Initial Commit

diff --git a/README b/README
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+A dragonfire CSM that does terraforming automatically using perlin noise. 

diff --git a/init.lua b/init.lua
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+perlin = dofile(minetest.get_modpath("perlin") .. "/perlin.lua")
+
+local start, height, stretch
+
+minetest.register_chatcommand("perlin", {
+       description = "Start perlin terraforming",
+       param = "<height> <stretch>",
+       func = function(param)
+               local sparam = param:split(" ")
+               start, height, stretch = math.floor(minetest.localplayer:get_pos().y), sparam[1], sparam[2]
+       end     
+})
+
+minetest.register_chatcommand("perlinstop", {
+       description = "Abort perlin terraforming",
+       func = function(param)
+               start, height, stretch = nil
+       end     
+})
+
+minetest.register_globalstep(function()
+       if start then
+               local player = minetest.localplayer
+               local pos = vector.floor(player:get_pos())
+               for x = pos.x - 1, pos.x + 1 do
+                       for z = pos.z - 1, pos.z + 1 do
+                               local y = math.floor(start + height * perlin:noise(x / stretch, z / stretch))
+                               local p = vector.new(x, y, z)
+                               minetest.place_node(p)
+                       end
+               end
+       end 
+end)

diff --git a/mod.conf b/mod.conf
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+name = perlin
+description = A bot that does terraforming automatically using perlin noise.
+author = Fleckenstein

diff --git a/perlin.lua b/perlin.lua
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+++ b/perlin.lua
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+--[[
+    Implemented as described here:
+    http://flafla2.github.io/2014/08/09/perlinnoise.html
+]]--
+
+local perlin = {}
+perlin.p = {}
+
+local bit32 = {}
+function bit32.band(a, b)
+    local result = 0
+    local bitval = 1
+    while a > 0 and b > 0 do
+      if a % 2 == 1 and b % 2 == 1 then -- test the rightmost bits
+          result = result + bitval      -- set the current bit
+      end
+      bitval = bitval * 2 -- shift left
+      a = math.floor(a/2) -- shift right
+      b = math.floor(b/2)
+    end
+    return result
+end
+
+-- Hash lookup table as defined by Ken Perlin
+-- This is a randomly arranged array of all numbers from 0-255 inclusive
+local permutation = {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
+}
+
+-- p is used to hash unit cube coordinates to [0, 255]
+for i=0,255 do
+    -- Convert to 0 based index table
+    perlin.p[i] = permutation[i+1]
+    -- Repeat the array to avoid buffer overflow in hash function
+    perlin.p[i+256] = permutation[i+1]
+end
+
+-- Return range: [-1, 1]
+function perlin:noise(x, y, z)
+    y = y or 0
+    z = z or 0
+
+    -- Calculate the "unit cube" that the point asked will be located in
+    local xi = bit32.band(math.floor(x),255)
+    local yi = bit32.band(math.floor(y),255)
+    local zi = bit32.band(math.floor(z),255)
+
+    -- Next we calculate the location (from 0 to 1) in that cube
+    x = x - math.floor(x)
+    y = y - math.floor(y)
+    z = z - math.floor(z)
+
+    -- We also fade the location to smooth the result
+    local u = self.fade(x)
+    local v = self.fade(y)
+    local w = self.fade(z)
+
+    -- Hash all 8 unit cube coordinates surrounding input coordinate
+    local p = self.p
+    local A, AA, AB, AAA, ABA, AAB, ABB, B, BA, BB, BAA, BBA, BAB, BBB
+    A   = p[xi  ] + yi
+    AA  = p[A   ] + zi
+    AB  = p[A+1 ] + zi
+    AAA = p[ AA ]
+    ABA = p[ AB ]
+    AAB = p[ AA+1 ]
+    ABB = p[ AB+1 ]
+
+    B   = p[xi+1] + yi
+    BA  = p[B   ] + zi
+    BB  = p[B+1 ] + zi
+    BAA = p[ BA ]
+    BBA = p[ BB ]
+    BAB = p[ BA+1 ]
+    BBB = p[ BB+1 ]
+
+    -- Take the weighted average between all 8 unit cube coordinates
+    return self.lerp(w,
+        self.lerp(v,
+            self.lerp(u,
+                self:grad(AAA,x,y,z),
+                self:grad(BAA,x-1,y,z)
+            ),
+            self.lerp(u,
+                self:grad(ABA,x,y-1,z),
+                self:grad(BBA,x-1,y-1,z)
+            )
+        ),
+        self.lerp(v,
+            self.lerp(u,
+                self:grad(AAB,x,y,z-1), self:grad(BAB,x-1,y,z-1)
+            ),
+            self.lerp(u,
+                self:grad(ABB,x,y-1,z-1), self:grad(BBB,x-1,y-1,z-1)
+            )
+        )
+    )
+end
+
+-- Gradient function finds dot product between pseudorandom gradient vector
+-- and the vector from input coordinate to a unit cube vertex
+perlin.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
+}
+function perlin:grad(hash, x, y, z)
+    return self.dot_product[bit32.band(hash,0xF)](x,y,z)
+end
+
+-- Fade function is used to smooth final output
+function perlin.fade(t)
+    return t * t * t * (t * (t * 6 - 15) + 10)
+end
+
+function perlin.lerp(t, a, b)
+    return a + t * (b - a)
+end
+
+return perlin