Noise

Perlin.cs

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class Perlin : MonoBehaviour {

	// Use this for initialization
	void Start () {

		GameObject obj = GameObject.Find("Terrain");
 
        if (obj.GetComponent<Terrain>())
        {
            Terrain terrain = obj.GetComponent<Terrain>();
			float[,] heights = new float[terrain.terrainData.heightmapWidth, terrain.terrainData.heightmapHeight];

			float tileSize = 10.0f;
			print(terrain.terrainData.heightmapWidth);
			print(terrain.terrainData.heightmapHeight);
			for (int i = 0; i < terrain.terrainData.heightmapWidth; i++)
			{
				for (int k = 0; k < terrain.terrainData.heightmapHeight; k++)
				{
					float x = ((float)i / (float)terrain.terrainData.heightmapWidth) * tileSize;
					float y = ((float)k / (float)terrain.terrainData.heightmapHeight) * tileSize;
					// print(x);
					// print(y);
					float h = (PerlinNoise.getHeight(x, y) + 1) / 10.0f;

					heights[i, k] = h;
				}
			}
 
        	terrain.terrainData.SetHeights(0, 0, heights);
        }

		
	}
	
	// Update is called once per frame
	void Update () {
		
	}
}

PerlinNoise.cs

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class PerlinNoise {


    public static float getHeight(float x, float z){
        int lowerX = (int)Mathf.Floor(x);
        int lowerZ = (int)Mathf.Floor(z);
        int upperX = lowerX + 1;
        int upperZ = lowerZ + 1;
        float offsetX = x - lowerX;
        float offsetZ = z - lowerZ;

        float lowerLeftGrad = Vector2.Dot(new Vector2(offsetX, offsetZ), getCornerVector(lowerX, lowerZ));
        float upperLeftGrad = Vector2.Dot(new Vector2(offsetX, offsetZ - 1), getCornerVector(lowerX, lowerZ + 1));
        float upperRightGrad = Vector2.Dot(new Vector2(offsetX - 1, offsetZ - 1), getCornerVector(lowerX + 1, lowerZ + 1));
        float lowerRightGrad = Vector2.Dot(new Vector2(offsetX - 1, offsetZ), getCornerVector(lowerX + 1, lowerZ));

        float lowerLerp = lerp(lowerLeftGrad, lowerRightGrad, fade(offsetX));
        float upperLerp = lerp(upperLeftGrad, upperRightGrad, fade(offsetX));
        float totalLerp = lerp(lowerLerp, upperLerp, fade(offsetZ));
        return totalLerp;
    }

    public static float fade(float t){
        return t * t * t * (t * (t * 6 - 15) + 10);
    }

    public static float lerp(float u, float v, float time){
        return u * (1 - time) + v * time;
    }

    public static Vector2 getCornerVector(int x, int y){
        int seed = (x ^ (x >> 16)) << 16 | ((y ^ (y >> 16)) & 0xFFFF);
        Random.seed = seed;
        Vector2 corner = new Vector2(Random.Range(-1.0f, 1.0f), Random.Range(-1.0f, 1.0f));
        corner.Normalize();
        return corner;
    }
    
}