X-Git-Url: http://nitlanguage.org

diff --git a/lib/noise.nit b/lib/noise.nit
index 7f26401..cf4d0fa 100644
--- a/lib/noise.nit
+++ b/lib/noise.nit
@@ -12,7 +12,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-# Provides the noise generators `PerlinNoise` and `InterpolatedNoise`
+# Noise generators `PerlinNoise` and `InterpolatedNoise`
 module noise is serialize
 
 import serialization
@@ -66,7 +66,7 @@ abstract class Noise
 	# Seed to the random number generator `gradient_vector`
 	#
 	# By default, `seed` has a random value created with `Int::rand`.
-	var seed: Int = 19559.rand is lazy, writable
+	var seed: Int = 19511359.rand is lazy, writable
 end
 
 # 2D Perlin noise generator using layered `InterpolatedNoise`
@@ -197,7 +197,7 @@ class PerlinNoise
 	# Used to get seeds for layers from the previous layers or `seed`.
 	protected fun pseudo_random(value: Int): Int
 	do
-		return value + 2935391 % 954847
+		return (value * 3537391).mask % 1291377
 	end
 end
 
@@ -301,7 +301,8 @@ class InterpolatedNoise
 		var ix1 = sx.lerp(n0, n1)
 		var val = sy.lerp(ix0, ix1)
 
-		# Return value in [min...max] from val in [-0.5...0.5]
+		# Return value in [min...max] from val in [-1.0...1.0]
+		val /= 2.0
 		val += 0.5
 		return val.lerp(min, max)
 	end
@@ -321,10 +322,20 @@ class InterpolatedNoise
 		#
 		# These magic prime numbers were determined good enough by
 		# non-emperical experimentation. They may need to be changed/improved.
-		var i = 17957*seed + 45127*x + 22613*y
-		var mod = 19031
+		var seed = 817721 + self.seed
+		var i = seed * (x+seed) * 25111217 * (y+seed) * 72233613
+		var mod = 137121
+		var angle = (i.mask.abs%mod).to_f*2.0*pi/mod.to_f
+
+		# Debug code to evaluate the efficiency of the random angle generator
+		# The average of the produced angles should be at pi
+		#
+		#var sum = once new Container[Float](0.0)
+		#var count = once new Container[Float](0.0)
+		#sum.item += angle
+		#count.item += 1.0
+		#if count.item.to_i % 1000 == 0 then print "avg:{sum.item/count.item}/{count.item} i:{i} a:{angle} ({x}, {y}: {seed})"
 
-		var angle = (i%mod).to_f*2.0*pi/mod.to_f
 		if w == 0 then return angle.cos
 		return angle.sin
 	end
@@ -337,3 +348,83 @@ class InterpolatedNoise
 		return dx*gradient_vector(ix, iy, 0) + dy*gradient_vector(ix, iy, 1)
 	end
 end
+
+redef universal Int
+	# The value of the least-significant 30 bits of `self`
+	#
+	# This mask is used as compatibility with 32 bits architecture.
+	# The missing 2 bits are used to tag integers by the Nit system.
+	private fun mask: Int
+	do
+		return self & 0x3FFF_FFFF
+	end
+end
+
+redef universal Float
+	# Smoothened `self`, used by `ImprovedNoise`
+	private fun fade: Float do return self*self*self*(self*(self*6.0-15.0)+10.0)
+end
+
+# Direct translation of Ken Perlin's improved noise Java implementation
+#
+# This implementation differs from `PerlinNoise` on two main points.
+# This noise is calculated for a 3D point, vs 2D in `PerlinNoise`.
+# `PerlinNoise` is based off a customizable seed, while this noise has a static data source.
+class ImprovedNoise
+
+	# Permutations
+	private var p: Array[Int] = [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] * 2
+
+	# Noise value in [-1..1] at 3D coordinates `x, y, z`
+	fun noise(x, y, z: Float): Float
+	do
+		var xx = x.floor.to_i & 255
+		var yy = y.floor.to_i & 255
+		var zz = z.floor.to_i & 255
+
+		x -= x.floor
+		y -= y.floor
+		z -= z.floor
+
+		var u = x.fade
+		var v = y.fade
+		var w = z.fade
+
+		var a  = p[xx  ] + yy
+		var aa = p[a   ] + zz
+		var ab = p[a+1 ] + zz
+		var b  = p[xx+1] + yy
+		var ba = p[b   ] + zz
+		var bb = p[b+1 ] + zz
+
+		return w.lerp(v.lerp(u.lerp(grad(p[aa  ], x,     y,     z    ),
+		                            grad(p[ba  ], x-1.0, y,     z    )),
+		                     u.lerp(grad(p[ab  ], x,     y-1.0, z    ),
+		                            grad(p[bb  ], x-1.0, y-1.0, z    ))),
+                      v.lerp(u.lerp(grad(p[aa+1], x,     y,     z-1.0),
+		                            grad(p[ba+1], x-1.0, y,     z-1.0)),
+		                     u.lerp(grad(p[ab+1], x,     y-1.0, z-1.0),
+		                            grad(p[bb+1], x-1.0, y-1.0, z-1.0))))
+	end
+
+	# Value at a corner of the grid
+	private fun grad(hash: Int, x, y, z: Float): Float
+	do
+		var h = hash & 15
+		var u = if h < 8 then x else y
+		var v = if h < 4 then y else if h == 12 or h == 14 then x else z
+		return (if h.is_even then u else -u) + (if h & 2 == 0 then v else -v)
+	end
+end