1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
|
use crate::vec3::{Vec3, Point3};
const POINT_COUNT: usize = 256;
pub struct Perlin {
ranvec: Vec<Vec3>,
perm_x: Vec<usize>,
perm_y: Vec<usize>,
perm_z: Vec<usize>,
}
impl Perlin {
pub fn new() -> Self {
let mut ranvec = Vec::with_capacity(POINT_COUNT);
for _ in 0..POINT_COUNT {
ranvec.push(Vec3::random_in_range(-1.0, 1.0).unit_vector());
}
Self {
ranvec,
perm_x: Self::generate_perm(),
perm_y: Self::generate_perm(),
perm_z: Self::generate_perm(),
}
}
pub fn turb(&self, point: &Point3, depth: u32) -> f64 {
let mut accum = 0.0;
let mut temp_point = point.clone();
let mut weight = 1.0;
for _ in 0..depth {
accum += weight * self.noise(&temp_point);
weight *= 0.5;
temp_point *= 2.0;
}
accum.abs()
}
pub fn turb_dsw(&self, point: &Point3, depth: u32, factor: f64) -> f64 {
let mut accum = 0.0;
let mut temp_point = point.clone();
let mut weight = 1.0;
for _ in 0..depth {
accum += weight * self.noise(&temp_point);
temp_point *= 2.0;
temp_point += temp_point.xy_diff(&|p: &Vec3| -> f64 {weight * self.noise(p)}) * factor;
weight *= 0.5;
}
accum.abs()
}
pub fn noise(&self, point: &Point3) -> f64 {
let u = point.x - point.x.floor();
let v = point.y - point.y.floor();
let w = point.z - point.z.floor();
let i = point.x.floor() as i32;
let j = point.y.floor() as i32;
let k = point.z.floor() as i32;
let mut c: [[[Vec3; 2]; 2]; 2] = Default::default();
for di in 0..2 {
for dj in 0..2 {
for dk in 0..2 {
c[di][dj][dk] = self
.ranvec
.get(
(self.perm_x.get(((i + di as i32) & 255) as usize).unwrap()
^ self.perm_y.get(((j + dj as i32) & 255) as usize).unwrap()
^ self.perm_z.get(((k + dk as i32) & 255) as usize).unwrap())
as usize,
)
.unwrap().clone();
}
}
}
Self::trilinear_interpolate(c, u, v, w)
}
fn trilinear_interpolate(c: [[[Vec3; 2]; 2]; 2], u: f64, v: f64, w: f64) -> f64 {
let uu = u * u * (3.0 - 2.0 * u);
let vv = v * v * (3.0 - 2.0 * v);
let ww = w * w * (3.0 - 2.0 * w);
let mut accum: f64 = 0.0;
for i in 0..2 {
for j in 0..2 {
for k in 0..2 {
let i_f = i as f64;
let j_f = j as f64;
let k_f = k as f64;
let weight_v = Vec3 { x: u - i_f, y: v - j_f, z: w - k_f };
accum += (i_f * uu + (1.0 - i_f) * (1.0 - uu)) *
(j_f * vv + (1.0 - j_f) * (1.0 - vv)) *
(k_f * ww + (1.0 - k_f) * (1.0 - ww)) *
c[i][j][k].dot(&weight_v);
}
}
}
accum
}
fn generate_perm() -> Vec<usize> {
let mut p = (0..POINT_COUNT).collect();
Self::permute(&mut p, POINT_COUNT);
p
}
fn permute(p: &mut Vec<usize>, n: usize) {
for i in (1..n).rev() {
p.swap(i, rand::random::<usize>() % i);
}
}
}
|