Java 2D Side-View Terrain Generation

Question

I am trying to create a game with a Terraria like feel and I have browsed many threads/forums and can't seem to get anything working for myself. I've chosen the Simplex Noise algorithm to try and generate a side view game like Terraria but it's just a jumbled mess. I was wondering if someone could help me make a terrain generator using a Simplex Noise class I found online? I have blocks that are 32x32 that I want to spawn in for the terrain and then some I want at certain depths, etc. I'll post the code to the class below. I'm just starting with this random generation stuff and it is quite tricky for me.

import java.util.Random;

public class SimplexNoise {

    private static int grad3[][] = { {1,1,0},{-1,1,0},{1,-1,0},{-1,-1,0},
                                    {1,0,1},{-1,0,1},{1,0,-1},{-1,0,-1},
                                    {0,1,1},{0,-1,1},{0,1,-1},{0,-1,-1}};

    private static int p[] = { 151,160,137,91,90,15,
                            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};

    // To remove the need for index wrapping, double the permutation table length
    private static int perm[] = new int[512];
    static { 
        for(int i = 0; i < 512; i++) 
            perm[i] = p[i & 255]; 
    }

    // This method is a *lot* faster than using (int)Math.floor(x)
    private static int fastfloor(double x) {
        return x > 0 ? (int)x : (int)x - 1;
    }

    private static double dot(int g[], double x, double y) {
        return g[0] * x + g[1] * y; 
    }

    // 2D simplex noise
    public static double noise(double xin, double yin) {
        double n0, n1, n2;

        final double F2 = 0.5 * (Math.sqrt(3.0) - 1.0);
        double s = (xin + yin) * F2;
        int i = fastfloor(xin + s);
        int j = fastfloor(yin + s);

        final double G2 = (3.0 - Math.sqrt(3.0)) / 6.0;
        double t = (i + j) * G2;
        double X0 = i - t;
        double Y0 = j - t;
        double x0 = xin - X0;
        double y0 = yin - Y0;

        int i1, j1;
        if (x0 > y0) {
            i1=1; 
            j1=0;
        } else {
            i1 = 0;
            j1 = 1;
        }

        double x1 = x0 - i1 + G2;
        double y1 = y0 - j1 + G2;
        double x2 = x0 - 1.0 + 2.0 * G2;
        double y2 = y0 - 1.0 + 2.0 * G2;

        int ii = i & 255;
        int jj = j & 255;
        int gi0 = perm[ii + perm[jj]] % 12;
        int gi1 = perm[ii + i1 + perm[jj + j1]] % 12;
        int gi2 = perm[ii + 1 + perm[jj + 1]] % 12;

        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);
        }

        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);
        }

        return 70.0 * (n0 + n1 + n2);
    }

    public static void genGrad(long seed) {
        Random rnd = new Random(seed);
        for(int i = 0; i < 255; i++)
          p[i] = i;
        for(int i = 0; i < 255; i++) {
          int j = rnd.nextInt(255);
          int nSwap = p[i];
          p[i]  = p[j];
          p[j]  = nSwap;
        }

        for(int i = 0; i < 512; i++) 
            perm[i] = p[i & 255];
    }

}

Here is the new code I'm using and it prints out all the blocks at the same location:

Block[][] chunk = new Block[Chunk.CHUNK_WIDTH_BLOCKS][Chunk.CHUNK_HEIGHT_BLOCKS];
    float[][] positions = new float[Chunk.CHUNK_WIDTH_BLOCKS][Chunk.CHUNK_HEIGHT_BLOCKS];
    float frequency = 1.0f / (float) chunk.length; 

    for (int x = 0; x < chunk.length - 1; x++) 
    { 
        for (int y = 0; y < chunk[x].length - 1; y++) 
        { 
            positions[x][y] = SimplexNoise.Generate((float) x * frequency, (float) y * frequency);
            g.drawRect(positions[x][0], positions[0][y], Block.BLOCK_WIDTH, Block.BLOCK_HEIGHT);
        } 
    } 

    for (int x = 0; x < Chunk.CHUNK_WIDTH_BLOCKS; x++)
    {
        for (int y = 0; y < Chunk.CHUNK_HEIGHT_BLOCKS; y++)
        {
            if (positions[x][y] < 0f)
                chunk[x][y] = new Block();
            if (positions[x][y] >= -0f)
                chunk[x][y] = new Block();
        }
    }

Answer 1

I just found this LINK to explain how to use Perlin noise in 2d terrain generation like terraria.

Here is the code for the noise class:

public class Noise
    {
        /// <summary>
        /// 1D simplex noise
        /// </summary>
        /// <param name="x"></param>
        /// <returns></returns>
        public static float Generate(float x)
        {
            int i0 = FastFloor(x);
            int i1 = i0 + 1;
            float x0 = x - i0;
            float x1 = x0 - 1.0f;
            float n0, n1;
            float t0 = 1.0f - x0 * x0;
            t0 *= t0;
            n0 = t0 * t0 * grad(perm[i0 & 0xff], x0);
            float t1 = 1.0f - x1 * x1;
            t1 *= t1;
            n1 = t1 * t1 * grad(perm[i1 & 0xff], x1);
            // The maximum value of this noise is 8*(3/4)^4 = 2.53125
            // A factor of 0.395 scales to fit exactly within [-1,1]
            return 0.395f * (n0 + n1);
        }
        /// <summary>
        /// 2D simplex noise
        /// </summary>
        /// <param name="x"></param>
        /// <param name="y"></param>
        /// <returns></returns>
        public static float Generate(float x, float y)
        {
            const float F2 = 0.366025403f; // F2 = 0.5*(sqrt(3.0)-1.0)
            const float G2 = 0.211324865f; // G2 = (3.0-Math.sqrt(3.0))/6.0
            float n0, n1, n2; // Noise contributions from the three corners
            // Skew the input space to determine which simplex cell we're in
            float s = (x + y) * F2; // Hairy factor for 2D
            float xs = x + s;
            float ys = y + s;
            int i = FastFloor(xs);
            int j = FastFloor(ys);
            float t = (float)(i + j) * G2;
            float X0 = i - t; // Unskew the cell origin back to (x,y) space
            float Y0 = j - t;
            float x0 = x - X0; // The x,y distances from the cell origin
            float y0 = y - 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
            float x1 = x0 - i1 + G2; // Offsets for middle corner in (x,y) unskewed coords
            float y1 = y0 - j1 + G2;
            float x2 = x0 - 1.0f + 2.0f * G2; // Offsets for last corner in (x,y) unskewed coords
            float y2 = y0 - 1.0f + 2.0f * G2;
            // Wrap the integer indices at 256, to avoid indexing perm[] out of bounds
            int ii = i % 256;
            int jj = j % 256;
            // Calculate the contribution from the three corners
            float t0 = 0.5f - x0 * x0 - y0 * y0;
            if (t0 < 0.0f) n0 = 0.0f;
            else
            {
                t0 *= t0;
                n0 = t0 * t0 * grad(perm[ii + perm[jj]], x0, y0);
            }
            float t1 = 0.5f - x1 * x1 - y1 * y1;
            if (t1 < 0.0f) n1 = 0.0f;
            else
            {
                t1 *= t1;
                n1 = t1 * t1 * grad(perm[ii + i1 + perm[jj + j1]], x1, y1);
            }
            float t2 = 0.5f - x2 * x2 - y2 * y2;
            if (t2 < 0.0f) n2 = 0.0f;
            else
            {
                t2 *= t2;
                n2 = t2 * t2 * grad(perm[ii + 1 + perm[jj + 1]], 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 40.0f * (n0 + n1 + n2); // TODO: The scale factor is preliminary!
        }

        public static float Generate(float x, float y, float z)
        {
            // Simple skewing factors for the 3D case
            const float F3 = 0.333333333f;
            const float G3 = 0.166666667f;
            float n0, n1, n2, n3; // Noise contributions from the four corners
            // Skew the input space to determine which simplex cell we're in
            float s = (x + y + z) * F3; // Very nice and simple skew factor for 3D
            float xs = x + s;
            float ys = y + s;
            float zs = z + s;
            int i = FastFloor(xs);
            int j = FastFloor(ys);[attachment=11149:perlinBug.png]
            int k = FastFloor(zs);
            float t = (float)(i + j + k) * G3;
            float X0 = i - t; // Unskew the cell origin back to (x,y,z) space
            float Y0 = j - t;
            float Z0 = k - t;
            float x0 = x - X0; // The x,y,z distances from the cell origin
            float y0 = y - Y0;
            float z0 = z - Z0;
            // For the 3D case, the simplex shape is a slightly irregular tetrahedron.
            // Determine which simplex we are in.
            int i1, j1, k1; // Offsets for second corner of simplex in (i,j,k) coords
            int i2, j2, k2; // Offsets for third corner of simplex in (i,j,k) coords
            /* This code would benefit from a backport from the GLSL version! */
            if (x0 >= y0)
            {
                if (y0 >= z0)
                { i1 = 1; j1 = 0; k1 = 0; i2 = 1; j2 = 1; k2 = 0; } // X Y Z order
                else if (x0 >= z0) { i1 = 1; j1 = 0; k1 = 0; i2 = 1; j2 = 0; k2 = 1; } // X Z Y order
                else { i1 = 0; j1 = 0; k1 = 1; i2 = 1; j2 = 0; k2 = 1; } // Z X Y order
            }
            else
            { // x0<y0
                if (y0 < z0) { i1 = 0; j1 = 0; k1 = 1; i2 = 0; j2 = 1; k2 = 1; } // Z Y X order
                else if (x0 < z0) { i1 = 0; j1 = 1; k1 = 0; i2 = 0; j2 = 1; k2 = 1; } // Y Z X order
                else { i1 = 0; j1 = 1; k1 = 0; i2 = 1; j2 = 1; k2 = 0; } // Y X Z order
            }
            // A step of (1,0,0) in (i,j,k) means a step of (1-c,-c,-c) in (x,y,z),
            // a step of (0,1,0) in (i,j,k) means a step of (-c,1-c,-c) in (x,y,z), and
            // a step of (0,0,1) in (i,j,k) means a step of (-c,-c,1-c) in (x,y,z), where
            // c = 1/6.
            float x1 = x0 - i1 + G3; // Offsets for second corner in (x,y,z) coords
            float y1 = y0 - j1 + G3;
            float z1 = z0 - k1 + G3;
            float x2 = x0 - i2 + 2.0f * G3; // Offsets for third corner in (x,y,z) coords
            float y2 = y0 - j2 + 2.0f * G3;
            float z2 = z0 - k2 + 2.0f * G3;
            float x3 = x0 - 1.0f + 3.0f * G3; // Offsets for last corner in (x,y,z) coords
            float y3 = y0 - 1.0f + 3.0f * G3;
            float z3 = z0 - 1.0f + 3.0f * G3;
            // Wrap the integer indices at 256, to avoid indexing perm[] out of bounds
            int ii = i % 256;
            int jj = j % 256;
            int kk = k % 256;
            // Calculate the contribution from the four corners
            float t0 = 0.6f - x0 * x0 - y0 * y0 - z0 * z0;
            if (t0 < 0.0f) n0 = 0.0f;
            else
            {
                t0 *= t0;
                n0 = t0 * t0 * grad(perm[ii + perm[jj + perm[kk]]], x0, y0, z0);
            }
            float t1 = 0.6f - x1 * x1 - y1 * y1 - z1 * z1;
            if (t1 < 0.0f) n1 = 0.0f;
            else
            {
                t1 *= t1;
                n1 = t1 * t1 * grad(perm[ii + i1 + perm[jj + j1 + perm[kk + k1]]], x1, y1, z1);
            }
            float t2 = 0.6f - x2 * x2 - y2 * y2 - z2 * z2;
            if (t2 < 0.0f) n2 = 0.0f;
            else
            {
                t2 *= t2;
                n2 = t2 * t2 * grad(perm[ii + i2 + perm[jj + j2 + perm[kk + k2]]], x2, y2, z2);
            }
            float t3 = 0.6f - x3 * x3 - y3 * y3 - z3 * z3;
            if (t3 < 0.0f) n3 = 0.0f;
            else
            {
                t3 *= t3;
                n3 = t3 * t3 * grad(perm[ii + 1 + perm[jj + 1 + perm[kk + 1]]], x3, y3, z3);
            }
            // Add contributions from each corner to get the final noise value.
            // The result is scaled to stay just inside [-1,1]
            return 32.0f * (n0 + n1 + n2 + n3); // TODO: The scale factor is preliminary!
        }
        private static byte[] perm = new byte[512] { 151,160,137,91,90,15,
              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,
              151,160,137,91,90,15,
              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 static int FastFloor(float x)
        {
            return (x > 0) ? ((int)x) : (((int)x) - 1);
        }
        private static float grad(int hash, float x)
        {
            int h = hash & 15;
            float grad = 1.0f + (h & 7);   // Gradient value 1.0, 2.0, ..., 8.0
            if ((h & 8) != 0) grad = -grad;      // Set a random sign for the gradient
            return (grad * x);         // Multiply the gradient with the distance
        }
        private static float grad(int hash, float x, float y)
        {
            int h = hash & 7;     // Convert low 3 bits of hash code
            float u = h < 4 ? x : y;  // into 8 simple gradient directions,
            float v = h < 4 ? y : x;  // and compute the dot product with (x,y).
            return ((h & 1) != 0 ? -u : u) + ((h & 2) != 0 ? -2.0f * v : 2.0f * v);
        }
        private static float grad(int hash, float x, float y, float z)
        {
            int h = hash & 15;   // Convert low 4 bits of hash code into 12 simple
            float u = h < 8 ? x : y; // gradient directions, and compute dot product.
            float v = h < 4 ? y : h == 12 || h == 14 ? x : z; // Fix repeats at h = 12 to 15
            return ((h & 1) != 0 ? -u : u) + ((h & 2) != 0 ? -v : v);
        }
        private static float grad(int hash, float x, float y, float z, float t)
        {
            int h = hash & 31;    // Convert low 5 bits of hash code into 32 simple
            float u = h < 24 ? x : y; // gradient directions, and compute dot product.
            float v = h < 16 ? y : z;
            float w = h < 8 ? z : t;
            return ((h & 1) != 0 ? -u : u) + ((h & 2) != 0 ? -v : v) + ((h & 4) != 0 ? -w : w);
 }
}

The way that he uses it is like so:

private void CreatePerlinWorld()
        {
            world = new Tile[_maxWidth, _maxHeight];
            diamond = new float[_maxWidth, _maxHeight];
            for (int x = 0; x < world.GetLength(0) - 1; x++)
            {
                for (int y = 0; y < world.GetLength(1) - 1; y++)
                {
                    diamond[x,y] = Noise.Generate(x, y);
                }
            }
        }
        private void GeneratePerlinWorld()
        {
            for (int x = 0; x < _maxWidth; x++)
            {
                for (int y = 0; y < _maxHeight; y++)
                {
                    if (diamond[x, y] < 0f)
                        world[x, y] = new Tile(TileType.None, TileCollision.Passable, ToolType.None);
                    if (diamond[x, y] >= -0f)
                        world[x, y] = new Tile(TileType.Dirt, TileCollision.Impassable, ToolType.Pickaxe);
                }
            }
        }