perlin.js

function generatePerm()
{
  var list = [151,160,137,91,90,15,131,13,201,95,96,53,194,233,7,225,140,36,
				103,30,69,142,8,99,37,240,21,10,23,190,6,148,247,120,234,75,0,
				26,197,62,94,252,219,203,117,35,11,32,57,177,33,88,237,149,56,
				87,174,20,125,136,171,168,68,175,74,165,71,134,139,48,27,166,
				77,146,158,231,83,111,229,122,60,211,133,230,220,105,92,41,55,
				46,245,40,244,102,143,54,65,25,63,161,1,216,80,73,209,76,132,
 				187,208,89,18,169,200,196,135,130,116,188,159,86,164,100,109,
 				198,173,186,3,64,52,217,226,250,124,123,5,202,38,147,118,126,
 				255,82,85,212,207,206,59,227,47,16,58,17,182,189,28,42,223,183,
 				170,213,119,248,152,2,44,154,163,70,221,153,101,155,167,43,172,
 				9,129,22,39,253,19,98,108,110,79,113,224,232,178,185,112,104,
 				218,246,97,228,251,34,242,193,238,210,144,12,191,179,162,241,
				81,51,145,235,249,14,239,107,49,192,214,31,181,199,106,157,184,
				84,204,176,115,121,50,45,127,4,150,254,138,236,205,93,222,114,
				67,29,24,72,243,141,128,195,78,66,215,61,156,180];
	var end = new Array();
	for(var i=0;i<256;i++)
	{
		end[i] = list[i];
		end[256 + i] = list[i];
	}
	return end;
}
function lerp(t, a, b)
{
	return a + t * (b - a);	
}
function fade(t)
{
	return t* t * t * (t * (t * 6 - 15) + 10);
}
function grad(hash, x, y, z)
{
	var h = hash & 15;
	if(h < 8)
	{
		var u = x;
	}
	else
	{
		var u = y;
	}
		if(h < 4)
		{
			var v = h;
		}
		else
		{
			if(h == 12 || h == 14)
			{
				var v = x;
			}
			else
			{
				var v = z;
			}
	}
	if(h & 1 == 0)
	{
		var abc = u;
	}
	else
	{
		var abc = -u;
	}
	if(h & 2 == 0)
	{
		abc = abc + v;
	}
	else
	{
		abc = abc + -v;
	}
	return abc;
}
function snoise(x, y, z, p)
{
	var floopX = Math.round(x) & 255;
	var floopY = Math.round(y) & 255;
	var floopZ = Math.round(z) & 255;

	x -= Math.round(x);
	y -= Math.round(y);
	z -= Math.round(z);

	var u = fade(x);
	var v = fade(y);
	var w = fade(z);

	var a = p[floopX] + floopY;
	var aa = p[a]

	var a = p[floopX] + floopY;
	var aa = p[a] + floopZ;
	var ab = p[a + 1] + floopZ;
	var b = p[floopX + 1] + floopY;
	var ba = p[b] + floopZ;
	var bb = p[b + 1] + floopZ;
 
	var pAA = p[aa];
	var pAB = p[ab];
	var pBA = p[ba];
	var pBB = p[bb];
	var pAA1 = p[aa + 1];
	var pAB1 = p[ab + 1];
	var pBA1 = p[ba + 1];
	var pBB1 = p[bb + 1];
		 
	var gradAA = grad(pAA,x,y,z);
	var gradBA = grad(pBA, x-1,y,z);
	var gradAB = grad(pAB,x,y-1,z);
	var gradBB = grad(pBB,x-1,y-1,z);
	var gradAA1 = grad(pAA1,x,y,z-1);
	var gradBA1 = grad(pBA1,x-1,y,z-1);
	var gradAB1 = grad(pAB1,x,y-1,z-1);
	var gradBB1 = grad(pBB1,x-1,y-1,z-1);
 
	return lerp(w,
		lerp(v, lerp(u, gradAA, gradBA), lerp(u, gradAB, gradBB)),
		lerp(v, lerp(u, gradAA1, gradBA1), lerp(u,gradAB1,gradBB1))
		);
}

function terrainGenerate(max,min,size)
{
	var seed = 0.123571823;
	var quality = 256;
	var delta = quality + seed;
	var results = new Array();
	for(var x=0;x<size;x++)
	{
		for(var y=0;y<size;y++)
		{
			var noise = snoise(((x) / seed) / delta, ((y) / seed) / delta, 0, generatePerm());
			noise = (noise + 1) / 2 * (max - min) + min;
			results.push((x,y,Math.round(noise),"grass"));
			for(var z=0;z<16;z++)
				if(z < Math.round(noise))
					results.push((x,y,z,"dirt"));
		}
 	}
	return results;
}