Implement Lambertian and Metal materials.

Fixed bug with Vec3::unit_vector().
Had to remove old example programs because Sphere::new() API changed to
allow materials.

rtiow/src/bin/tracer.rs

@@ -6,30 +6,20 @@ use rand::Rng;
 use rtiow::camera::Camera;
 use rtiow::hitable::Hit;
 use rtiow::hitable_list::HitableList;
+use rtiow::material::Lambertian;
+use rtiow::material::Metal;
 use rtiow::ray::Ray;
 use rtiow::sphere::Sphere;
 use rtiow::vec3::Vec3;
 
-fn random_in_unit_sphere() -> Vec3 {
-    let mut rng = rand::thread_rng();
-    let v = Vec3::new(1., 1., 1.);
-    loop {
-        let p = 2. * Vec3::new(
-            rng.gen_range::<f32>(0., 1.),
-            rng.gen_range::<f32>(0., 1.),
-            rng.gen_range::<f32>(0., 1.),
-        ) - v;
-        if p.squared_length() < 1. {
-            return p;
-        }
-    }
-}
-
-fn color(r: Ray, world: &Hit) -> Vec3 {
+fn color(r: Ray, world: &Hit, depth: usize) -> Vec3 {
     if let Some(rec) = world.hit(r, 0.001, std::f32::MAX) {
-        let target = rec.p + rec.normal + random_in_unit_sphere();
-        // 50% grey material
-        return 0.5 * color(Ray::new(rec.p, target - rec.p), world);
+        let scatter_response = rec.material.scatter(&r, &rec);
+        if depth < 50 && scatter_response.reflected {
+            return scatter_response.attenutation
+                * color(scatter_response.scattered, world, depth + 1);
+        }
+        return Default::default();
     }
 
     // No hit, choose color from background.
@@ -45,8 +35,26 @@ fn main() -> Result<(), std::io::Error> {
     let ns = 100;
     println!("P3\n{} {}\n255", nx, ny);
     let objects = vec![
-        Sphere::new(Vec3::new(0., 0., -1.), 0.5),
-        Sphere::new(Vec3::new(0., -100.5, -1.), 100.),
+        Sphere::new(
+            Vec3::new(0., 0., -1.),
+            0.5,
+            Box::new(Lambertian::new(Vec3::new(0.8, 0.3, 0.3))),
+        ),
+        Sphere::new(
+            Vec3::new(0., -100.5, -1.),
+            100.,
+            Box::new(Lambertian::new(Vec3::new(0.8, 0.8, 0.))),
+        ),
+        Sphere::new(
+            Vec3::new(1., 0., -1.),
+            0.5,
+            Box::new(Metal::new(Vec3::new(0.8, 0.6, 0.2), 0.2)),
+        ),
+        Sphere::new(
+            Vec3::new(-1., 0., -1.),
+            0.5,
+            Box::new(Metal::new(Vec3::new(0.8, 0.8, 0.8), 0.8)),
+        ),
     ];
     let cam = Camera::new2x1();
     let world = HitableList::new(objects.iter().map(|o| o).collect());
@@ -57,7 +65,7 @@ fn main() -> Result<(), std::io::Error> {
                 let u = (rng.gen_range::<f32>(0., 1.) + i as f32) / nx as f32;
                 let v = (rng.gen_range::<f32>(0., 1.) + j as f32) / ny as f32;
                 let r = cam.get_ray(u, v);
-                col = col + color(r, &world);
+                col = col + color(r, &world, 0);
             }
             col = col / ns as f32;
             // Gamma correct, use gamma 2 correction, which is 1/gamma where gamma=2 which is 1/2

rtiow/src/bin/tracer_anti_alias.rs

@@ -1,53 +0,0 @@
-extern crate rand;
-extern crate rtiow;
-
-use rand::Rng;
-
-use rtiow::camera::Camera;
-use rtiow::hitable::Hit;
-use rtiow::hitable_list::HitableList;
-use rtiow::ray::Ray;
-use rtiow::sphere::Sphere;
-use rtiow::vec3::Vec3;
-
-fn color(r: Ray, world: &Hit) -> Vec3 {
-    if let Some(rec) = world.hit(r, 0., std::f32::MAX) {
-        return (rec.normal + 1.) * 0.5;
-    }
-
-    // No hit, choose color from background.
-    let unit_direction = r.direction().unit_vector();
-    let t = 0.5 * (unit_direction.y + 1.);
-    Vec3::new(1., 1., 1.) * (1. - t) + Vec3::new(0.5, 0.7, 1.) * t
-}
-
-fn main() -> Result<(), std::io::Error> {
-    let mut rng = rand::thread_rng();
-    let nx = 200;
-    let ny = 100;
-    let ns = 100;
-    println!("P3\n{} {}\n255", nx, ny);
-    let objects = vec![
-        Sphere::new(Vec3::new(0., 0., -1.), 0.5),
-        Sphere::new(Vec3::new(0., -100.5, -1.), 100.),
-    ];
-    let cam = Camera::new2x1();
-    let world = HitableList::new(objects.iter().map(|o| o).collect());
-    for j in (0..ny).rev() {
-        for i in 0..nx {
-            let mut col: Vec3 = Default::default();
-            for _ in 0..ns {
-                let u = (rng.gen_range::<f32>(0., 1.) + i as f32) / nx as f32;
-                let v = (rng.gen_range::<f32>(0., 1.) + j as f32) / ny as f32;
-                let r = cam.get_ray(u, v);
-                col = col + color(r, &world);
-            }
-            col = col / ns as f32;
-            let ir = (255.99 * col[0]) as u32;
-            let ig = (255.99 * col[1]) as u32;
-            let ib = (255.99 * col[2]) as u32;
-            println!("{} {} {}", ir, ig, ib);
-        }
-    }
-    Ok(())
-}

rtiow/src/bin/tracer_material.rs

@@ -6,30 +6,20 @@ use rand::Rng;
 use rtiow::camera::Camera;
 use rtiow::hitable::Hit;
 use rtiow::hitable_list::HitableList;
+use rtiow::material::Lambertian;
+use rtiow::material::Metal;
 use rtiow::ray::Ray;
 use rtiow::sphere::Sphere;
 use rtiow::vec3::Vec3;
 
-fn random_in_unit_sphere() -> Vec3 {
-    let mut rng = rand::thread_rng();
-    let v = Vec3::new(1., 1., 1.);
-    loop {
-        let p = 2. * Vec3::new(
-            rng.gen_range::<f32>(0., 1.),
-            rng.gen_range::<f32>(0., 1.),
-            rng.gen_range::<f32>(0., 1.),
-        ) - v;
-        if p.squared_length() < 1. {
-            return p;
-        }
-    }
-}
-
-fn color(r: Ray, world: &Hit) -> Vec3 {
+fn color(r: Ray, world: &Hit, depth: usize) -> Vec3 {
     if let Some(rec) = world.hit(r, 0.001, std::f32::MAX) {
-        let target = rec.p + rec.normal + random_in_unit_sphere();
-        // 50% grey material
-        return 0.5 * color(Ray::new(rec.p, target - rec.p), world);
+        let scatter_response = rec.material.scatter(&r, &rec);
+        if depth < 50 && scatter_response.reflected {
+            return scatter_response.attenutation
+                * color(scatter_response.scattered, world, depth + 1);
+        }
+        return Default::default();
     }
 
     // No hit, choose color from background.
@@ -45,8 +35,26 @@ fn main() -> Result<(), std::io::Error> {
     let ns = 100;
     println!("P3\n{} {}\n255", nx, ny);
     let objects = vec![
-        Sphere::new(Vec3::new(0., 0., -1.), 0.5),
-        Sphere::new(Vec3::new(0., -100.5, -1.), 100.),
+        Sphere::new(
+            Vec3::new(0., 0., -1.),
+            0.5,
+            Box::new(Lambertian::new(Vec3::new(0.8, 0.3, 0.3))),
+        ),
+        Sphere::new(
+            Vec3::new(0., -100.5, -1.),
+            100.,
+            Box::new(Lambertian::new(Vec3::new(0.8, 0.8, 0.))),
+        ),
+        Sphere::new(
+            Vec3::new(1., 0., -1.),
+            0.5,
+            Box::new(Metal::new(Vec3::new(0.8, 0.6, 0.2), 0.2)),
+        ),
+        Sphere::new(
+            Vec3::new(-1., 0., -1.),
+            0.5,
+            Box::new(Metal::new(Vec3::new(0.8, 0.8, 0.8), 0.8)),
+        ),
     ];
     let cam = Camera::new2x1();
     let world = HitableList::new(objects.iter().map(|o| o).collect());
@@ -57,7 +65,7 @@ fn main() -> Result<(), std::io::Error> {
                 let u = (rng.gen_range::<f32>(0., 1.) + i as f32) / nx as f32;
                 let v = (rng.gen_range::<f32>(0., 1.) + j as f32) / ny as f32;
                 let r = cam.get_ray(u, v);
-                col = col + color(r, &world);
+                col = col + color(r, &world, 0);
             }
             col = col / ns as f32;
             // Gamma correct, use gamma 2 correction, which is 1/gamma where gamma=2 which is 1/2

rtiow/src/bin/tracer_multiple_spheres.rs

@@ -1,46 +0,0 @@
-extern crate rtiow;
-
-use rtiow::hitable::Hit;
-use rtiow::hitable_list::HitableList;
-use rtiow::ray::Ray;
-use rtiow::sphere::Sphere;
-use rtiow::vec3::Vec3;
-
-fn color(r: Ray, world: &Hit) -> Vec3 {
-    if let Some(rec) = world.hit(r, 0., std::f32::MAX) {
-        return (rec.normal + 1.) * 0.5;
-    }
-
-    // No hit, choose color from background.
-    let unit_direction = r.direction().unit_vector();
-    let t = 0.5 * (unit_direction.y + 1.);
-    Vec3::new(1., 1., 1.) * (1. - t) + Vec3::new(0.5, 0.7, 1.) * t
-}
-
-fn main() -> Result<(), std::io::Error> {
-    let nx = 200;
-    let ny = 100;
-    println!("P3\n{} {}\n255", nx, ny);
-    let lower_left_corner = Vec3::new(-2., -1., -1.);
-    let horizontal = Vec3::new(4., 0., 0.);
-    let vertical = Vec3::new(0., 2., 0.);
-    let origin: Vec3 = Default::default();
-    let objects = vec![
-        Sphere::new(Vec3::new(0., 0., -1.), 0.5),
-        Sphere::new(Vec3::new(0., -100.5, -1.), 100.),
-    ];
-    let world = HitableList::new(objects.iter().map(|o| o).collect());
-    for j in (0..ny).rev() {
-        for i in 0..nx {
-            let u = i as f32 / nx as f32;
-            let v = j as f32 / ny as f32;
-            let r = Ray::new(origin, lower_left_corner + horizontal * u + vertical * v);
-            let col = color(r, &world);
-            let ir = (255.99 * col[0]) as u32;
-            let ig = (255.99 * col[1]) as u32;
-            let ib = (255.99 * col[2]) as u32;
-            println!("{} {} {}", ir, ig, ib);
-        }
-    }
-    Ok(())
-}

rtiow/src/hitable.rs

@@ -1,11 +1,12 @@
+use material::Material;
 use ray::Ray;
 use vec3::Vec3;
 
-#[derive(Copy, Clone)]
-pub struct HitRecord {
+pub struct HitRecord<'m> {
     pub t: f32,
     pub p: Vec3,
     pub normal: Vec3,
+    pub material: &'m Material,
 }
 
 pub trait Hit {

rtiow/src/lib.rs

@@ -1,6 +1,7 @@
 pub mod camera;
 pub mod hitable;
 pub mod hitable_list;
+pub mod material;
 pub mod ray;
 pub mod sphere;
 pub mod vec3;

rtiow/src/material.rs

@@ -0,0 +1,81 @@
+extern crate rand;
+use self::rand::Rng;
+
+use hitable::HitRecord;
+use ray::Ray;
+use vec3::dot;
+use vec3::Vec3;
+
+fn random_in_unit_sphere() -> Vec3 {
+    let mut rng = rand::thread_rng();
+    let v = Vec3::new(1., 1., 1.);
+    loop {
+        let p = 2. * Vec3::new(
+            rng.gen_range::<f32>(0., 1.),
+            rng.gen_range::<f32>(0., 1.),
+            rng.gen_range::<f32>(0., 1.),
+        ) - v;
+        if p.squared_length() < 1. {
+            return p;
+        }
+    }
+}
+
+pub struct ScatterResponse {
+    pub scattered: Ray,
+    pub attenutation: Vec3,
+    pub reflected: bool,
+}
+
+pub trait Material {
+    fn scatter(&self, r_in: &Ray, rec: &HitRecord) -> ScatterResponse;
+}
+
+pub struct Lambertian {
+    albedo: Vec3,
+}
+
+impl Lambertian {
+    pub fn new(albedo: Vec3) -> Lambertian {
+        Lambertian { albedo }
+    }
+}
+
+impl Material for Lambertian {
+    fn scatter(&self, _r_in: &Ray, rec: &HitRecord) -> ScatterResponse {
+        let target = rec.p + rec.normal + random_in_unit_sphere();
+        ScatterResponse {
+            attenutation: self.albedo,
+            scattered: Ray::new(rec.p, target - rec.p),
+            reflected: true,
+        }
+    }
+}
+
+pub struct Metal {
+    albedo: Vec3,
+    fuzzy: f32,
+}
+
+fn reflect(v: Vec3, n: Vec3) -> Vec3 {
+    v - 2. * dot(v, n) * n
+}
+
+impl Metal {
+    pub fn new(albedo: Vec3, fuzzy: f32) -> Metal {
+        let fuzzy = fuzzy.min(1.);
+        Metal { albedo, fuzzy }
+    }
+}
+
+impl Material for Metal {
+    fn scatter(&self, r_in: &Ray, rec: &HitRecord) -> ScatterResponse {
+        let reflected = reflect(r_in.direction().unit_vector(), rec.normal);
+        let scattered = Ray::new(rec.p, reflected + self.fuzzy * random_in_unit_sphere());
+        ScatterResponse {
+            scattered,
+            attenutation: self.albedo,
+            reflected: dot(scattered.direction(), rec.normal) > 0.,
+        }
+    }
+}

rtiow/src/sphere.rs

@@ -1,18 +1,23 @@
 use hitable::Hit;
 use hitable::HitRecord;
+use material::Material;
 use ray::Ray;
 use vec3::dot;
 use vec3::Vec3;
 
-#[derive(Copy, Clone, Default)]
 pub struct Sphere {
     center: Vec3,
     radius: f32,
+    material: Box<Material>,
 }
 
 impl Sphere {
-    pub fn new(center: Vec3, radius: f32) -> Sphere {
-        Sphere { center, radius }
+    pub fn new(center: Vec3, radius: f32, material: Box<Material>) -> Sphere {
+        Sphere {
+            center,
+            radius,
+            material,
+        }
     }
 }
 
@@ -31,6 +36,7 @@ impl Hit for Sphere {
                     t: temp,
                     p,
                     normal: (p - self.center) / self.radius,
+                    material: &*self.material,
                 });
             }
             let temp = (-b + (b * b - a * c).sqrt()) / a;
@@ -40,6 +46,7 @@ impl Hit for Sphere {
                     t: temp,
                     p,
                     normal: (p - self.center) / self.radius,
+                    material: &*self.material,
                 });
             }
         }

rtiow/src/vec3.rs

@@ -40,12 +40,7 @@ impl Vec3 {
     }
 
     pub fn unit_vector(self) -> Vec3 {
-        let k = 1. / self.length();
-        Vec3 {
-            x: self.x / k,
-            y: self.y / k,
-            z: self.z / k,
-        }
+        self / self.length()
     }
 
     pub fn make_unit_vector(&mut self) {