1
0
mirror of https://github.com/Refactorio/RedMew.git synced 2024-12-16 10:19:27 +02:00
RedMew/map_gen/shared/perlin_noise.lua
Matthew 0927a839b8
Fix linting (#657)
Fix linting warnings
2019-01-19 11:34:29 -05:00

147 lines
4.3 KiB
Lua

--[[
Implemented as described here:
http://flafla2.github.io/2014/08/09/perlinnoise.html
]] --
local 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
-- Gradient function finds dot product between pseudorandom gradient vector
-- and the vector from input coordinate to a unit cube vertex
local dot_product = {
[0x0] = function(x, y)
return x + y
end,
[0x1] = function(x, y)
return -x + y
end,
[0x2] = function(x, y)
return x - y
end,
[0x3] = function(x, y, _)
return -x - y
end,
[0x4] = function(x, _, z)
return x + z
end,
[0x5] = function(x, _, z)
return -x + z
end,
[0x6] = function(x, _, z)
return x - z
end,
[0x7] = function(x, _, z)
return -x - z
end,
[0x8] = function(_, y, z)
return y + z
end,
[0x9] = function(_, y, z)
return -y + z
end,
[0xA] = function(_, y, z)
return y - z
end,
[0xB] = function(_, y, z)
return -y - z
end,
[0xC] = function(x, y, _)
return y + x
end,
[0xD] = function(_, y, z)
return -y + z
end,
[0xE] = function(x, y, _)
return y - x
end,
[0xF] = function(_, y, z)
return -y - z
end
}
local function grad(hash, x, y, z)
return dot_product[bit32.band(hash, 0xF)](x, y, z)
end
-- Fade function is used to smooth final output
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
-- Return range: [-1, 1]
function Perlin.noise(x, y, z)
y = y or 0
z = z or 0
-- This prevents integer inputs returning 0, which causes 'straight line' artifacts.
x = x - 0.55077056353912
y = y - 0.131357755512
z = z - 0.20474238274619
-- 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 = fade(x)
local v = fade(y)
local w = fade(z)
-- Hash all 8 unit cube coordinates surrounding input coordinate
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 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
return Perlin