
It is to my knowledge that the Techcraft engine current utilizes Simplex Noise.
I don't know if the private rewrite uses Simplex too, but I would highly suggest switching over the Perlin Noise, simply because at 2 and 3 dimensions, Perlin Noise is faster than Simplex. The computation cost for Perlin Noise is 2^i, while Simplex
Noise is i^2. While there is no performance gain at two dimensions, at three dimensions, Perlin noise is 8, while Simplex noise is 9.
Also, Perlin Noise apparently fits block games better, I forget why, but I remember it has something to do with the algorithm it uses, and how Simplex uses triangles.
I've created a class based on Ken Perlin's actual implementation of Improved Noise (http://mrl.nyu.edu/~perlin/noise/)
public class PerlinNoise
{
private int[] permutations = new int[512];
private Random random;
public PerlinNoise()
: this(Environment.TickCount)
{ }
public PerlinNoise(int seed)
{
random = new Random(seed);
for (int i = 0; i < 256; i++)
{
permutations[i] = i;
}
for (int i = 0; i < 256; i++)
{
int k = random.Next(256  i) + i;
int l = permutations[i];
permutations[i] = permutations[k];
permutations[k] = l;
permutations[i + 256] = permutations[i];
}
}
private int fastfloor(float x)
{
return x > 0 ? (int)x : (int)x  1;
}
private float fade(float t)
{
return t * t * t * (t * (t * 6  15) + 10);
}
private float lerp(float t, float a, float b)
{
return a + t * (b  a);
}
public float grad(int hash, float x, float y, float z)
{
int h = hash & 15;
float u = h < 8 ? x : y,
v = h < 4 ? y : h == 12  h == 14 ? x : z;
return ((h & 1) == 0 ? u : u) + ((h & 2) == 0 ? v : v);
}
public float noise3d(float x, float y, float z)
{
int X = fastfloor(x) & 0xff,
Y = fastfloor(y) & 0xff,
Z = fastfloor(z) & 0xff;
x = fastfloor(x);
y = fastfloor(y);
z = fastfloor(z);
float u = fade(x);
float v = fade(y);
float w = fade(z);
int A = permutations[X] + Y, AA = permutations[A] + Z, AB = permutations[A + 1] + Z,
B = permutations[X + 1] + Y, BA = permutations[B] + Z, BB = permutations[B + 1] + Z;
return lerp(w, lerp(v, lerp(u, grad(permutations[AA], x, y, z),
grad(permutations[BA], x  1, y, z)),
lerp(u, grad(permutations[AB], x, y  1, z),
grad(permutations[BB], x  1, y  1, z))),
lerp(v, lerp(u, grad(permutations[AA + 1], x, y, z  1),
grad(permutations[BA + 1], x  1, y, z  1)),
lerp(u, grad(permutations[AB + 1], x, y  1, z  1),
grad(permutations[BB + 1], x  1, y  1, z  1))));
}
public float noise2d(float x, float y)
{
return noise3d(x, y, 0f);
}
}
It outputs 0.0F all the time, and I have no idea why. Hopefully you guys can successfully implement this in the next commit. :)


Coordinator
Jul 6, 2011 at 2:17 AM

Good to hear from one of our old IRC mates ;)
Thats definitely worth investigating ! But not now, we are already overwhelmed by all our own super secret gameplay additions and all the bugs they introduce in our engine ;)
By the way, followers of the opensource techcraft will be the first to know when we will release something !


Developer
Jul 6, 2011 at 9:22 AM

Hi Tony,
The newtake.model.terrain namespace has a 3d simplex method:
public static float noise(float xin, float yin, float zin)
In your code the noise2d method parses a zero float for z. Is that what you refer to as returning 0.0f from the noise3d method?



Enomi: Can't wait for the day you guys announce them. :)
Jacoo: Not exactly. At first, I just decided that I'd just use 3d noise for my 2d noise, but just setting the z value to 0. However, when that failed (it outputted 0), I decided to see if the noise3d function even worked. When I tried noise3d(args[0]...),
it still put out 0. So I'm really confused about this. :P


Developer
Jul 6, 2011 at 9:17 PM

Hi,
im just curious but did you try replacing the randomness in the permutations with ken's array, just to see if it makes a difference?


Jul 6, 2011 at 9:20 PM
Edited Jul 6, 2011 at 9:22 PM

Yup, I did.
Still 0. :(
I've also tried the old fashioned
for(int i = 0; i < 256; i++)
permutations[i] = permuations[i + 256] = i;


Developer
Mar 19, 2012 at 12:43 PM

that could be related to that normal perlin noise returns 0 for int values. More information over; http://www.programmersheaven.com/2/perlin
Another disadvantage that might not be obvious is that the noise function always returns 0 at integer values. Although this is not noticable on static images it is very apparent on animated images. I made a 3D perlin noise function
and rendered it on a 2D texture map while moving along the zaxis, this had the effect of a pulsating map. This because every time the z value was integer there where many values around 0, while the z where between integer values there where more randomness.


Developer
Mar 19, 2012 at 1:01 PM

and I'm really not sure if perlin noise is better in complexity (even in lower dimensions)  http://en.wikipedia.org/wiki/Simplex_noise

