--[[
| This file was obtained through the combined efforts
| of Madbluntz & Plymouth Antiquarian Society.
|
| Credits: lifestorm, Gregory Wayne Rossel JR.,
| 	Maloy, DrPepper10 @ RIP, Atle!
|
| Visit for more: https://plymouth.thetwilightzone.ru/
--]]

--[[
    Implemented as described here:
    http://flafla2.github.io/2014/08/09/perlinnoise.html

    Copied from: https://gist.github.com/SilentSpike/25758d37f8e3872e1636d90ad41fe2ed
]]--

local floor,band,clamp,max = math.floor,bit.band,math.Clamp,math.max

perlin = {}
local p = {}

-- 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
    p[i] = permutation[i + 1]
    -- Repeat the array to avoid buffer overflow in hash function
    p[i + 256] = permutation[i + 1]
end
-- Functions
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 function grad(hash, x, y, z)
    return dot_product[band(hash,0xF)](x,y,z)
end
local function fade(t)
    return t * t * t * (t * (t * 6 - 15) + 10)
end
local function lerp(t, a, b)
    return a + t * (b - a)
end
function perlin.noise(x, y, z, zoom) -- [-1 , 1]
    zoom = zoom or 100
    x = x / zoom
    y = y and y / zoom or 0
    z = z and z / zoom or 0

    -- Calculate the "unit cube" that the point asked will be located in
    local xi = floor(x) % 256
    local yi = floor(y) % 256
    local zi = floor(z) % 256

    -- Next we calculate the location (from 0 to 1) in that cube
    x = x - floor(x)
    y = y - floor(y)
    z = z - floor(z)

    -- We also fade the location to smooth the result
    local u = fade(x)
    local v = fade(y)
    local w = fade(z)

    -- Hash all 8 unit cube coordinates surrounding input coordinate
    local A   = p[xi    ] + yi
    local AA  = p[A     ] + zi
    local AB  = p[A + 1 ] + zi
    local AAA = p[ AA   ]
    local ABA = p[ AB   ]
    local AAB = p[ AA + 1 ]
    local ABB = p[ AB + 1 ]

    local B   = p[xi + 1] + yi
    local BA  = p[B     ] + zi
    local BB  = p[B + 1 ] + zi
    local BAA = p[ BA   ]
    local BBA = p[ BB   ]
    local BAB = p[ BA + 1 ]
    local BBB = p[ BB + 1 ]

    -- Take the weighted average between all 8 unit cube coordinates
    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
function perlin.range(x, y ,z, zoom) -- [0 - 1]
    return (1 + perlinnoise(x, y, z, zoom)) / 2
end
function perlin.rangeSub(x, y, z , zoom, n)
    return max(0,(perlin.range(x, y ,z, zoom) - n ) / (1 - n))
end