Set up lighting calculations

ray-tracer/src/bin/sphere.rs

@@ -7,7 +7,7 @@ const SIZE: usize = 1000;
 fn main() {
     let canvas = Arc::new(RwLock::new(Canvas::new(SIZE, SIZE)));
     let mut sphere = Sphere::default();
-    sphere.set_transformation(shearing(1., 0., 0., 0., 0., 0.));
+    *sphere.transformation_mut() = shearing(1., 0., 0., 0., 0., 0.);
 
     let camera = Point::new(0., 1., -5.);
     let wall_z = 10.;

ray-tracer/src/types/color.rs

@@ -22,7 +22,6 @@ impl Color {
     pub fn blue(&self) -> f64 {
         self.0.2
     }
-
 }
 
 impl Default for Color {

ray-tracer/src/types/light.rs

@@ -0,0 +1,12 @@
+use super::{Color, Point};
+
+pub struct PointLight {
+    pub position: Point,
+    pub intensity: Color,
+}
+
+impl PointLight {
+    pub fn new(position: Point, intensity: Color) -> Self {
+        Self { position, intensity }
+    }
+}

ray-tracer/src/types/material.rs

@@ -0,0 +1,118 @@
+use super::{Color, Point, PointLight, Vector};
+
+#[derive(Debug, PartialEq)]
+pub struct Material {
+    pub color: Color,
+    pub ambient: f64,
+    pub diffuse: f64,
+    pub specular: f64,
+    pub shininess: f64,
+}
+
+impl Default for Material {
+    fn default() -> Self {
+        Self {
+            color: Color::new(1., 1., 1.),
+            ambient: 0.1,
+            diffuse: 0.9,
+            specular: 0.9,
+            shininess: 200.,
+        }
+    }
+}
+
+impl Material {
+    pub fn lighting(&self, light: &PointLight, position: &Point, eye: &Vector, normal: &Vector) -> Color {
+        let effective_color = self.color * light.intensity;
+
+        let light_v = (light.position - position).normalize();
+        let ambient = effective_color * self.ambient;
+
+        let light_dot_normal = light_v.dot(&normal);
+        let (diffuse, specular) = if light_dot_normal < 0. {
+            (Color::new(0., 0., 0.), Color::new(0., 0., 0.))
+        } else {
+            let diffuse = effective_color * self.diffuse * light_dot_normal;
+
+            let reflect_v = (-light_v).reflect(&normal);
+            let reflect_dot_eye = reflect_v.dot(&eye);
+
+            let specular = if reflect_dot_eye <= 0. {
+                Color::new(0., 0., 0.)
+            } else {
+                let factor = reflect_dot_eye.powf(self.shininess);
+                light.intensity * self.specular * factor
+            };
+
+            (diffuse, specular)
+        };
+
+        ambient + diffuse + specular
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::types::{Color, Point, PointLight, Vector};
+    use super::*;
+
+    #[test]
+    fn lighting_with_eye_between_light_and_surface() {
+        let m = Material::default();
+        let position = Point::default();
+
+        let eyev = Vector::new(0., 0., -1.);
+        let normalv = Vector::new(0., 0., -1.);
+        let light = PointLight::new(Point::new(0., 0., -10.), Color::new(1., 1., 1.));
+
+        assert_eq!(m.lighting(&light, &position, &eyev, &normalv), Color::new(1.9, 1.9, 1.9));
+    }
+
+    #[test]
+    fn lighting_with_eye_between_light_and_surface_eye_offset_45() {
+        let m = Material::default();
+        let position = Point::default();
+
+        let eyev = Vector::new(0., 2_f64.sqrt() / 2., -2_f64.sqrt() / 2.);
+        let normalv = Vector::new(0., 0., -1.);
+        let light = PointLight::new(Point::new(0., 0., -10.), Color::new(1., 1., 1.));
+
+        assert_eq!(m.lighting(&light, &position, &eyev, &normalv), Color::new(1., 1., 1.));
+    }
+
+    #[test]
+    fn lighting_with_eye_between_light_and_surface_light_offset_45() {
+        let m = Material::default();
+        let position = Point::default();
+
+        let eyev = Vector::new(0., 0., -1.);
+        let normalv = Vector::new(0., 0., -1.);
+        let light = PointLight::new(Point::new(0., 10., -10.), Color::new(1., 1., 1.));
+
+        assert_eq!(m.lighting(&light, &position, &eyev, &normalv), Color::new(0.7364, 0.7364, 0.7364));
+    }
+
+    #[test]
+    fn lighting_eye_in_path_of_reflection() {
+        let m = Material::default();
+        let position = Point::default();
+
+        let eyev = Vector::new(0., -2_f64.sqrt() / 2., -2_f64.sqrt() / 2.);
+        let normalv = Vector::new(0., 0., -1.);
+        let light = PointLight::new(Point::new(0., 10., -10.), Color::new(1., 1., 1.));
+
+        assert_eq!(m.lighting(&light, &position, &eyev, &normalv), Color::new(1.6364, 1.6364, 1.6364));
+    }
+
+    #[test]
+    fn lighting_with_light_behind_surface() {
+        let m = Material::default();
+        let position = Point::default();
+
+        let eyev = Vector::new(0., 0., -1.);
+        let normalv = Vector::new(0., 0., -1.);
+        let light = PointLight::new(Point::new(0., 0., 10.), Color::new(1., 1., 1.));
+
+        assert_eq!(m.lighting(&light, &position, &eyev, &normalv), Color::new(0.1, 0.1, 0.1));
+    }
+}

ray-tracer/src/types/mod.rs

@@ -1,6 +1,8 @@
 mod canvas;
 mod color;
 mod intersections;
+mod light;
+mod material;
 mod matrix;
 mod point;
 mod ray;
@@ -11,6 +13,8 @@ mod vector;
 pub use canvas::Canvas;
 pub use color::Color;
 pub use intersections::{Intersections, Intersection};
+pub use light::PointLight;
+pub use material::Material;
 pub use matrix::Matrix;
 pub use point::Point;
 pub use ray::Ray;

ray-tracer/src/types/point.rs

@@ -58,6 +58,20 @@ impl std::ops::Sub<&Point> for &Point {
     }
 }
 
+impl std::ops::Sub<Point> for &Point {
+    type Output = Vector;
+    fn sub(self, r: Point) -> Self::Output {
+        self - &r
+    }
+}
+
+impl std::ops::Sub<&Point> for Point {
+    type Output = Vector;
+    fn sub(self, r: &Point) -> Self::Output {
+        &self - r
+    }
+}
+
 impl std::ops::Sub<Point> for Point {
     type Output = Vector;
     fn sub(self, r: Point) -> Self::Output {

ray-tracer/src/types/ray.rs

@@ -172,7 +172,7 @@ mod tests {
     fn intersect_scaled_sphere_with_ray() {
         let r = Ray::new(Point::new(0., 0., -5.), Vector::new(0., 0., 1.));
         let mut s = Sphere::default();
-        s.set_transformation(scaling(2., 2., 2.));
+        *s.transformation_mut() = scaling(2., 2., 2.);
         let xs = r.intersect(&s);
         assert_eq!(xs.len(), 2);
         assert_eq!(xs[0].t, 3.);
@@ -183,7 +183,7 @@ mod tests {
     fn intersect_translated_sphere_with_ray() {
         let r = Ray::new(Point::new(0., 0., -5.), Vector::new(0., 0., 1.));
         let mut s = Sphere::default();
-        s.set_transformation(translation(5., 0., 0.));
+        *s.transformation_mut() = translation(5., 0., 0.);
         let xs = r.intersect(&s);
         assert_eq!(xs.len(), 0);
     }

ray-tracer/src/types/sphere.rs

@@ -1,9 +1,10 @@
-use crate::types::{Matrix, Point, Vector};
+use super::{Matrix, Point, Vector, Material };
 
 #[derive(Debug, PartialEq)]
 pub struct Sphere {
     origin: Point,
     transformation: Matrix,
+    material: Material,
 }
 
 impl Sphere {
@@ -11,8 +12,16 @@ impl Sphere {
         &self.transformation
     }
 
-    pub fn set_transformation(&mut self, m: Matrix) {
+    pub fn transformation_mut(&mut self) -> &mut Matrix{
-        self.transformation = m
+        &mut self.transformation
+    }
+
+    pub fn material(&self) -> &Material {
+        &self.material
+    }
+
+    pub fn material_mut(&mut self) -> &mut Material {
+        &mut self.material
     }
 
     pub fn normal_at(&self, world_point: &Point) -> Vector {
@@ -30,6 +39,7 @@ impl Default for Sphere {
         Self {
             origin: Point::new(0., 0., 0.),
             transformation: Matrix::identity(),
+            material: Default::default(),
         }
     }
 }
@@ -49,7 +59,7 @@ mod test {
     fn change_a_spheres_transformation() {
         let mut s = Sphere::default();
         let t = translation(2., 3., 4.);
-        s.set_transformation(t.clone());
+        *s.transformation_mut() = t.clone();
         assert_eq!(*s.transformation(), t);
     }
 
@@ -91,7 +101,7 @@ mod test {
     #[test]
     fn compute_normal_of_translated_sphere() {
         let mut s = Sphere::default();
-        s.set_transformation(translation(0., 1., 0.));
+        *s.transformation_mut() = translation(0., 1., 0.);
         let n = s.normal_at(&Point::new(0., 1.70711, -0.70711));
         assert_eq!(n, Vector::new(0., 0.70711, -0.70711));
     }
@@ -99,7 +109,7 @@ mod test {
     #[test]
     fn compute_normal_of_transformed_sphere() {
         let mut s = Sphere::default();
-        s.set_transformation(scaling(1., 0.5, 1.) * rotation_z(std::f64::consts::PI / 5.));
+        *s.transformation_mut() = scaling(1., 0.5, 1.) * rotation_z(std::f64::consts::PI / 5.);
         let n = s.normal_at(&Point::new(0., 2_f64.sqrt() / 2., -2_f64.sqrt() / 2.));
         assert_eq!(n, Vector::new(0., 0.97014, -0.24254));
     }