declassify some projects

heavbiome/perlin.lua

@@ -0,0 +1,134 @@
+local defaultSeed = 1337
+
+local dot_product = {
+  [0x0]=function(x,y,z) return  x + y end,
+  [0x1]=function(x,y,z) return -x + y end,
+  [0x2]=function(x,y,z) return  x - y end,
+  [0x3]=function(x,y,z) return -x - y end,
+  [0x4]=function(x,y,z) return  x + z end,
+  [0x5]=function(x,y,z) return -x + z end,
+  [0x6]=function(x,y,z) return  x - z end,
+  [0x7]=function(x,y,z) return -x - z end,
+  [0x8]=function(x,y,z) return  y + z end,
+  [0x9]=function(x,y,z) return -y + z end,
+  [0xA]=function(x,y,z) return  y - z end,
+  [0xB]=function(x,y,z) return -y - z end,
+  [0xC]=function(x,y,z) return  y + x end,
+  [0xD]=function(x,y,z) return -y + z end,
+  [0xE]=function(x,y,z) return  y - x end,
+  [0xF]=function(x,y,z) return -y - z end
+}
+
+local grad = function(hash, x,y,z)
+  return dot_product[hash % 0x10](x,y,z)
+end
+
+local fade = function(t)
+  return t * t * t * (t * (t * 6 - 15) + 10)
+end
+
+local lerp = function(t,a,b)
+  return a + t * (b - a)
+end
+
+local generatePermutation = function(seed)
+  math.randomseed(seed)
+
+  local permutation = {0}
+
+  for i=1,255 do
+    table.insert(permutation,math.random(1,#permutation+1),i)
+  end
+
+  local p = {}
+
+  for i=0,255 do
+    p[i] = permutation[i+1]
+    p[i+256] = permutation[i+1]
+  end
+
+  return p
+end
+
+perlin = {}
+perlin.__index = perlin
+
+perlin.noise = function(self,x,y,z)
+  y = y or 0
+  z = z or 0
+
+  local xi = math.floor(x) % 0x100
+  local yi = math.floor(y) % 0x100
+  local zi = math.floor(z) % 0x100
+
+  x = x - math.floor(x)
+  y = y - math.floor(y)
+  z = z - math.floor(z)
+
+  local u = fade(x)
+  local v = fade(y)
+  local w = fade(z)
+
+  local A, AA, AB, AAA, ABA, AAB, ABB, B, BA, BB, BAA, BBA, BAB, BBB
+  A   = self.p[xi  ] + yi
+  AA  = self.p[A   ] + zi
+  AB  = self.p[A+1 ] + zi
+  AAA = self.p[ AA ]
+  ABA = self.p[ AB ]
+  AAB = self.p[ AA+1 ]
+  ABB = self.p[ AB+1 ]
+
+  B   = self.p[xi+1] + yi
+  BA  = self.p[B   ] + zi
+  BB  = self.p[B+1 ] + zi
+  BAA = self.p[ BA ]
+  BBA = self.p[ BB ]
+  BAB = self.p[ BA+1 ]
+  BBB = self.p[ BB+1 ]
+
+  return lerp(w,
+    lerp(v,
+      lerp(u,
+        grad(AAA,x,y,z),
+        grad(BAA,x-1,y,z)
+      ),
+      lerp(u,
+        grad(ABA,x,y-1,z),
+        grad(BBA,x-1,y-1,z)
+      )
+    ),
+    lerp(v,
+      lerp(u,
+        grad(AAB,x,y,z-1), grad(BAB,x-1,y,z-1)
+      ),
+      lerp(u,
+        grad(ABB,x,y-1,z-1), grad(BBB,x-1,y-1,z-1)
+      )
+    )
+  )
+end
+
+setmetatable(perlin,{
+  __call = function(self,seed)
+    seed = seed or defaultSeed
+
+    return setmetatable({
+      seed = seed,
+      p = generatePermutation(seed),
+    },self)
+  end
+})
+
+--[[
+EXAMPLE
+  local p1 = perlin(1338)
+  local p2 = perlin(1337)
+
+  local x,y,z = 1.0,2.0,3.0
+
+  print(p1:noise(x,y,z))
+  print(p2:noise(x,y,z))
+  
+  >> 0.23456
+  >> 0.47598
+--]]