# Difference between revisions of "Heightmap"

A Heightmap class I wrote (more like edited Egon's random terrain)

Egon's Terrain script that randomly generates terrain heights.

```/**
* This is where the terrain-array is filled with some data, i.e. the
* terrain is build. Keep in mind that this approach to build a terrain
* is quite simple and slow. But it's easy to understand and the results
* are not that bad, so....
*/
for (int x = 0; x < X_SIZE; x++) {
for (int z = 0; z < Z_SIZE; z++) {
terrain[x][z] = -20 + (float) Math.random() * 40f; // Very
// simple....
}
}

/**
* We are now smoothing the terrain heights. This looks better because
* it removes sharp edges from the terrain.
*/
for (int x = 0; x < X_SIZE - 1; x++) {
for (int z = 0; z < Z_SIZE - 1; z++) {
terrain[x][z] = (terrain[x][z] + terrain[x + 1][z] + terrain[x][z + 1] + terrain[x + 1][z + 1]) / 4;
}
}

/**
* The terrain heights are calculated now. Now we have to build an
* Object3D from them.
*/
ground = new Object3D(X_SIZE * Z_SIZE * 2);

/**
* We have 50 tiles in x and z direction and 2 polygons per tile.
*/
float xSizeF = (float) X_SIZE;
float zSizeF = (float) Z_SIZE;

int id = texMan.getTextureID("base");

for (int x = 0; x < X_SIZE - 1; x++) {
for (int z = 0; z < Z_SIZE - 1; z++) {
/**
* We are now taking the heights calculated above and build the
* actual triangles using this data. The terrain's grid is fixed
* in x and z direction and so are the texture coordinates. The
* only part that varies is the height, represented by the data
* in terrain[][]. jPCT automatically takes care of vertex
* sharing and mesh optimizations (this is why building objects
* this way isn't blazing fast...but it pays out in the
* end...:-)) The Mesh is build with triangle strips in mind
* here. The format for these strips is equal to that of
* OpenGL's triangle strips.
*/

TextureInfo ti = new TextureInfo(id, (x / xSizeF), (z / zSizeF), ((x + 1) / xSizeF), (z / zSizeF), (x / xSizeF), ((z + 1) / zSizeF));
ground.addTriangle(new SimpleVector(x * 10, terrain[x][z], z * 10), new SimpleVector((x + 1) * 10, terrain[x + 1][z], z * 10),
new SimpleVector(x * 10, terrain[x][z + 1], (z + 1) * 10), ti);

ti = new TextureInfo(id, (x / xSizeF), ((z + 1) / zSizeF), ((x + 1) / xSizeF), (z / zSizeF), ((x + 1) / xSizeF), ((z + 1) / zSizeF));
ground.addTriangle(new SimpleVector(x * 10, terrain[x][z + 1], (z + 1) * 10), new SimpleVector((x + 1) * 10, terrain[x + 1][z], z * 10), new SimpleVector((x + 1) * 10,
terrain[x + 1][z + 1], (z + 1) * 10), ti);
}
}```

My terrain class that uses a bitmap.

When using it make sure you have a Texture Manager with a TextureID ready, (I used a flat gray 128x128 image for this)

```public class Terrain {

public static float HighestPoint = 0;

static Bitmap bmp = null;
static String pixel = null;
public static Object3D Generate(int X_SIZE, int Z_SIZE, TextureManager tm, String TextureID){

bmp = BitmapFactory.decodeResource(SpaceGrabber.resources, R.drawable.terrain); // the heightmap texture (128x128 due to memory limitations?)

float[][] terrain = new float[X_SIZE][Z_SIZE];

for (int x = 0; x < X_SIZE-1; x++) {
for (int z = 0; z < Z_SIZE-1; z++) {

pixel = Integer.toString(bmp.getPixel(x, z), 16);
terrain[x][z] = Integer.parseInt(pixel.charAt(1) + "" + pixel.charAt(2), 16);

if(terrain[x][z] > HighestPoint){
HighestPoint = terrain[x][z];
}
}

}
for (int x = 0; x < X_SIZE - 1; x++) {
for (int z = 0; z < Z_SIZE - 1; z++) {
terrain[x][z] = (terrain[x][z] + terrain[x + 1][z] + terrain[x][z + 1] + terrain[x + 1][z + 1]) / 4;
}
}
Object3D ground = new Object3D(X_SIZE * Z_SIZE * 2);

float xSizeF = (float) X_SIZE;
float zSizeF = (float) Z_SIZE;

int id = tm.getTextureID(TextureID); // I used a gray 128x128 texture

for (int x = 0; x < X_SIZE - 1; x++) {
for (int z = 0; z < Z_SIZE - 1; z++) {

TextureInfo ti = new TextureInfo(id, (x / xSizeF), (z / zSizeF), ((x + 1) / xSizeF), (z / zSizeF), (x / xSizeF), ((z + 1) / zSizeF));
ground.addTriangle(new SimpleVector(x * 10, terrain[x][z], z * 10), new SimpleVector((x + 1) * 10, terrain[x + 1][z], z * 10),
new SimpleVector(x * 10, terrain[x][z + 1], (z + 1) * 10), ti);

ti = new TextureInfo(id, (x / xSizeF), ((z + 1) / zSizeF), ((x + 1) / xSizeF), (z / zSizeF), ((x + 1) / xSizeF), ((z + 1) / zSizeF));
ground.addTriangle(new SimpleVector(x * 10, terrain[x][z + 1], (z + 1) * 10), new SimpleVector((x + 1) * 10, terrain[x + 1][z], z * 10), new SimpleVector((x + 1) * 10,
terrain[x + 1][z + 1], (z + 1) * 10), ti);
}
}

return ground;
}
}```

It might need some modification to work in your application, but it's something to start with :)

Kind regards, Kaiidyn.