grad(0,-1,1),new Grad(0,1,-1),new Grad(0,-1,-1)};

	  private static short p_supply[] = {151,160,137,91,90,15, //this contains all the numbers between 0 and 255, these are put in a random order depending upon the seed
	  131,13,201,95,96,53,194,233,7,225,140,36,103,30,69,142,8,99,37,240,21,10,23,
	  190, 6,148,247,120,234,75,0,26,197,62,94,252,219,203,117,35,11,32,57,177,33,
	  88,237,149,56,87,174,20,125,136,171,168, 68,175,74,165,71,134,139,48,27,166,
	  77,146,158,231,83,111,229,122,60,211,133,230,220,105,92,41,55,46,245,40,244,
	  102,143,54, 65,25,63,161, 1,216,80,73,209,76,132,187,208, 89,18,169,200,196,
	  135,130,116,188,159,86,164,100,109,198,173,186, 3,64,52,217,226,250,124,123,
	  5,202,38,147,118,126,255,82,85,212,207,206,59,227,47,16,58,17,182,189,28,42,
	  223,183,170,213,119,248,152, 2,44,154,163, 70,221,153,101,155,167, 43,172,9,
	  129,22,39,253, 19,98,108,110,79,113,224,232,178,185, 112,104,218,246,97,228,
	  251,34,242,193,238,210,144,12,191,179,162,241, 81,51,145,235,249,14,239,107,
	  49,192,214, 31,181,199,106,157,184, 84,204,176,115,121,50,45,127, 4,150,254,
	  138,236,205,93,222,114,67,29,24,72,243,141,128,195,78,66,215,61,156,180};

	  private short p[]=new short[p_supply.length];

	  // To remove the need for index wrapping, double the permutation table length
	  private short perm[] = new short[512];
	  private short permMod12[] = new short[512];
	  
	  public float div = 45;
	  
	  public SimplexNoise() {
		  this(RANDOMSEED);
	  }
	  
	  public SimplexNoise(int seed) {
		
	    p=p_supply.clone();
	        
	    if (seed==RANDOMSEED){
	        Random rand=new Random();
	        seed=rand.nextInt();
	    }

	    //the random for the swaps
	    Random rand=new Random(seed);

	    //the seed determines the swaps that occur between the default order and the order we're actually going to use
	    for(int i=0;i<NUMBEROFSWAPS;i++){
	        int swapFrom=rand.nextInt(p.length);
	        int swapTo=rand.nextInt(p.length);

	        short temp=p[swapFrom];
	        p[swapFrom]=p[swapTo];
	        p[swapTo]=temp;
	    }


	    for(int i=0; i<512; i++)
	    {
	      perm[i]=p[i & 255];
	      permMod12[i] = (short)(perm[i] % 12);
	    }
	  }

	  // Skewing and unskewing factors for 2, 3, and 4 dimensions
	  private static final double F2 = 0.5*(Math.sqrt(3.0)-1.0);
	  private static final double G2 = (3.0-Math.sqrt(3.0))/6.0;

	  // This method is a *lot* faster than using (int)Math.floor(x)
	  private static int fastfloor(double x) {
	    int xi = (int)x;
	    return x<xi ? xi-1 : xi;
	  }

	  private static double dot(Grad g, double x, double y) {
	    return g.x*x + g.y*y; }


	  // 2D simplex noise
	  public float noise(float xin, float yin) {
		  
		  xin/=div;
		  yin/=div;
		  
	    double n0, n1, n2; // Noise contributions from the three corners
	    // Skew the input space to determine which simplex cell we're in
	    double s = (xin+yin)*F2; // Hairy factor for 2D
	    int i = fastfloor(xin+s);
	    int j = fastfloor(yin+s);
	    double t = (i+j)*G2;
	    double X0 = i-t; // Unskew the cell origin back to (x,y) space
	    double Y0 = j-t;
	    double x0 = xin-X0; // The x,y distances from the cell origin
	    double y0 = yin-Y0;
	    // For the 2D case, the simplex shape is an equilateral triangle.
	    // Determine which simplex we are in.
	    int i1, j1; // Offsets for second (middle) corner of simplex in (i,j) coords
	    if(x0>y0) {i1=1; j1=0;} // lower triangle, XY order: (0,0)->(1,0)->(1,1)
	    else {i1=0; j1=1;}      // upper triangle, YX order: (0,0)->(0,1)->(1,1)
	    // A step of (1,0) in (i,j) means a step of (1-c,-c) in (x,y), and
	    // a step of (0,1) in (i,j) means a step of (-c,1-c) in (x,y), where
	    // c = (3-sqrt(3))/6
	    double x1 = x0 - i1 + G2; // Offsets for middle corner in (x,y) unskewed coords
	    double y1 = y0 - j1 + G2;
	    double x2 = x0 - 1.0 + 2.0 * G2; // Offsets for last corner in (x,y) unskewed coords
	    double y2 = y0 - 1.0 + 2.0 * G2;
	    // Work out the hashed gradient indices of the three simplex corners
	    int ii = i & 255;
	    int jj = j & 255;
	    int gi0 = permMod12[ii+perm[jj]];
	    int gi1 = permMod12[ii+i1+perm[jj+j1]];
	    int gi2 = permMod12[ii+1+perm[jj+1]];
	    // Calculate the contribution from the three corners
	    double t0 = 0.5 - x0*x0-y0*y0;
	    if(t0<0) n0 = 0.0;
	    else {
	      t0 *= t0;
	      n0 = t0 * t0 * dot(grad3[gi0], x0, y0);  // (x,y) of grad3 used for 2D gradient
	    }
	    double t1 = 0.5 - x1*x1-y1*y1;
	    if(t1<0) n1 = 0.0;
	    else {
	      t1 *= t1;
	      n1 = t1 * t1 * dot(grad3[gi1], x1, y1);
	    }
	    double t2 = 0.5 - x2*x2-y2*y2;
	    if(t2<0) n2 = 0.0;
	    else {
	      t2 *= t2;
	      n2 = t2 * t2 * dot(grad3[gi2], x2, y2);
	    }

	    
	    
	    // Add contributions from each corner to get the final noise value.
	    // The result is scaled to return values in the interval [-1,1].
	    return (float) (70.0 * (n0 + n1 + n2));
	  }



	  // Inner class to speed upp gradient computations
	  // (array access is a lot slower than member access)
	  private static class Grad
	  {
	    double x, y;

	    Grad(double x, double y, double z)
	    {
	      this.x = x;
	      this.y = y;
	    }

	  }

	}