lib/noise: move ImprovedNoise from the rosetta perlin noise example

Signed-off-by: Alexis Laferrière <alexis.laf@xymus.net>

diff --git a/examples/rosettacode/perlin_noise.nit b/examples/rosettacode/perlin_noise.nit
index 0733bbf..a5cd314 100644 (file)
--- a/examples/rosettacode/perlin_noise.nit
+++ b/examples/rosettacode/perlin_noise.nit
@@ -8,69 +8,7 @@
 # See: <http://rosettacode.org/wiki/Perlin_noise>
 module perlin_noise
 
-redef universal Float
-       # Smoothened `self`
-       fun fade: Float do return self*self*self*(self*(self*6.0-15.0)+10.0)
-end
-
-# Improved noise
-class ImprovedNoise
-       # Permutations
-       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]
-
-       # Noise value in [-1..1] at 3d coordinates `x, y, z`
-       fun noise(x, y, z: Float): Float
-       do
-               var xx = x.to_i & 255
-               var yy = y.to_i & 255
-               var zz = z.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
-       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
+import noise
 
 var map = new ImprovedNoise
 print map.noise(3.14, 42.0, 7.0).to_precision(17)

diff --git a/lib/noise.nit b/lib/noise.nit
index ba09bc1..4e42820 100644 (file)
--- a/lib/noise.nit
+++ b/lib/noise.nit
@@ -359,3 +359,72 @@ redef universal Int
                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]
+
+       # 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