Glass material

src/main.rs

@@ -1,6 +1,6 @@
 use camera::Camera;
 use color::Color;
-use material::{Lambertian, Metal};
+use material::{Dielectric, Lambertian, Metal};
 
 use crate::{hittable_list::HittableList, sphere::Sphere, vec3::Point3};
 
@@ -15,21 +15,24 @@ mod camera;
 mod material;
 
 fn main() {
-    let ground = Lambertian {albedo: Color::new(0.8,0.8,0.0)};
-    let center = Lambertian {albedo: Color::new(0.1, 0.2, 0.5)};
-    let left = Metal {albedo: Color::new(0.8, 0.8, 0.8), fuzz: 0.3};
-    let right = Metal {albedo: Color::new(0.8, 0.6, 0.2), fuzz: 1.0};
+    let ground_mat = Lambertian {albedo: Color::new(0.8,0.8,0.0)};
+    let center_mat = Lambertian {albedo: Color::new(0.1, 0.2, 0.5)};
+    let left_mat = Dielectric { refraction_index: 1.5};
+    let bubble_mat = Dielectric { refraction_index: 1.0 / 1.5};
+    let right_mat = Metal {albedo: Color::new(0.8, 0.6, 0.2), fuzz: 1.0};
 
     let mut world = HittableList::new();
 
-    let ground = Sphere::new(Point3::new(0.0, -100.5, -1.0), 100.0, &ground);
-    let center = Sphere::new(Point3::new(0.0, 0.0, -1.2), 0.5, &center);
-    let left = Sphere::new(Point3::new(-1.0, 0.0, -1.0), 0.5, &left);
-    let right = Sphere::new(Point3::new(1.0, 0.0, -1.0), 0.5, &right);
+    let ground = Sphere::new(Point3::new(0.0, -100.5, -1.0), 100.0, &ground_mat);
+    let center = Sphere::new(Point3::new(0.0, 0.0, -1.2), 0.5, &center_mat);
+    let left = Sphere::new(Point3::new(-1.0, 0.0, -1.0), 0.5, &left_mat);
+    let bubble = Sphere::new(Point3::new(-1.0, 0.0, -1.0), 0.4, &bubble_mat);
+    let right = Sphere::new(Point3::new(1.0, 0.0, -1.0), 0.5, &right_mat);
 
     world.add(&ground);
     world.add(&center);
     world.add(&left);
+    world.add(&bubble);
     world.add(&right);
 
     let mut cam = Camera::new(16.0/9.0, 400);

src/material.rs

@@ -1,4 +1,6 @@
-use crate::{color::Color, hittable::HitRecord, ray::Ray, vec3::{random_unit_vector, reflect, unit_vector}};
+use rand::random;
+
+use crate::{color::Color, hittable::HitRecord, ray::Ray, vec3::{dot, random_unit_vector, reflect, refract, unit_vector}};
 
 pub trait Material {
 	fn scatter(&self, r_in: &Ray, rec: &HitRecord, attenuation: &mut Color, scattered: &mut Ray) -> bool;
@@ -36,3 +38,32 @@ impl Material for Metal {
 		true
 	}
 }
+
+pub struct Dielectric { pub refraction_index: f64 }
+impl Dielectric {
+	fn reflectance(cosine: f64, refraction_index: f64) -> f64 {
+		let r0 = (1.0 - refraction_index) / (1.0 + refraction_index);
+		let r0 = r0 * r0;
+		r0 + (1.0-r0) * (1.0 - cosine).powi(5)
+
+	}
+}
+impl Material for Dielectric {
+	fn scatter(&self, r_in: &Ray, rec: &HitRecord, attenuation: &mut Color, scattered: &mut Ray) -> bool {
+		*attenuation = Color::new(1.0, 1.0, 1.0);
+		let ri = if rec.front_face {1.0/self.refraction_index} else {self.refraction_index};
+
+		let unit_dir = unit_vector(r_in.dir());
+		let cos_theta = dot(-unit_dir, rec.normal).min(1.0);
+		let sin_theta = (1.0 - cos_theta*cos_theta).sqrt();
+
+		let direction = if ri * sin_theta > 1.0 || Self::reflectance(cos_theta, ri) > random() {
+			reflect(&unit_dir, &rec.normal)
+		} else {
+			refract(&unit_dir, &rec.normal, ri)
+		};
+
+		*scattered = Ray::new(rec.p, direction);
+		true
+	}
+}

src/vec3.rs

@@ -1,4 +1,4 @@
-use std::{fmt::Display, ops::{Add, AddAssign, Div, DivAssign, Index, IndexMut, Mul, MulAssign, Neg, RangeBounds, Sub}};
+use std::{cmp::min, fmt::Display, ops::{Add, AddAssign, Div, DivAssign, Index, IndexMut, Mul, MulAssign, Neg, RangeBounds, Sub}};
 use rand::{distributions::uniform::SampleRange, random, thread_rng, Rng};
 
 #[derive(Clone, Copy, Default)]
@@ -167,4 +167,11 @@ pub fn random_on_hemisphere(normal: Vec3) -> Vec3 {
 
 pub fn reflect(v: &Vec3, n: &Vec3) -> Vec3 {
 	*v - 2.0 * dot(*n, *v) * *n
+}
+
+pub fn refract(uv: &Vec3, n: &Vec3, etai_over_etat: f64) -> Vec3 {
+	let cos_theta = dot(- *uv, *n).min(1.0);
+	let r_out_perp = etai_over_etat * (*uv + cos_theta * *n);
+	let r_out_parallel = -(1.0 - r_out_perp.length_squared()).abs().sqrt() * *n;
+	r_out_parallel + r_out_perp
 }