triangle

Cargo.lock

@@ -14,6 +14,37 @@ version = "1.0.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "9555578bc9e57714c812a1f84e4fc5b4d21fcb063490c624de019f7464c91268"
 
+[[package]]
+name = "crossbeam-deque"
+version = "0.8.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9dd111b7b7f7d55b72c0a6ae361660ee5853c9af73f70c3c2ef6858b950e2e51"
+dependencies = [
+ "crossbeam-epoch",
+ "crossbeam-utils",
+]
+
+[[package]]
+name = "crossbeam-epoch"
+version = "0.9.18"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5b82ac4a3c2ca9c3460964f020e1402edd5753411d7737aa39c3714ad1b5420e"
+dependencies = [
+ "crossbeam-utils",
+]
+
+[[package]]
+name = "crossbeam-utils"
+version = "0.8.21"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d0a5c400df2834b80a4c3327b3aad3a4c4cd4de0629063962b03235697506a28"
+
+[[package]]
+name = "either"
+version = "1.15.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "48c757948c5ede0e46177b7add2e67155f70e33c07fea8284df6576da70b3719"
+
 [[package]]
 name = "getrandom"
 version = "0.3.3"
@@ -99,6 +130,27 @@ name = "ray-trace-w1"
 version = "0.1.0"
 dependencies = [
  "rand",
+ "rayon",
+]
+
+[[package]]
+name = "rayon"
+version = "1.11.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "368f01d005bf8fd9b1206fb6fa653e6c4a81ceb1466406b81792d87c5677a58f"
+dependencies = [
+ "either",
+ "rayon-core",
+]
+
+[[package]]
+name = "rayon-core"
+version = "1.13.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "22e18b0f0062d30d4230b2e85ff77fdfe4326feb054b9783a3460d8435c8ab91"
+dependencies = [
+ "crossbeam-deque",
+ "crossbeam-utils",
 ]
 
 [[package]]

Cargo.toml

@@ -5,3 +5,4 @@ edition = "2024"
 
 [dependencies]
 rand = "0.9.2"  # 使用最新稳定版
+rayon = "1.11.0"

src/camera.rs

@@ -1,5 +1,7 @@
 use std::fs::File;
 use std::io::{BufWriter};
+use std::sync::{RwLock};
+use std::time::Instant;
 
 use crate::hittable::HittableList;
 use crate::math_utils::{clamp, degrees_to_radians, random_in_unit_disk};
@@ -7,6 +9,7 @@ use crate::ppm_writer::PPMWriter;
 use crate::types_defined::{Camera, Color, HitRecord, Point, Ray, Vec3};
 use rand::rngs::ThreadRng;
 use rand::{Rng, rng};
+use rayon::iter::{IntoParallelIterator, ParallelIterator};
 use crate::material::{Material, MaterialKind};
 
 impl<'a> Camera<'a> {
@@ -70,8 +73,8 @@ impl<'a> Camera<'a> {
             // viewport_width,
             // viewport_height,
             center,
-            look_at,
-            v_up,
+            // look_at,
+            // v_up,
             // focal_length,
             // viewport_u,
             // viewport_v,
@@ -90,6 +93,10 @@ impl<'a> Camera<'a> {
 
     pub fn render(&mut self, world: &HittableList) {
         // let mut img_content = format!("P3\n{} {}\n255\n", self.image_width, self.image_height);
+        let start = Instant::now();
+        
+        
+        
         
         for j in 0..self.image_height {
             // if j % 10 == 0 {
@@ -97,16 +104,25 @@ impl<'a> Camera<'a> {
             // }
 
             for i in 0..self.image_width {
-                // color
-                let mut color = Color::new(0.0, 0.0, 0.0);
-                let rng = &mut rng();
-                for _ in 0..self.sample_times {
-                    let r = self.get_ray(i, j);
-                    let sample_color = self.ray_color(&r, self.reflect_depth, world);
-                    color = color + sample_color;
-                }
-                // color * each sample color
-                color = color * (1.0 / self.sample_times as f32);
+                
+                let sample_color: Vec3 = (0..self.sample_times)
+                    .into_par_iter()
+                    .map(|_| {
+                        let r = self.get_ray(i, j);
+                        return self.ray_color_sync(&r, self.reflect_depth, RwLock::new(world));
+                    }).sum();
+                let color: Vec3 = sample_color * (1.0 / self.sample_times as f32);
+
+
+                // // color
+                // let mut color = Color::new(0.0, 0.0, 0.0);
+                // for _ in 0..self.sample_times {
+                //     let r = self.get_ray(i, j);
+                //     let sample_color = self.ray_color(&r, self.reflect_depth, world);
+                //     color = color + sample_color;
+                // }
+                // // color * each sample color
+                // color = color * (1.0 / self.sample_times as f32);
 
                 // clamp color rgb
                 let color_clamped = Color::new(
@@ -120,7 +136,8 @@ impl<'a> Camera<'a> {
         }
 
         let  _ = self.ppm_file_writer.finish();
-
+        let end = Instant::now();
+        println!("================[{}mils]=====================", end.duration_since(start).as_millis())
         // img_content
     }
 
@@ -198,9 +215,64 @@ impl<'a> Camera<'a> {
         (1.0 - a) * Color::new(1.0, 1.0, 1.0) + a * Color::new(0.5, 0.7, 1.0)
     }
 
+
+    fn ray_color_sync(&self, ray: &Ray, depth: i8, world: RwLock<&HittableList>) -> Vec3 {
+
+        // 反射次数
+        if depth <= 0 {
+            return Vec3::new(0.0, 0.0, 0.0);
+        }
+
+        // 限制出射光线的角度（0.001经验值）
+        let hit_record = &mut HitRecord{
+            t: 0.0,
+            p: Vec3::new(0.0, 0.0, 0.0),
+            normal: Vec3::new(0.0, 0.0, 0.0),
+            front_face: false,
+            material: None,
+        };
+        let hit = world.read().unwrap().hit(&ray, 0.001, f32::MAX, hit_record);
+        if hit {
+            let hit_m = &hit_record.material;
+            let hc = &mut HitRecord{
+                t: hit_record.t,
+                p: hit_record.p,
+                normal: hit_record.normal,
+                front_face: hit_record.front_face,
+                material: None,
+            };
+            let hit_c = match hit_m {
+                Some(mk) => {
+                    match mk {
+                        // MaterialKind::Lambertian(l) => l.albedo,
+                        MaterialKind::Lambertian(l) => self.scatter_color_sync(ray, hc, l, depth, world),
+                        MaterialKind::Metal(m) => self.scatter_color_sync(ray, hc, m, depth, world),
+                        MaterialKind::Dielectric(d) => self.scatter_color_sync(ray, hc, d, depth, world)
+                    }
+                },
+                None => {
+                    if hit_record.t >= 0.0 {
+                        let diffuse_vec = Vec3::random_unit();
+                        let lambertian_vec = diffuse_vec + hit_record.normal;
+                        0.5 * self.ray_color_sync(&Ray::new(ray.point, lambertian_vec), depth - 1, world)
+                    } else {
+                        Color::new(0.0, 0.0, 0.0)
+                    }
+                }
+            };
+            return hit_c;
+        }
+
+        // v / |v|
+        let unit_direction = ray.direction / ray.direction.length();
+        let a = 0.5 * (unit_direction.y + 1.0);
+        // return background color.
+        (1.0 - a) * Color::new(1.0, 1.0, 1.0) + a * Color::new(0.5, 0.7, 1.0)
+    }
+
     // -> [x, y, 0]
     fn random_square(&self, rng: &mut ThreadRng) -> Vec3 {
-        Vec3::new(rng.gen_range(-0.5..0.1), rng.gen_range(-0.5..0.1), 0.0)
+        Vec3::new(rng.random_range(-0.5..0.1), rng.random_range(-0.5..0.1), 0.0)
     }
 
 
@@ -231,6 +303,33 @@ impl<'a> Camera<'a> {
         }
     }
     
+    fn scatter_color_sync(
+        &self,
+        ray: &Ray,
+        hc: &mut HitRecord,
+        material: &impl Material,
+        depth: i8,
+        world: RwLock<&HittableList>,
+    ) -> Color {
+        let mut scatted = Ray::new(Point::new(0.0, 0.0, 0.0), Vec3::random());
+        let mut attenuation = Color::new(1.0, 1.0, 1.0);
+        if material.scatter(ray, hc, &mut attenuation, &mut scatted) {
+            let r_c = self.ray_color_sync(&scatted, depth - 1, world);
+            let sc_color = Vec3::new(
+                attenuation.x * r_c.x,
+                attenuation.y * r_c.y,
+                attenuation.z * r_c.z,
+            );
+            let color = Color::new(sc_color.x, sc_color.y, sc_color.z);
+            // if near_zero(color) {
+            //     println!("near zero: {:?}", scatted.direction);
+            // }
+            color
+        } else {
+            Color::new(0.0, 0.0, 0.0)
+        }
+    }
+
 }
 
 

src/hittable.rs

@@ -2,7 +2,7 @@ use crate::material::MaterialKind;
 use crate::math_utils::{front_face_normal, is_front_face};
 use crate::types_defined::{HitRecord, Ray, Vec3};
 
-pub trait Hittable {
+pub trait Hittable: Send + Sync {
     fn hit(&self, r: &Ray, t_min: f32, t_max: f32, hit_record: &mut HitRecord) -> bool;
 }
 

src/main.rs

@@ -1,9 +1,12 @@
 use std::fs::File;
 use std::io::BufWriter;
 
+use rand::{rng, Rng};
+
 use crate::hittable::HittableList;
 use crate::material::{Dielectric, Lambertian, MaterialKind, Metal};
 use crate::ppm_writer::PPMWriter;
+use crate::triangle::Triangle;
 use crate::types_defined::{Camera, Color, Point, Sphere, Vec3};
 mod camera;
 mod color;
@@ -15,6 +18,7 @@ mod vec3;
 mod math_utils;
 mod ppm_writer;
 mod material;
+mod triangle;
 
 fn main() {
     camera_render();
@@ -22,10 +26,10 @@ fn main() {
 
 fn camera_render() {
 
-    let fov: f32 = 60.;
-    let scale = 2;
-    let width: i32 = 800/scale;
-    let height: i32 = 600/scale;
+    let fov: f32 = 90.;
+    let scale = 1;
+    let width: i32 = 1920/scale;
+    let height: i32 = 1080/scale;
     let sample_times = 20;
     let reflect_depth = 20;
 
@@ -44,7 +48,7 @@ fn camera_render() {
         fov,
         width,
         width as f32 / height as f32,
-        Point::new(-0.0, 0.0, 0.0),
+        Point::new(-0.0, 5.0, 5.0),
         Point::new(0.0, 0.0, -1.0),
         Vec3::new(0., 1., 0.),
         sample_times,
@@ -57,23 +61,73 @@ fn camera_render() {
     // world objects(spheres)
     let mut world = HittableList::new();
 
-    let plane_m = Some(MaterialKind::Lambertian(Lambertian{albedo: Color::new(0.899, 0.899, 0.999)}));
-    // let plane2_m = Some(MaterialKind::Metal(Metal{albedo: Color::new(0.784,0.784,0.784)}));
-    let center_m = Some(MaterialKind::Lambertian(Lambertian{albedo: Color::new(0.2, 0.5, 0.5)}));
-    let left_m = Some(MaterialKind::Metal(Metal{albedo: Color::new(0.799, 0.599, 0.799), fuzz: 0.0005}));
-    let left_behind_m = Some(MaterialKind::Lambertian(Lambertian{albedo: Color::new(0.799, 0.599, 0.599)}));
-    let right_m = Some(MaterialKind::Metal(Metal{albedo: Color::new(0.8, 0.6, 0.2), fuzz: 0.003}));
-    // 折射率 1.33
-    let left_dia_m = Some(MaterialKind::Dielectric(Dielectric{albedo: Color::new(0.8, 0.6, 0.2), refraction_index: 1.00 / 1.33}));
-    let left_dia_small_m = Some(MaterialKind::Dielectric(Dielectric{albedo: Color::new(0.8, 0.6, 0.2), refraction_index: 1.00 / 2.5}));
+    let plane_m = Some(MaterialKind::Lambertian(Lambertian{albedo: Color::new(0.508, 0.508, 0.508)}));
+    // // let plane2_m = Some(MaterialKind::Metal(Metal{albedo: Color::new(0.784,0.784,0.784)}));
+    // let center_m = Some(MaterialKind::Lambertian(Lambertian{albedo: Color::new(0.2, 0.5, 0.5)}));
+    // let left_m = Some(MaterialKind::Metal(Metal{albedo: Color::new(0.799, 0.599, 0.799), fuzz: 0.0005}));
+    // let left_behind_m = Some(MaterialKind::Lambertian(Lambertian{albedo: Color::new(0.799, 0.599, 0.599)}));
+    // let right_m = Some(MaterialKind::Metal(Metal{albedo: Color::new(0.8, 0.6, 0.2), fuzz: 0.003}));
+    // // 折射率 1.33
+    // let left_dia_m = Some(MaterialKind::Dielectric(Dielectric{albedo: Color::new(0.8, 0.6, 0.2), refraction_index: 1.00 / 1.33}));
+    // let left_dia_small_m = Some(MaterialKind::Dielectric(Dielectric{albedo: Color::new(0.8, 0.6, 0.2), refraction_index: 1.00 / 2.5}));
 
-    world.put(Box::new(Sphere::new(Point::new(0.0,    0.0, -1.0), 0.5, center_m)));
-    world.put(Box::new(Sphere::new(Point::new(-1.0,    0.0, -1.0), 0.5, left_dia_m)));
-    world.put(Box::new(Sphere::new(Point::new(-1.0,    0.0, -1.0), 0.2, left_dia_small_m)));
-    // world.put(Box::new(Sphere::new(Point::new(-1.0,    0.0, -1.0), 0.5, left_m)));
-    world.put(Box::new(Sphere::new(Point::new(-3.5,    1.5, -5.5), 1.5, left_behind_m)));
-    world.put(Box::new(Sphere::new(Point::new(1.0,    0.0, -1.0), 0.5, right_m)));
+    // world.put(Box::new(Sphere::new(Point::new(0.0,    0.0, -1.0), 0.5, center_m)));
+    // world.put(Box::new(Sphere::new(Point::new(-1.0,    0.0, -1.0), 0.5, left_dia_m)));
+    // world.put(Box::new(Sphere::new(Point::new(-1.0,    0.0, -1.0), 0.2, left_dia_small_m)));
+    // // world.put(Box::new(Sphere::new(Point::new(-1.0,    0.0, -1.0), 0.5, left_m)));
+    // world.put(Box::new(Sphere::new(Point::new(-3.5,    1.5, -5.5), 1.5, left_behind_m)));
+    // world.put(Box::new(Sphere::new(Point::new(1.0,    0.0, -1.0), 0.5, right_m)));
     world.put(Box::new(Sphere::new(Point::new(0.0, -500.5, -1.0), 500.0, plane_m)));
 
+    // world.put(Box::new(Triangle::new(
+    //     Point::new(0.0, 0.5, 0.0),
+    //     Point::new(5.5, 0.5, 0.0),
+    //     Point::new(5.5, 5.5, 0.0),
+    //     Some(MaterialKind::Metal(Metal { albedo: Color::new(0.8, 0.6, 0.2), fuzz: 0.00001 }))
+    // )));
+    world.put(Box::new(Triangle::new(
+        Point::new(0.0, 0.5, 5.0),
+        Point::new(0.0, 5.5, -5.0),
+        Point::new(5.5, 0.5, 0.0),
+        Some(MaterialKind::Dielectric(Dielectric { albedo: Color::new(1.0, 1.0, 1.0), refraction_index: 1./1.5 }))
+    )));
+
+    gen_spheres(&mut world);
+
     camera.render(&world);
 }
+
+
+fn gen_spheres(world: &mut HittableList) {
+    let rng = &mut rng();
+
+    for _ in 0..500 {
+        let x = rng.random_range(-20..20);
+        let z = rng.random_range(-20..20);
+
+        let radius = rng.random_range(0.01..0.8);
+
+        // R = random(0.7, 0.95)  # 红通道
+        // G = random(R - 0.2, R + 0.2)  # 绿通道（与 R 相近）
+        // B = random(min(R, G) - 0.15, max(R, G) + 0.15)  # 蓝通道（与 R/G 相近）
+        // 基础值在 0.7~0.95 之间
+        let base:f32 = rng.random_range(0.7..0.95);
+        // 每个通道在 base 附近小幅波动（±0.15）
+        let r: f32 = rng.random_range((base - 0.15).max(0.6)..(base + 0.15).min(1.0));
+        let g: f32 = rng.random_range((base - 0.15).max(0.6)..(base + 0.15).min(1.0));
+        let b: f32 = rng.random_range((base - 0.15).max(0.6)..(base + 0.15).min(1.0));
+
+        let materail_color = Color::new(r,g, b);
+
+        let materail_kind =  rng.random_range(0.0..1.0);
+        let material = if materail_kind <= 0.33333 {
+            MaterialKind::Lambertian(Lambertian { albedo: materail_color })
+        } else if materail_kind > 0.3 && materail_kind <= 0.66666 {
+            MaterialKind::Metal(Metal { albedo: materail_color, fuzz: 0.00001 })
+        } else {
+            MaterialKind::Dielectric(Dielectric { albedo: materail_color, refraction_index: 1./1.5 })
+        };
+
+        world.put(Box::new(Sphere::new(Point::new(x as f32, 0., z as f32), radius, Some(material))));
+    }
+}

src/material.rs

@@ -31,7 +31,7 @@ impl Material for Lambertian {
 
         let mut scatter_direction = r_in.direction + Vec3::random_unit_on_hemisphere(hit_record.normal);
 
-        if (near_zero(scatter_direction)) {
+        if near_zero(scatter_direction) {
             scatter_direction = hit_record.normal;
         }
             
@@ -87,11 +87,6 @@ impl Material for Dielectric {
     fn scatter(&self, r_in: &Ray, hit_record: &mut HitRecord, attenuation: &mut Color, scattered: &mut Ray) -> bool {
 
         *attenuation = Color::new(1.0, 1.0, 1.0);
-        let ri = if hit_record.front_face {
-            1.0 / self.refraction_index
-        } else {
-            self.refraction_index
-        };
 
         let unit_direction = r_in.direction.normalize();
 

src/math_utils.rs

@@ -8,7 +8,7 @@ pub fn random_in_unit_disk() -> Vec3 {
     let rng = &mut rng();
     loop {
         let p = Vec3::new(rng.random_range(-1.0..1.0), rng.random_range(-1.0..1.0), 0.0);
-        if (p.length_squared() < 1.0) {
+        if p.length_squared() < 1.0 {
             return p;
         }
     } 

src/triangle.rs

@@ -0,0 +1,100 @@
+use crate::{hittable::Hittable, material::MaterialKind, math_utils::is_front_face, types_defined::{HitRecord, Point, Ray, Vec3}};
+
+pub struct Triangle {
+    pub points: Vec<Vec3>,
+    pub material: Option<MaterialKind>,
+}
+
+impl Triangle {
+    pub fn new(p1: Point, p2: Point, p3: Point, material: Option<MaterialKind>,) -> Self {
+        Triangle { 
+            points: vec![
+                p1, p2, p3
+            ],
+            material: material
+        }
+    }
+}
+
+impl Hittable for Triangle {
+
+    fn hit(&self, r: &Ray, t_min: f32, t_max: f32, hit_record: &mut HitRecord) -> bool {
+        let p0 = self.points[0];
+        let p1 = self.points[1];
+        let p2 = self.points[2];
+        let u = Vec3 {
+            x: p1.x - p0.x,
+            y: p1.y - p0.y,
+            z: p1.z - p0.z,
+        };
+        let v = Vec3 {
+            x: p2.x - p0.x,
+            y: p2.y - p0.y,
+            z: p2.z - p0.z,
+        };
+        let normal = Vec3 {
+            x: u.y * v.z - u.z * v.y,
+            y: u.z * v.x - u.x * v.z,
+            z: u.x * v.y - u.y * v.x,
+        };
+        let denominator = r.direction.x * normal.x + r.direction.y * normal.y + r.direction.z * normal.z;
+        if denominator.abs() < std::f32::EPSILON {
+            return false;
+        }
+        let w0 = Vec3 {
+            x: r.point.x - p0.x,
+            y: r.point.y - p0.y,
+            z: r.point.z - p0.z,
+        };
+        let t = -(w0.x * normal.x + w0.y * normal.y + w0.z * normal.z) / denominator;
+        if t < t_min || t > t_max {
+            return false;
+        }
+        let P = Vec3 {
+            x: r.point.x + t * r.direction.x,
+            y: r.point.y + t * r.direction.y,
+            z: r.point.z + t * r.direction.z,
+        };
+        let w = Vec3 {
+            x: P.x - p0.x,
+            y: P.y - p0.y,
+            z: P.z - p0.z,
+        };
+        let uv_cross = Vec3 {
+            x: u.y * v.z - u.z * v.y,
+            y: u.z * v.x - u.x * v.z,
+            z: u.x * v.y - u.y * v.x,
+        };
+        let wv_cross = Vec3 {
+            x: w.y * v.z - w.z * v.y,
+            y: w.z * v.x - w.x * v.z,
+            z: w.x * v.y - w.y * v.x,
+        };
+        let uw_cross = Vec3 {
+            x: u.y * w.z - u.z * w.y,
+            y: u.z * w.x - u.x * w.z,
+            z: u.x * w.y - u.y * w.x,
+        };
+        let alpha = (wv_cross.x * normal.x + wv_cross.y * normal.y + wv_cross.z * normal.z) / (uv_cross.x * normal.x + uv_cross.y * normal.y + uv_cross.z * normal.z);
+        let beta = (uw_cross.x * normal.x + uw_cross.y * normal.y + uw_cross.z * normal.z) / (uv_cross.x * normal.x + uv_cross.y * normal.y + uv_cross.z * normal.z);
+        if alpha >= 0.0 && beta >= 0.0 && alpha + beta <= 1.0 {
+        
+            hit_record.p = P;
+            hit_record.t = t;
+            hit_record.normal = normal;
+            hit_record.front_face = is_front_face(r, normal);
+            hit_record.material = if let Some(ref m) = self.material {
+                match m {
+                    MaterialKind::Lambertian(l) => Some(MaterialKind::Lambertian(l.clone())),
+                    MaterialKind::Metal(m) => Some(MaterialKind::Metal(m.clone())),
+                    MaterialKind::Dielectric(d) => Some(MaterialKind::Dielectric(d.clone())),
+                }
+            } else {
+                None
+            };
+
+            return true;
+        }
+        false
+    }
+}

src/types_defined.rs

@@ -1,5 +1,5 @@
 use std::{fs::File, io::{BufWriter}};
-use crate::{material::MaterialKind, vec3};
+use crate::{material::MaterialKind};
 use crate::ppm_writer::PPMWriter;
 
 /*
@@ -38,8 +38,8 @@ pub struct Camera<'a> {
     // pub viewport_width: f32,
     // pub viewport_height: f32,
     pub center: Point,
-    pub look_at: Point,
-    pub v_up: Vec3,
+    // pub look_at: Point,
+    // pub v_up: Vec3,
     // pub focal_length: Vec3,
     // pub viewport_u: Vec3,
     // pub viewport_v: Vec3,

src/vec3.rs

@@ -1,7 +1,7 @@
 
-use std::{fmt::Display, ops::{Add, AddAssign, Div, Mul, MulAssign, Sub}};
+use std::{fmt::Display, iter::Sum, ops::{Add, AddAssign, Div, Mul, MulAssign, Sub}};
 use std::fmt;
-use rand::{thread_rng, Rng};
+use rand::{rng, Rng};
 use crate::types_defined::Vec3;
 
 impl Display for Vec3 {
@@ -50,13 +50,13 @@ impl Vec3 {
     }
 
     pub fn random_range(min: f32, max: f32) -> Self {
-        let rng = &mut thread_rng();
-        Vec3::new(rng.gen_range(min..max), rng.gen_range(min..max), rng.gen_range(min..max))
+        let rng = &mut rng();
+        Vec3::new(rng.random_range(min..max), rng.random_range(min..max), rng.random_range(min..max))
     }
 
     pub fn random() -> Self {
-        let rng = &mut thread_rng();
-        Vec3::new(rng.r#gen(), rng.r#gen(), rng.r#gen())
+        let rng = &mut rng();
+        Vec3::new(rng.random(), rng.random(), rng.random())
     }
 
     pub fn random_unit() -> Self {
@@ -159,3 +159,17 @@ impl MulAssign<f32> for Vec3 {
         *self = *self * scalar;
     }
 }
+
+impl Sum for Vec3 {
+    fn sum<I: Iterator<Item = Self>>(iter: I) -> Self {
+        let mut sum_x = 0.0;
+        let mut sum_y = 0.0;
+        let mut sum_z = 0.0;
+        for vec in iter {
+            sum_x += vec.x;
+            sum_y += vec.y;
+            sum_z += vec.z;
+        }
+        Vec3 { x: sum_x, y: sum_y, z: sum_z }
+    }
+}