97 lines
3.0 KiB
Rust
97 lines
3.0 KiB
Rust
use rand::Rng;
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use crate::{Point3, Vec3};
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pub struct Perlin {
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ranvec: Vec<Vec3>,
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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 mut ranvec = Vec::with_capacity(Perlin::POINT_COUNT);
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(0..Perlin::POINT_COUNT).for_each(|_i|ranvec.push(Vec3::random(-1.0, 1.0)));
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Perlin {
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ranvec,
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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 default_turbulence(&self, point: &Point3) -> f64 {
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self.turbulence(point, 7)
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}
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pub fn turbulence(&self, point: &Point3, depth: i32) -> f64 {
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let mut accum = 0.0;
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let mut temp_p = point.clone();
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let mut weight = 1.0;
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for _i in 0..depth {
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accum += weight * self.noise(&temp_p);
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weight *= 0.5;
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temp_p *= 2.0;
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}
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accum.abs()
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}
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pub fn noise(&self, point: &Point3) -> f64 {
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let u = point.x() - point.x().floor();
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let v = point.y() - point.y().floor();
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let w = point.z() - point.z().floor();
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let i = point.x().floor() as i32;
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let j = point.y().floor() as i32;
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let k = point.z().floor() as i32;
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let mut c: [[[Vec3; 2]; 2]; 2] = [[[Vec3::default(); 2]; 2]; 2];
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for di in 0..2 {
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for dj in 0..2 {
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for dk in 0..2 {
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let idx = self.perm_x[((i+di) & 255) as usize] ^
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self.perm_y[((j+dj) & 255) as usize] ^
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self.perm_z[((k+dk) & 255) as usize];
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c[di as usize][dj as usize][dk as usize] = self.ranvec[idx];
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}
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}
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}
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Perlin::perlin_interp(c, u, v, w)
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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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fn perlin_interp(c: [[[Vec3; 2]; 2]; 2], u: f64, v: f64, w: f64) -> f64 {
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let uu = u * u * (3.0 - 2.0 * u);
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let vv = v * v * (3.0 - 2.0 * v);
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let ww = w * w * (3.0 - 2.0 * w);
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let mut accum = 0.0;
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for i in 0..2 {
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for j in 0..2 {
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for k in 0..2 {
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let ifl = i as f64;
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let jfl = j as f64;
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let kfl = k as f64;
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let weight_v = Vec3::new(u - ifl, v - jfl, w - kfl);
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accum += (ifl*uu + (1.0-ifl)*(1.0-uu))
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* (jfl*vv + (1.0-jfl)*(1.0-vv))
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* (kfl*ww + (1.0-kfl)*(1.0-ww))
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* (c[i][j][k]).dot(&weight_v);
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}
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}
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}
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accum
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}
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}
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