47 lines
1.4 KiB
Rust
47 lines
1.4 KiB
Rust
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use rand::distributions::{Distribution, Uniform};
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use rand::Rng;
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use crate::Point3;
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pub struct Perlin {
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ranfloat: Vec<f64>,
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perm_x: Vec<usize>,
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perm_y: Vec<usize>,
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perm_z: Vec<usize>,
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}
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impl Perlin {
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const POINT_COUNT: usize = 256;
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pub fn new() -> Self {
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let range = Uniform::from(0.0..1.0);
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let mut rng = rand::thread_rng();
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let mut ranfloat = Vec::with_capacity(Perlin::POINT_COUNT);
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(0..Perlin::POINT_COUNT).for_each(|_i|ranfloat.push(range.sample(&mut rng)));
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Perlin {
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ranfloat,
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perm_x: Perlin::perlin_generate_perm(),
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perm_y: Perlin::perlin_generate_perm(),
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perm_z: Perlin::perlin_generate_perm(),
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}
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}
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pub fn noise(&self, point: &Point3) -> f64 {
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let i = ((4.0 * point.x()) as i32) & 255;
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let j = ((4.0 * point.y()) as i32) & 255;
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let k= ((4.0 * point.z()) as i32) & 255;
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let idx = self.perm_x[i as usize] ^ self.perm_y[j as usize] ^ self.perm_z[k as usize];
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self.ranfloat[idx]
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}
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fn perlin_generate_perm() -> Vec<usize> {
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let mut p = Vec::with_capacity(Perlin::POINT_COUNT);
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(0..Perlin::POINT_COUNT).for_each(|i| p.push(i));
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let mut rng = rand::thread_rng();
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(1..Perlin::POINT_COUNT).rev().for_each(|idx| {
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let target = rng.gen_range(0..=idx);
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p.swap(idx, target);
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});
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p
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}
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}
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