1 files changed, 62 insertions, 2 deletions
diff --git a/src/material.rs b/src/material.rs
index 3cbbb4a..42e8d0c 100644
--- a/src/material.rs
+++ b/src/material.rs
@@ -1,8 +1,9 @@
-use cgmath::Vector3;
+use cgmath::prelude::*;
+use cgmath::{Vector3, vec3, dot};
 use rand::prelude::*;
 use crate::ray::{Ray, NextRay};
 use crate::hittable::Hit;
-use crate::random::random_unit_vector;
+use crate::utils::{random_unit_vector, random_in_unit_sphere, reflect, refract, schlick};
 
 pub trait Material {
     fn scatter(&self, rng: &mut ThreadRng, ray: &Ray, hit: &Hit) -> Option<NextRay>;
@@ -24,3 +25,62 @@ impl Material for Lambertian {
         Some(NextRay::new(self.albedo, Ray::new(hit.p, scatter_direction)))
     }
 }
+
+pub struct Metal {
+    pub albedo: Vector3<f64>,
+    pub fuzz: f64
+}
+
+impl Metal {
+    pub fn new(albedo: Vector3<f64>, f: f64) -> Metal {
+        let fuzz = if f < 1.0 { f } else { 1.0 };
+        Metal { albedo, fuzz }
+    }
+}
+
+impl Material for Metal {
+    fn scatter(&self, rng: &mut ThreadRng, ray: &Ray, hit: &Hit) -> Option<NextRay> {
+        let reflected = reflect(&ray.dir.normalize(), &hit.normal);
+        let scattered = Ray::new(hit.p, reflected + self.fuzz * random_in_unit_sphere(rng));
+        if dot(scattered.dir, hit.normal) > 0.0 {
+            Some(NextRay::new(self.albedo, scattered))
+        } else {
+            None
+        }
+    }
+}
+
+pub struct Dielectric {
+    pub ref_idx: f64
+}
+
+impl Dielectric {
+    pub fn new(ref_idx: f64) -> Dielectric {
+        Dielectric { ref_idx }
+    }
+}
+
+impl Material for Dielectric {
+    fn scatter(&self, rng: &mut ThreadRng, ray: &Ray, hit: &Hit) -> Option<NextRay> {
+        let attenuation = vec3(1.0, 1.0, 1.0);
+        let etai_over_etat = if hit.front_face { 1.0 / self.ref_idx } else { self.ref_idx };
+
+        let unit_direction = ray.dir.normalize();
+        let cos_theta = f64::min(dot(-unit_direction, hit.normal), 1.0);
+        let sin_theta = (1.0 - cos_theta*cos_theta).sqrt();
+
+        if etai_over_etat * sin_theta > 1.0 {
+            let reflected = reflect(&unit_direction, &hit.normal);
+            return Some(NextRay::new(attenuation, Ray::new(hit.p, reflected)))
+        }
+
+        let reflect_prob = schlick(cos_theta, etai_over_etat);
+        if rng.gen::<f64>() < reflect_prob {
+            let reflected = reflect(&unit_direction, &hit.normal);
+            return Some(NextRay::new(attenuation, Ray::new(hit.p, reflected)))
+        }
+
+        let refracted = refract(&unit_direction, &hit.normal, etai_over_etat);
+        Some(NextRay::new(attenuation, Ray::new(hit.p, refracted)))
+    }
+}