Perlin noise: Difference between revisions

=={{header|Nim}}==

{{trans|Kotlin}}

<lang Nim>import math

const 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

]

const P = static:

var a: array[512, int]

for i, val in Permutation:

a[i] = val

a[i + 256] = val

a

func fade(t: float): float = t * t * t * (t * (t * 6 - 15) + 10)

func lerp(t, a, b: float): float = a + t * (b - a)

func grad(hash: int; x, y, z: float): float =

## Convert low 4 bits of hash code into 12 gradient directions.

let h = hash and 15

let u = if h < 8: x else: y

let v = if h < 4: y elif h == 12 or h == 14: x else: z

result = (if (h and 1) == 0: u else: -u) + (if (h and 2) == 0: v else: -v)

func noise(x, y, z: float): float =

# Find unit cube that contains point.

let

xi = int(x) and 255

yi = int(y) and 255

zi = int(z) and 255

# Find relative x, y, z of point in cube.

let

x = x - floor(x)

y = y - floor(y)

z = z - floor(z)

# Compute fade curves for each of x, y, z.

let

u = fade(x)

v = fade(y)

w = fade(z)

# Hash coordinates of the 8 cube corners and

# add blended results from 8 corners of cube.

let

a = P[xi] + yi

aa = P[a] + zi

ab = P[a + 1] + zi

b = P[xi + 1] + yi

ba = P[b] + zi

bb = P[b + 1] + zi

result = lerp(w, lerp(v, lerp(u, grad(P[aa], x, y, z),

grad(P[ba], x - 1, y, z)),

lerp(u, grad(P[ab], x, y - 1, z),

grad(P[bb], x - 1, y - 1, z))),

lerp(v, lerp(u, grad(P[aa + 1], x, y, z - 1),

grad(P[ba + 1], x - 1, y, z - 1)),

lerp(u, grad(P[ab + 1], x, y - 1, z - 1),

grad(P[bb + 1], x - 1, y - 1, z - 1))))

when isMainModule:

echo noise(3.14, 42, 7)</lang>

{{out}}

<pre>0.1369199587840001</pre>