# 2D generation with perlin noise

#1

Hi guys , i wan’t to ask you something about perlin noise generation in defold, i’ve already try to work on it but i don’t understand how it work ! So, i want to create a game with the generation like terraria starbound or crea, i understand that i need to play with the 1D perlin noise generation, i tried it but that gives me some wierd things. Maybe i have not understand very well the principle of the perlin noise, and that is why i am asking to you if you can explain me simply how it really work (because i am not english and i have not a really good english.
the perlin noise i used look like this :

``````-- https://stackoverflow.com/questions/33425333/lua-perlin-noise-generation-getting-bars-rather-than-squares
-- original code by Ken Perlin: http://mrl.nyu.edu/~perlin/noise/
local function BitAND(a,b)--Bitwise and
local p,c=1,0
while a>0 and b>0 do
local ra,rb=a%2,b%2
if ra+rb>1 then c=c+p end
a,b,p=(a-ra)/2,(b-rb)/2,p*2
end
return c
end

return t * t * t * (t * (t * 6 - 15) + 10)
end

local function lerp( t, a, b )
return a + t * (b - a)
end

local function grad( hash, x, y, z )
local h = BitAND(hash, 15)
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 and 1) == 0 and u or -u) + ((h and 2) == 0 and v or -v)
end

local perlin = {
p = {},
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
},
size = 256,
gx = {},
gy = {},
randMax = 256,
}

function perlin.init()
for i=1,perlin.size do
perlin.p[i] = perlin.permutation[i]
perlin.p[255+i] = perlin.p[i]
end
end

function perlin.noise( x, y, z )
local X = BitAND(math.floor(x), 255) + 1
local Y = BitAND(math.floor(y), 255) + 1
local Z = BitAND(math.floor(z), 255) + 1

x = x - math.floor(x)
y = y - math.floor(y)
z = z - math.floor(z)
local A  = perlin.p[X]+Y
local AA = perlin.p[A]+Z
local AB = perlin.p[A+1]+Z
local B  = perlin.p[X+1]+Y
local BA = perlin.p[B]+Z
local BB = perlin.p[B+1]+Z

return lerp(w, lerp(v, lerp(u, grad(perlin.p[AA  ], x  , y  , z  ),
grad(perlin.p[BA  ], x-1, y  , z  )),
lerp(u, grad(perlin.p[AB  ], x  , y-1, z  ),
grad(perlin.p[BB  ], x-1, y-1, z  ))),
lerp(v, lerp(u, grad(perlin.p[AA+1], x  , y  , z-1),
lerp(u, grad(perlin.p[AB+1], x  , y-1, z-1),
end

return perlin``````

#2

Did you see my example project with an infinite 2D scrollable map?

It uses the exact same perlin noise algorithm as you posted.

#3

Are you talking about the infinite map with the ghosts and the alien ? if it is that i have alredy look at it, but it is for 2D scrollable, i can apply the same system for a map generation like terraria or starboung ?

#4

Sure, why not? It’s still a 2D grid right?

#5

Yes but what i want to do is the top of the map, your map is nicely generate but you don’t have the top of the map, this is full x and y generation ! I want to do the top !
something like this :

the underground with your genaration, for ores, dirt etc could be really usefull but what i want do is juste the top generation for the moment

#6

Ok, so you want to know what to generate at a certain x position on the surface of the world? 1D perlin noise could work. Or use x and y coordinate as a seed to a normal random number generator and use the random number to decide if it’s a tree, a bush, stone or whatever.

#7

I already tried this but i think i made a mistake, i don’t know how to apply that.

#8

Well, maybe if you share what you have or what isn’t working and we can offer suggestions.