Merge: Basename fix

[nit.git] / lib / noise.nit

diff --git a/lib/noise.nit b/lib/noise.nit
index 7f26401..ba09bc1 100644 (file)
--- 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 +348,14 @@ 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