# How do I generate believable terrain for a 2D game using cubes?

Ok, I have a fairly simple code that spawns a moving block. It spawns them in a range.

``````Instantiate (defaultground, Vector3 (transform.position.x, Random.Range(0,2.5), transform.position.z), transform.rotation);
``````

What I want to do with this snippet code is to replace it with code that can set a “trend”, ie. instead of randomly making blocks, making it go up and down in hills. How should I approach this?

Check out this:

Basically, you can generate Perlin noise, and use that to drive the vertical position of your cubes.

I am not sure what you want to do—is using Unity’s terrain system an option? There are also plug-ins for generating procedural landscape.

Edit:
Here is an version from the DevMag article translated to Unity to get you started. It is 1D only… read the article for an explanation.

Here is how it looks:

![alt text][1]

…Sorry, QATO’s image thing does not want to work… here is the link:

``````public class TerrainSpawn : MonoBehaviour
{
public GameObject cubePrefab;
public int cubesToGenerate = 20;

float[] GetEmptyArray(int width)
{
return new float[width];
}

float[] GenerateWhiteNoise(int width)
{
float[] noise = GetEmptyArray(width);

for (int i = 0; i < width; i++)
{
noise *= (float)Random.value;*
``````

}

return noise;
}

float Interpolate(float x0, float x1, float alpha)
{
return x0 * (1 - alpha) + alpha * x1;
}

float[] GenerateSmoothNoise(float[] baseNoise, int octave)
{
int width = baseNoise.Length;
float[] smoothNoise = GetEmptyArray(width);
int samplePeriod = 1 << octave; // calculates 2 ^ k
float sampleFrequency = 1.0f / samplePeriod;

for (int i = 0; i < width; i++)
{
//calculate the horizontal sampling indices
int sample_i0 = (i / samplePeriod) * samplePeriod;
int sample_i1 = (sample_i0 + samplePeriod) % width; //wrap around
float horizontal_blend = (i - sample_i0) * sampleFrequency;

smoothNoise = Interpolate(baseNoise[sample_i0],
baseNoise[sample_i1], horizontal_blend);
}

return smoothNoise;
}

float[] GeneratePerlinNoise(float[] baseNoise, int octaveCount)
{
int width = baseNoise.Length;
float[][] smoothNoise = new float[octaveCount][]; //an array of 2D arrays containing
float persistance = 0.5f;

//generate smooth noise
for (int i = 0; i < octaveCount; i++)
{
smoothNoise = GenerateSmoothNoise(baseNoise, i);
}

float[] perlinNoise = GetEmptyArray(width);
float amplitude = 1.0f;
float totalAmplitude = 0.0f;

//blend noise together
for (int octave = octaveCount - 1; octave >= 0; octave–)
{
amplitude *= persistance;
totalAmplitude += amplitude;

for (int i = 0; i < width; i++)
{
perlinNoise += smoothNoise[octave] * amplitude;
}
}

//normalisation
for (int i = 0; i < width; i++)
{
perlinNoise /= totalAmplitude;
}

return perlinNoise;
}

public void Start()
{
float[] perlinNoise = GeneratePerlinNoise(GenerateWhiteNoise(cubesToGenerate), 5);

for (int i = 0; i < cubesToGenerate; i++)
{
GameObject gObject = (GameObject) Instantiate(cubePrefab);

gObject.transform.position = new Vector3(i, 4perlinNoise, 0);*
}
}
}
[1]: http://www.devmag.org.za/examples/perlin_noise/terrain.png