Add multiple light support.

rtchallenge/examples/eoc7.rs

@@ -95,7 +95,7 @@ fn main() -> Result<()> {
     };
 
     let mut world = World::default();
-    world.light = Some(light);
+    world.lights = vec![light];
     world.objects = vec![floor, left_wall, right_wall, middle, right, left];
 
     let image = camera.render(&world);

rtchallenge/examples/eoc8.rs

@@ -35,7 +35,10 @@ fn main() -> Result<()> {
     let height = 1440;
     let light_position = Tuple::point(-10., 10., -10.);
     let light_color = WHITE;
-    let light = PointLight::new(light_position, light_color);
+    let light1 = PointLight::new(light_position, light_color);
+    let light_position = Tuple::point(10., 10., -10.);
+    let light_color = Color::new(0.0, 0.0, 1.0);
+    let light2 = PointLight::new(light_position, light_color);
     let mut camera = Camera::new(width, height, PI / 4.);
     let from = Tuple::point(0., 1.5, -5.);
     let to = Tuple::point(0., 1., 0.);
@@ -82,7 +85,7 @@ fn main() -> Result<()> {
     let mut right = Sphere::default();
     right.set_transform(Matrix4x4::translation(1.5, 0.5, -0.5) * Matrix4x4::scaling(0.5, 0.5, 0.5));
     right.material = Material {
-        color: Color::new(0.5, 1., 0.1),
+        color: Color::new(1., 1., 1.),
         diffuse: 0.7,
         specular: 0.3,
         ..Material::default()
@@ -100,7 +103,7 @@ fn main() -> Result<()> {
     };
 
     let mut world = World::default();
-    world.light = Some(light);
+    world.lights = vec![light1, light2];
     world.objects = vec![floor, left_wall, right_wall, middle, right, left];
 
     let image = camera.render(&world);

rtchallenge/src/spheres.rs

@@ -9,7 +9,6 @@ use crate::{
 #[derive(Debug, PartialEq, Clone)]
 /// Sphere represents the unit-sphere (radius of unit 1.) at the origin 0., 0., 0.
 pub struct Sphere {
-    // TODO(wathiede): cache inverse to speed up intersect.
     transform: Matrix4x4,
     inverse_transform: Matrix4x4,
     pub material: Material,

rtchallenge/src/world.rs

@@ -6,7 +6,7 @@ use crate::{
     rays::Ray,
     spheres::{intersect, Sphere},
     tuples::{Color, Tuple},
-    BLACK, WHITE,
+    Float, BLACK, WHITE,
 };
 
 /// World holds all drawable objects and the light(s) that illuminate them.
@@ -17,13 +17,12 @@ use crate::{
 ///
 /// let w = World::default();
 /// assert!(w.objects.is_empty());
-/// assert_eq!(w.light, None);
+/// assert_eq!(w.lights.len(), 0);
 /// ```
 
 #[derive(Clone, Debug, Default)]
 pub struct World {
-    // TODO(wathiede): make this a list of abstract Light traits.
-    pub light: Option<PointLight>,
+    pub lights: Vec<PointLight>,
     pub objects: Vec<Sphere>,
 }
 
@@ -36,7 +35,7 @@ impl World {
     ///
     /// let w = World::test_world();
     /// assert_eq!(w.objects.len(), 2);
-    /// assert!(w.light.is_some());
+    /// assert!(!w.lights.is_empty());
     /// ```
     pub fn test_world() -> World {
         let light = PointLight::new(Tuple::point(-10., 10., -10.), WHITE);
@@ -50,7 +49,7 @@ impl World {
         let mut s2 = Sphere::default();
         s2.set_transform(Matrix4x4::scaling(0.5, 0.5, 0.5));
         World {
-            light: Some(light),
+            lights: vec![light],
             objects: vec![s1, s2],
         }
     }
@@ -110,7 +109,7 @@ impl World {
     ///
     /// // Shading an intersection from the inside.
     /// let mut w = World::test_world();
-    /// w.light = Some(PointLight::new(Tuple::point(0., 0.25, 0.), WHITE));
+    /// w.lights = vec![PointLight::new(Tuple::point(0., 0.25, 0.), WHITE)];
     /// let r = Ray::new(Tuple::point(0., 0., 0.), Tuple::vector(0., 0., 1.));
     /// let s = &w.objects[1];
     /// let i = Intersection::new(0.5, &s);
@@ -120,7 +119,7 @@ impl World {
     ///
     /// // Shading with an intersection in shadow.
     /// let mut w = World::default();
-    /// w.light = Some(PointLight::new(Tuple::point(0., 0., -10.), WHITE));
+    /// w.lights = vec![PointLight::new(Tuple::point(0., 0., -10.), WHITE)];
     /// let s1 = Sphere::default();
     /// let mut s2 = Sphere::default();
     /// s2.set_transform(Matrix4x4::translation(0., 0., 10.));
@@ -132,17 +131,21 @@ impl World {
     /// assert_eq!(c, Color::new(0.1, 0.1, 0.1));
     /// ```
     pub fn shade_hit(&self, comps: &PrecomputedData) -> Color {
-        // TODO(wathiede): support multiple light sources by iterating over all
-        // the light sources and summing the calls to lighting.
-        let shadowed = self.is_shadowed(comps.over_point);
-        lighting(
-            &comps.object.material,
-            &self.light.as_ref().expect("World has no lights"),
-            comps.over_point,
-            comps.eyev,
-            comps.normalv,
-            shadowed,
-        )
+        let c = self
+            .lights
+            .iter()
+            .fold(Color::new(0., 0., 0.), |acc, light| {
+                let shadowed = self.is_shadowed(comps.over_point, light);
+                acc + lighting(
+                    &comps.object.material,
+                    light,
+                    comps.over_point,
+                    comps.eyev,
+                    comps.normalv,
+                    shadowed,
+                )
+            });
+        c / self.lights.len() as Float
     }
     /// Compute color for given ray fired at the world.
     ///
@@ -203,28 +206,24 @@ impl World {
     /// };
     ///
     /// let w = World::test_world();
+    /// let light = &w.lights[0];
     ///
     /// // There is no shadow when nothing is collinear with point and light.
     /// let p = Tuple::point(0.,10.,0.);
-    /// assert_eq!(w.is_shadowed(p), false);
+    /// assert_eq!(w.is_shadowed(p,light), false);
     ///
     /// // There shadow when an object is between the point and the light.
     /// let p = Tuple::point(10.,-10.,10.);
-    /// assert_eq!(w.is_shadowed(p), true);
+    /// assert_eq!(w.is_shadowed(p,light), true);
     ///
     /// // There is no shadow when an object is behind the light.
     /// let p = Tuple::point(-20.,20.,-20.);
-    /// assert_eq!(w.is_shadowed(p), false);
+    /// assert_eq!(w.is_shadowed(p,light), false);
     ///
     /// // There is no shadow when an object is behind the point.
     /// let p = Tuple::point(-2.,2.,-2.);
-    /// assert_eq!(w.is_shadowed(p), false);
-    pub fn is_shadowed(&self, point: Tuple) -> bool {
-        // TODO(wathiede): how to make this multi light aware?
-        let light = self
-            .light
-            .as_ref()
-            .expect("cannot compute is_shadowed in world with no light");
+    /// assert_eq!(w.is_shadowed(p,light), false);
+    pub fn is_shadowed(&self, point: Tuple, light: &PointLight) -> bool {
         let v = light.position - point;
         let distance = v.magnitude();
         let direction = v.normalize();