1use rand::{rngs::ThreadRng, Rng};
2
3use crate::math::{Color, Vector3};
4
5pub fn write_color(pixel_color: Color, samples_per_pixel: u32) -> String {
6 let scale = 1.0 / samples_per_pixel as f64;
7 let pixel_color = pixel_color * scale;
8
9 let ir = (256.0 * clamp(pixel_color.x().sqrt(), 0.0, 0.999)) as i32;
10 let ig = (256.0 * clamp(pixel_color.y().sqrt(), 0.0, 0.999)) as i32;
11 let ib = (256.0 * clamp(pixel_color.z().sqrt(), 0.0, 0.999)) as i32;
12
13 format!("{ir} {ig} {ib}")
14}
15
16pub fn clamp(x: f64, min: f64, max: f64) -> f64 {
17 if x < min {
18 min
19 } else if x > max {
20 max
21 } else {
22 x
23 }
24}
25
26pub fn random_in_unit_sphere(rng: &mut ThreadRng) -> Vector3 {
27 use rand::prelude::*;
28
29 loop {
30 let p = Vector3::new(
31 rng.gen_range(-1.0..1.0),
32 rng.gen_range(-1.0..1.0),
33 rng.gen_range(-1.0..1.0),
34 );
35
36 if p.length_squared() < 1.0 {
37 return p;
38 }
39 }
40}
41
42pub fn random_unit_vector(rng: &mut ThreadRng) -> Vector3 {
43 random_in_unit_sphere(rng).unit_vector()
44}
45
46pub fn reflect(v: Vector3, n: Vector3) -> Vector3 {
47 v - 2.0 * v.dot(&n) * n
48}
49
50pub fn refract(uv: Vector3, n: Vector3, etai_over_etat: f64) -> Vector3 {
51 let cos_theta = (-uv).dot(&n).min(1.0);
52 let r_out_perp = etai_over_etat * (uv + cos_theta * n);
53 let r_out_parallel = -(1.0 - r_out_perp.length_squared()).abs().sqrt() * n;
54 r_out_perp + r_out_parallel
55}
56
57pub fn random_in_unit_disk(rng: &mut ThreadRng) -> Vector3 {
58 loop {
59 let p = Vector3::new(rng.gen_range(-1.0..1.0), rng.gen_range(-1.0..1.0), 0.0);
60 if p.length_squared() < 1.0 {
61 return p;
62 }
63 }
64}