2 files changed, 43 insertions(+), 8 deletions(-)

M src/main.rs
M src/vec3.rs

@@ 35,9 35,14 @@ fn hit_sphere(center: &Point3, radius: f64, r: &Ray) -> f64 {
     }
 }
 
-fn ray_color(r: &Ray, world: &dyn Hittable) -> Color {
-    if let Some(rec) = world.hit(r, 0.0, INFINITY) {
-        return 0.5 * (rec.normal + Color::new(1.0, 1.0, 1.0));
+fn ray_color(r: &Ray, world: &dyn Hittable, depth: isize) -> Color {
+    // If we've exceeded the ray bounce limit, no more light is gathered.
+    if depth <= 0 {
+        return Color::default();
+    }
+    if let Some(rec) = world.hit(r, 0.001, INFINITY) {
+        let target = rec.p + rec.normal + random_unit_vector();
+        return 0.5 * ray_color(&Ray::new(&rec.p, &(target - rec.p)), world, depth - 1);
     }
     let unit_direction = unit_vector(r.direction());
     let t = 0.5 * (unit_direction.y() + 1.0);


@@ 51,9 56,10 @@ fn main() {
     // Image
     let aspect_ratio = 16.0 / 9.0;
     let image_width = 400;
-    // let image_width = 1600;
+    let image_width = 1600;
     let image_height = (image_width as f64 / aspect_ratio) as i32;
     let samples_per_pixel = 100;
+    let max_depth = 50;
 
     // World
     let mut world = HittableList::empty();


@@ 75,7 81,7 @@ fn main() {
                 let u = (i as f64 + random_double()) / (image_width - 1) as f64;
                 let v = (j as f64 + random_double()) / (image_height - 1) as f64;
                 let r = cam.get_ray(u, v);
-                pixel_color += ray_color(&r, &world);
+                pixel_color += ray_color(&r, &world, max_depth);
             }
             write_color(&mut handle, pixel_color, samples_per_pixel);
         }

@@ 1,3 1,6 @@
+use crate::{random_double, random_double_range};
+use std::ops::Range;
+
 #[derive(Debug, Clone, Copy)]
 pub struct Vec3 {
     e: [f64; 3],


@@ 28,6 31,18 @@ impl Vec3 {
     pub fn length_squared(&self) -> f64 {
         self.e[0] * self.e[0] + self.e[1] * self.e[1] + self.e[2] * self.e[2]
     }
+
+    pub fn random() -> Self {
+        Self::new(random_double(), random_double(), random_double())
+    }
+
+    pub fn random_range(r: Range<f64>) -> Self {
+        Self::new(
+            random_double_range(r.clone()),
+            random_double_range(r.clone()),
+            random_double_range(r.clone()),
+        )
+    }
 }
 
 impl std::ops::Neg for &Vec3 {


@@ 170,9 185,9 @@ pub fn write_color(out: &mut impl std::io::Write, pixel_color: Color, samples_pe
 
     // Divide the color by the number of samples.
     let scale = 1.0 / samples_per_pixel as f64;
-    r *= scale;
-    g *= scale;
-    b *= scale;
+    r = (scale * r).sqrt();
+    g = (scale * g).sqrt();
+    b = (scale * b).sqrt();
 
     write!(
         out,


@@ 183,3 198,17 @@ pub fn write_color(out: &mut impl std::io::Write, pixel_color: Color, samples_pe
     )
     .unwrap();
 }
+
+pub fn random_in_unit_sphere() -> Vec3 {
+    loop {
+        let p = Vec3::random_range(-1.0..1.0);
+        if p.length_squared() >= 1.0 {
+            continue;
+        }
+        return p;
+    }
+}
+
+pub fn random_unit_vector() -> Vec3 {
+    unit_vector(random_in_unit_sphere())
+}