koobas.hobune.stream
How to make Perlin Noise Seemless on a sphere?
So, i have made a script to generate perlinnoise, randomly. But what i need is for it to be able to loop on a sphere, and not go small at the top. Here is the script: using UnityEngine; using System.Collections;
public class Planet : MonoBehaviour
{
public int width = 256;
public int height = 256;
public float scale = 20f;
public float offsetX = 100f;
public float offsetY = 100f;
private void Start()
{
offsetX = Random.Range(0f, 10000f);
offsetY = Random.Range(0f, 10000f);
}
void Update()
{
Renderer renderer = GetComponent<Renderer>();
renderer.material.mainTexture = GenerateTexture();
}
Texture2D GenerateTexture()
{
Texture2D texture = new Texture2D(width, height);
for (int x = 0; x < width; x++)
{
for (int y = 0; y < height; y++)
{
Color color = CalculateColor(x, y);
texture.SetPixel(x, y, color);
}
}
texture.Apply();
return texture;
}
Color CalculateColor(int x, int y)
{
float xCoord = (float)x / width * scale + offsetX;
float yCoord = (float)y / height * scale + offsetY;
float sample = Mathf.PerlinNoise(xCoord, yCoord);
return new Color(sample, sample, sample);
}
}
Problem is, i dont know how to approach this.
If you don't want any seams and warping on your sphere texture, you will need to generate the texture from a 3D perlin noise.
The Sphere is mapped in a longitude/latitude way, so you can deduce the 3D coordinates from the UV (or 2d coords) and some trigonometry :
y = sin( UVy * pi - pi/2 )
x = cos( UVx 2 pi ) cos( UVy pi - pi/2 )
z = sin( UVx 2 pi ) cos( UVy pi - pi/2 )
x, y and z are now values in the range [-1;1]. You need to remap them to [0;1] by doing : value = value * 0.5 + 0.5.
Now you can get a 3D perlin noise value by chaining 2 2D perlin noise :float sample = Mathf.PerlinNoise( Mathf.PerlinNoise(x, y),z);
I haven't tried, but this should work.
