Lua - Perlin Noise Generation - Getting bars rather than squares
I'm currently learning Löve 2d/Lua and trying my hand at generating noise using the Perlin Noise algorithm.
I've adapted Ken Perlin's Improved Noise code here:
Code edited with fixes per Doug's answer
-- original code by Ken Perlin: http://mrl.nyu.edu/~perlin/noise/
perlin = {}
perlin.p = {}
perlin.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
}
perlin.size = 256
perlin.gx = {}
perlin.gy = {}
perlin.randMax = 256
function perlin:load( )
for i=1,self.size do
self.p[i] = self.permutation[i]
self.p[256+i] = self.p[i]
end
end
function perlin:noise( x, y, z )
local X = math.floor(x) % 256
local Y = math.floor(y) % 256
local Z = math.floor(z) % 256
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 = self.p[X+1]+Y
local AA = self.p[A+1]+Z
local AB = self.p[A+2]+Z
local B = self.p[X+2]+Y
local BA = self.p[B+1]+Z
local BB = self.p[B+2]+Z
return lerp(w, lerp(v, lerp(u, grad(self.p[AA+1], x , y , z ),
grad(self.p[BA+1], x-1, y , z )),
lerp(u, grad(self.p[AB+1], x , y-1, z ),
grad(self.p[BB+1], x-1, y-1, z ))),
lerp(v, lerp(u, grad(self.p[AB+2], x , y , z-1),
grad(self.p[BA+2], x-1, y , z-1)),
lerp(u, grad(self.p[AB+2], x , y-1, z-1),
grad(self.p[BB+2], x-1, y-1, z-1))))
end
function fade( t )
return t * t * t * (t * (t * 6 - 15) + 10)
end
function lerp( t, a, b )
return a + t * (b - a)
end
function grad( hash, x, y, z )
local h = hash % 16
local u = h < 8 and x or y
local v = h < 4 and y or ((h == 12 or h == 14) and x or z)
return ((h % 2) == 0 and u or -u) + ((h % 3) == 0 and v or -v)
end
and here's my main.lua Löve script:
require 'noise'
function love.load( )
perlin:load()
-- love.graphics.setBackgroundColor(255, 255, 255)
love.window.setMode(500, 500)
end
function love.update( dt )
end
function love.draw( )
for i=1,500 do
for j=1,500 do
local x = perlin:noise(i/10, j/10, 0.3)
love.graphics.setColor(math.floor(x*255), math.floor(x*255), math.floor(x*255))
love.graphics.rectangle("fill", 5*(i-1), 5*(j-1), 5, 5)
end
end
end
The problem I'm encountering is that rather than getting a nice image of pseudorandom squares, I'm getting some gradient-like bars like this:
I'm pretty stumped as to why I'm not getting the usual noise rendering.
EDIT: Here's the working rendering!
One problem:
local X = math.floor(x) and 255
local Y = math.floor(y) and 255
local Z = math.floor(z) and 255
should be
local X = math.floor(x) & 255
local Y = math.floor(y) & 255
local Z = math.floor(z) & 255
assuming you have Lua 5.3.x. If you have an earlier version of Lua, there are bitwise libraries that may or may not be available for Löve. So, in this case you can use:
local X = math.floor(x) % 256
local Y = math.floor(y) % 256
local Z = math.floor(z) % 256
Explanation: The conjunction operator and returns its first argument if this value is false or nil; otherwise, and returns its second argument.