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# redpirate

Member Since 14 May 2013
Offline Last Active Today, 08:12 PM

### Java Slick2D Terrain Generation

05 October 2013 - 08:55 PM

I am on the verge of finally making 2D terrain generation using simplex noise and I have all most of the code down except the world generates too randomly and has random floating islands. I want it to look like terraria and it is looking more like a top-down game. Here is the code for what I have so far:

```package main;

import org.newdawn.slick.AppGameContainer;
import org.newdawn.slick.BasicGame;
import org.newdawn.slick.Color;
import org.newdawn.slick.GameContainer;
import org.newdawn.slick.Graphics;
import org.newdawn.slick.SlickException;
import org.newdawn.slick.geom.Rectangle;

public class Game extends BasicGame
{
Rectangle[][] world = new Rectangle[15][15];
float[][] noise = new float[15][15];

public Game(String title)
{
super(title);
}

@Override
public void init(GameContainer gc) throws SlickException
{
Noise.seed();
float frequency = 1.0f / (float) world.length;

for (int x = 0; x < world.length; x++)
{
for (int y = 0; y < world[0].length; y++)
{
noise[x][y] = Noise.Generate((float) x * frequency, (float) y * frequency);
}
}

for (int x = 0; x < 15; x++)
{
for (int y = 0; y < 15; y++)
{
if (noise[x][y] < 0f)
world[x][y] = null;
if (noise[x][y] >= -0f) {
world[x][y] = new Rectangle(x * 32, y * 32, 32, 32);
}
}
}
}

@Override
public void render(GameContainer gc, Graphics g) throws SlickException
{
for (int x = 0; x < world.length; x++)
{
for (int y = 0; y < world[0].length; y++)
{
if (world[x][y] != null)
g.drawRect(world[x][y].getX(), world[x][y].getY(), world[x][y].getWidth(), world[x][y].getHeight());
}
}
}

@Override
public void update(GameContainer gc, int ticks) throws SlickException
{
// Nothing to update
}

public static void main(String[] args)
{
try
{
AppGameContainer game = new AppGameContainer(new Game("World Generator"));
game.setDisplayMode(1280, 720, false);
game.setTargetFrameRate(60);
game.setAlwaysRender(true);
game.start();
}

catch (SlickException e)
{
e.printStackTrace();
}
}

}

package main;

import java.util.Random;

public class Noise {
private static int[] perm = new int[] { 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 };

public static void seed()
{
Random rand = new Random();
for (int iter = 0; iter < perm.length; iter++)
{
perm[iter] = rand.nextInt(256);
}
}
// / <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)
{
final float F2 = 0.366025403f; // F2 = 0.5*(sqrt(3.0)-1.0)
final 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
final float F3 = 0.333333333f;
final 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);
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 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)
}

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);
}
}```

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