Starting builder pattern for Camera

I'm going to change the Camera construction to use the builder pattern.
This means I need to implement trait Default for Camera, and then a
bunch of functions for setting the properties.

.gitignore

@@ -1 +0,0 @@
-/target

Cargo.toml

@@ -1,10 +1,19 @@
 [package]
 name = "rustpt"
 version = "0.1.0"
-edition = "2024"
+edition = "2021"
 
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
+[[bin]]
+name = "rustpt_cli"
+path = "src/cli_tool.rs"
+
+[[bin]]
+name = "rustpt_gui"
+path = "src/gui_tool.rs"
+
 [dependencies]
-rand = { version = "0.9", features = ["small_rng"] }
-itertools = { version = "0.14" }
+rand = { version = "0.8.5", features = ["small_rng"] }
+itertools = { version = "0.11.0" }
+eframe = "0.25.0"

src/cli_tool.rs

@@ -1,26 +1,33 @@
-mod primitives;
-mod renderer;
-mod scene;
+#![warn(clippy::all, rust_2018_idioms, rust_2018_compatibility)]
+use rustpt::primitives::{
+    Vec2i,
+    Vec3,
+};
+use rustpt::scene::{
+    Camera,
+    Scene
+};
 
-use crate::primitives::{Vec2i, Vec3};
-use crate::scene::{Camera, Scene};
-
-use crate::renderer::{RenderProperties, Tile};
+use rustpt::renderer::{
+    Tile,
+    RenderProperties,
+};
 
 use rand::SeedableRng;
 use rand::rngs::SmallRng;
 
+
 fn main() {
     // image
     let aspect_ratio = 3.0 / 2.0;
     let image = Vec2i {
         x: 400,
-        y: (400.0 / aspect_ratio) as i32,
+        y: (400.0 / aspect_ratio) as i32
     };
 
     let render_config = RenderProperties {
         samples: 10,
-        bounces: 50,
+        bounces: 50
     };
 
     // random generator
@@ -37,7 +44,7 @@ fn main() {
             0.1, // aperture
             10.0, // dist_to_focus
         ),
-        world: Scene::random_world(&mut small_rng),
+        world: Scene::random_world(&mut small_rng)
     };
     
     // render

src/gui_tool.rs

@@ -0,0 +1,36 @@
+#![warn(clippy::all, rust_2018_idioms)]
+use eframe::{egui, Frame};
+
+fn main() -> Result<(), eframe::Error> {
+    let options = eframe::NativeOptions {
+        viewport: egui::ViewportBuilder::default()
+            .with_inner_size([800.0, 600.0])
+            .with_min_inner_size([50.0, 50.0])
+            .with_title("RustPT GUI Tool"),
+            ..Default::default()
+    };
+    eframe::run_native(
+        "app name?",
+        options,
+    Box::new(
+        | cc | Box::new(RtApp::new(cc))
+    ))
+}
+
+#[derive(Default)]
+struct RtApp;
+
+impl RtApp {
+    fn new(cc: &eframe::CreationContext<'_>) -> Self {
+        Self::default()
+    }
+}
+
+impl eframe::App for RtApp {
+    fn update(&mut self, ctx: &egui::Context, frame: &mut Frame) {
+        egui::SidePanel::left("Render Properties").show(ctx, |ui| {
+            ui.heading("Render Properties");
+            ui.label("")
+        });
+    }
+}

src/lib.rs

@@ -0,0 +1,4 @@
+#![warn(clippy::all, rust_2018_idioms, rust_2018_compatibility)]
+pub mod primitives;
+pub mod scene;
+pub mod renderer;

src/primitives.rs

@@ -1,10 +1,21 @@
+
+use std::ops::{
+    Add,
+    AddAssign,
+    Sub,
+    SubAssign,
+    Mul,
+    MulAssign,
+    Div,
+    DivAssign,
+    Neg,
+};
 use std::fmt;
 use std::fmt::Display;
-use std::ops::{Add, AddAssign, Div, DivAssign, Mul, MulAssign, Neg, Sub, SubAssign};
 
 use rand::Rng;
-use rand::distr::Uniform;
 use rand::rngs::SmallRng;
+use rand::distributions::Uniform;
 
 pub type Vec2i = Vec2<i32>;
 pub type Vec2f = Vec2<f32>;
@@ -15,6 +26,7 @@ pub struct Vec2<T> {
     pub y: T,
 }
 
+
 impl Vec2<f32> {
     pub fn zero() -> Vec2<f32> {
         Vec2{ x: 0.0, y: 0.0 }
@@ -25,44 +37,33 @@ impl Vec2<f32> {
     }
 
     pub fn rand(srng: &mut SmallRng, distrib: Uniform<f32>) -> Vec2<f32> {
-        Vec2 {
-            x: srng.sample(distrib),
-            y: srng.sample(distrib),
-        }
+        Vec2 { x: srng.sample(distrib), y: srng.sample(distrib) }
     }
+
 }
 
 impl <T> Vec2<T> 
-where
-    T: std::ops::Mul,
-{
+where T: std::ops::Mul{
     pub fn new(x: T, y: T) -> Vec2<T> {
         Vec2{x, y}
     }
 }
 
 impl <T> Add for Vec2 <T>
-where
-    T: std::ops::Add<Output = T>,
-{
+where T: std::ops::Add<Output = T>{
     type Output = Vec2<T>;
     fn add(self, other: Vec2<T>) -> Vec2<T> {
-        Vec2 {
-            x: self.x + other.x,
-            y: self.y + other.y,
-        }
+        Vec2 { x: self.x + other.x, y: self.y + other.y }
     }
 }
 
 impl <T> Mul for Vec2<T> 
-where
-    T: std::ops::Mul<Output = T>,
-{
+where T: std::ops::Mul<Output = T>{
     type Output = Vec2<T>;
     fn mul(self, other: Vec2<T>) -> Vec2<T> {
         Vec2 {
             x: self.x * other.x,
-            y: self.y * other.y,
+            y: self.y * other.y
         }
     }
 }
@@ -72,7 +73,7 @@ impl Div<f32> for Vec2<f32> {
     fn div(self, other: f32) -> Vec2<f32> {
         Vec2 {
             x: 1.0/other * self.x,
-            y: 1.0 / other * self.y,
+            y: 1.0/other * self.y
         }
     }
 }
@@ -82,30 +83,25 @@ impl Div<i32> for Vec2<i32> {
     fn div(self, other: i32) -> Vec2<i32> {
         Vec2 {
             x: self.x / other,
-            y: self.y / other,
+            y: self.y / other
         }
     }
 }
 
 impl <T> Div<Vec2<T>> for Vec2<T> 
-where
-    T: std::ops::Div<Output = T>,
-{
+where T: std::ops::Div<Output = T>{
     type Output = Vec2<T>;
     fn div(self, other: Vec2<T>) -> Vec2<T> {
         Vec2 {
             x: self.x / other.x,
-            y: self.y / other.y,
+            y: self.y / other.y
         }
     }
 }
 
 impl <T> Display for Vec2<T> 
-where
-    T: Display,
-{
-    // nested type still needs to have Display
-    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
+where T: Display { // nested type still needs to have Display
+    fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
         let str = format!("{} {}", self.x, self.y);
         fmt.write_str(&str)
     }
@@ -135,7 +131,7 @@ impl Vec3 {
         Vec3 {
             x: 1.0,
             y: 1.0,
-            z: 1.0,
+            z: 1.0
         }
     }
 
@@ -148,14 +144,11 @@ impl Vec3 {
     }
 
     pub fn rand_in_unit_sphere(srng: &mut SmallRng) -> Vec3 {
-        let distrib = Uniform::new(-1.0, 1.0).unwrap();
+        let distrib = Uniform::new(-1.0, 1.0);
         loop {
             let p = Vec3::rand(srng, distrib);
-            if p.length_squared() >= 1.0 {
-                continue;
-            } else {
-                return p;
-            }
+            if p.length_squared() >= 1.0 { continue; }
+            else { return p; }
         }
     }
 
@@ -163,20 +156,17 @@ impl Vec3 {
         let distrib = Uniform::new(-1.0, 1.0);
         loop {
             let p = Vec3 {
-                x: srng.sample(distrib.unwrap()),
-                y: srng.sample(distrib.unwrap()),
+                x: srng.sample(distrib),
+                y: srng.sample(distrib),
                 z: 0.0,
             };
-            if p.length_squared() >= 1.0 {
-                continue;
-            } else {
-                return p;
-            }
+            if p.length_squared() >= 1.0 { continue; }
+            else { return p; }
         }
     }
 
     pub fn rand_unit_vector(srng: &mut SmallRng) -> Vec3 {
-        Vec3::as_unit(Vec3::rand_in_unit_sphere(srng))
+        return Vec3::as_unit(Vec3::rand_in_unit_sphere(srng));
     }
 
 	pub fn length(&self) -> f32 {
@@ -189,6 +179,7 @@ impl Vec3 {
     
     // roughly equivalent to the `void write_color(...)` in the book
     pub fn print_ppm(&self, samples_per_pixel: u32) -> String {
+
         let scale = 1.0 / samples_per_pixel as f32;
         
         // now with gamma correction
@@ -204,11 +195,14 @@ impl Vec3 {
     
     pub fn near_zero(&self) -> bool {
         let epsilon: f32 = 1e-4;
-        self.x.abs() < epsilon && self.y.abs() < epsilon && self.z.abs() < epsilon
+        return 
+            self.x.abs() < epsilon &&
+            self.y.abs() < epsilon &&
+            self.z.abs() < epsilon
     }
     
     pub fn reflect(v: Vec3, n: Vec3) -> Vec3 {
-        v - n * Vec3::dot(v, n) * 2.0
+        return v - n * Vec3::dot(v, n) * 2.0;
     }
     
     pub fn refract(uv: Vec3, n: Vec3, etai_over_etat: f32) -> Vec3 {
@@ -219,14 +213,16 @@ impl Vec3 {
     }
 
     pub fn dot(left: Vec3, right: Vec3) -> f32{
-        left.x * right.x + left.y * right.y + left.z * right.z
+        left.x * right.x +
+        left.y * right.y +
+        left.z * right.z
     }
     
     pub fn cross(u: Vec3, v: Vec3) -> Vec3{
         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,
+            z: u.x * v.y - u.y * v.x
         }
     }
     
@@ -234,6 +230,7 @@ impl Vec3 {
         let len = v.length();
         v / len
     }
+
 }
 impl Add for Vec3 {
 	type Output = Vec3;
@@ -251,7 +248,7 @@ impl AddAssign for Vec3 {
 		*self = Self {
 			x: self.x + other.x,
 			y: self.y + other.y,
-            z: self.z + other.z,
+			z: self.z + other.z
 		};
 	}
 }
@@ -272,7 +269,7 @@ impl SubAssign for Vec3 {
 		*self = Self {
 			x: self.x - other.x,
 			y: self.y - other.y,
-            z: self.z - other.z,
+			z: self.z - other.z
 		};
 	}
 }
@@ -304,7 +301,7 @@ impl MulAssign<Vec3> for Vec3 {
 		*self = Self {
 			x: self.x * other.x,
 			y: self.y * other.y,
-            z: self.z * other.z,
+			z: self.z * other.z
 		};
 	}
 }
@@ -314,7 +311,7 @@ impl MulAssign<f32> for Vec3 {
 		*self = Self {
 			x: self.x * other,
 			y: self.y * other,
-            z: self.z * other,
+			z: self.z * other
 		};
 	}   
 }
@@ -346,7 +343,7 @@ impl DivAssign<Vec3> for Vec3 {
 		*self = Self {
 			x: self.x / other.x,
 			y: self.y / other.y,
-            z: self.z / other.z,
+			z: self.z / other.z
 		};
 	}
 }
@@ -356,7 +353,7 @@ impl DivAssign<f32> for Vec3 {
 		*self = Self {
 			x: self.x / other,
 			y: self.y / other,
-            z: self.z / other,
+			z: self.z / other
 		};
 	}
 }
@@ -373,10 +370,11 @@ impl Neg for Vec3 {
 }
 
 impl Display for Vec3 {
-    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
+	fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
 		let str = format!("{} {} {}", self.x, self.y, self.z);
 		fmt.write_str(&str)?;
 		Ok(())
+		
 	}
 }
 
@@ -660,6 +658,7 @@ mod test {
         let refl = Vec3::reflect(ray, normal);
         let expected = Vec3::new(-1.0, 0.0, 0.0);
         assert!(refl == expected);
+
     }
 
     #[test]
@@ -667,6 +666,7 @@ mod test {
         let ray = Vec3::new(1.0, 0.0, 0.0);
         let normal = Vec3::as_unit(Vec3::new(-1.0, 1.0, 0.0));
 
+        
         let refl = Vec3::reflect(ray, normal);
         let expected = Vec3::new(0.0, 1.0, 0.0);
         let diff = refl - expected;
@@ -678,9 +678,12 @@ mod test {
     fn check_lerp(){
         let ray = Ray{
             orig: Vec3::new(0.0, 0.0, 0.0),
-            dir: Vec3::new(1.0, 1.0, 0.0),
+            dir: Vec3::new(1.0, 1.0, 0.0)
         };
         let half = ray.at(0.5);
-        assert_eq!(half, Vec3::new(0.5, 0.5, 0.0));
+        assert_eq!(
+            half,
+            Vec3::new(0.5, 0.5, 0.0)
+        );
     }
 }

src/renderer.rs

@@ -1,15 +1,21 @@
-use crate::primitives::{Ray, Rect, Vec2f, Vec2i, Vec3};
-use crate::scene::{Hittable, Scene};
+
+use crate::primitives::{
+    Vec2i,
+    Vec2f,
+    Vec3,
+    Ray,
+    Rect,
+};
+use crate::scene::{
+    Hittable,
+    Scene,
+};
 
 use rand::rngs::SmallRng;
 
 use itertools::{self, Itertools};
 
-const SKY_COLOR: Vec3 = Vec3 {
-    x: 0.5,
-    y: 0.7,
-    z: 1.0,
-};
+const SKY_COLOR: Vec3 = Vec3 { x: 0.5, y: 0.7, z: 1.0};
 
 pub struct RenderProperties {
     pub samples: u32, // samples are averaged results over a pixel
@@ -22,7 +28,10 @@ fn to_uv(coord: Vec2i, img_size: Vec2i) -> Vec2f {
     Vec2f::new(u, v)
 }
 
-fn ray_color(r: Ray, surface: &Hittable, depth: u32, rng: &mut SmallRng) -> Vec3 {
+fn ray_color(
+    r: Ray, surface: &Hittable, depth: u32,
+    rng: &mut SmallRng,
+) -> Vec3 {
     // recursion guard
     if depth == 0 {
         return Vec3::zero();
@@ -35,22 +44,26 @@ fn ray_color(r: Ray, surface: &Hittable, depth: u32, rng: &mut SmallRng) -> Vec3
             dir: Vec3::zero(),
         };
         let mut attenuation = Vec3::zero();
-        if record
-            .material
-            .scatter(r, &record, &mut attenuation, &mut scattered, rng)
-        {
-            return attenuation * ray_color(scattered, surface, depth - 1, rng);
+        if record.material.scatter(
+            r,
+            &record,
+            &mut attenuation,
+            &mut scattered,
+            rng
+        ) {
+            return attenuation * ray_color(
+                scattered, surface, depth-1, rng
+            );
         }
     } // TODO: explicit else block
     // Rust gets angry about the inner if{} block because it evaluates to ()
     // when the else path is taken. This is a problem for a function
     // that returns Vec3 and not ().
 
-    {
-        // when nothing is struck, return sky color
+    { // when nothing is struck, return sky color
         let unitdir = Vec3::as_unit(r.dir);
         let t = 0.5 * (unitdir.y + 1.0);
-        Vec3::ones() * (1.0 - t) + SKY_COLOR * t
+        return Vec3::ones() * (1.0 - t) + SKY_COLOR * t
     }
 }
 
@@ -62,14 +75,18 @@ fn sample_pixel(
     // Supplied by the execution environment (the thread)
     rng: &mut SmallRng,
 ) -> Vec3{
-    (0..render_props.samples).fold(Vec3::zero(), |color, _sample| -> Vec3 {
+    (0..render_props.samples)
+    .fold(
+        Vec3::zero(),
+        |color, _sample| -> Vec3 {
             let uv = to_uv(coord, img_size);
             let ray = scene.camera.get_ray(uv.x, uv.y, rng);
             if ray.dir.x.is_nan() {
                 panic!("Ray dir.x is NAN");
             }
             color + ray_color(ray, &scene.world, render_props.bounces, rng)
-    })
+        }
+    )
 }
 
 pub struct Tile {
@@ -85,25 +102,22 @@ impl Tile {
         properties: &RenderProperties, // TODO: Place image size in render properties?
         rng: &mut SmallRng,
     ) -> Self {
-        let pixel_iter =
-            (bounds.y..(bounds.y + bounds.h)).cartesian_product(bounds.x..(bounds.x + bounds.w));
-        let pixels = pixel_iter
-            .map(|coord| -> Vec3 {
+        let pixel_iter = (bounds.y..(bounds.y + bounds.h))
+            .cartesian_product( bounds.x..(bounds.x + bounds.w));
+        let pixels = pixel_iter.map(
+            |coord| -> Vec3 {
                 sample_pixel(
-                    Vec2i {
-                        x: coord.1,
-                        y: coord.0,
-                    },
+                    Vec2i{x: coord.1, y: coord.0},
                     scene,
                     properties,
                     img_size,
                     rng,
                 )
-            })
-            .collect();
+            }
+        ).collect();
         Self {
             _bounds: bounds,
-            pixels,
+            pixels
         }
     }
     pub fn render_line(
@@ -114,16 +128,11 @@ impl Tile {
         rng: &mut SmallRng, // rng utils
     ) -> Self {
         Tile::render_tile(
-            Rect {
-                x: 0,
-                y,
-                w: img_size.x,
-                h: 1,
-            },
+            Rect{ x: 0, y, w: img_size.x, h: 1 },
             img_size,
             scene,
             properties,
-            rng,
+            rng
         )
     }
 }

src/scene.rs

@@ -1,8 +1,9 @@
-use crate::primitives::{Ray, Vec3};
+
+use crate::primitives::{Vec3, Ray};
 
 use rand::Rng;
-use rand::distr::Uniform;
 use rand::rngs::SmallRng;
+use rand::distributions::Uniform;
 
 pub struct HitRecord{
     pub p: Vec3,
@@ -13,47 +14,34 @@ pub struct HitRecord {
 }
 
 impl HitRecord{
-    pub fn set_face_normal(&mut self, r: Ray, outward_normal: Vec3) {
+    pub fn set_face_normal(&mut self, r: Ray, outward_normal: Vec3) -> (){
         self.front_face = Vec3::dot(r.dir, outward_normal) < 0.0;
-        self.normal = if self.front_face {
-            outward_normal
-        } else {
-            -outward_normal
-        };
+        self.normal = if self.front_face { outward_normal } else { -outward_normal };
     }
 }
 
 #[derive (Clone)]
 pub enum Hittable {
-    Sphere {
-        center: Vec3,
-        radius: f32,
-        material: Material,
-    },
-    HittableList {
-        hittables: Vec<Hittable>,
-    },
+    Sphere { center: Vec3, radius: f32, material: Material },
+    HittableList { hittables: Vec<Hittable> }
 }
 
 impl Hittable {
     pub fn hit(&self, r: Ray, t_min: f32, t_max: f32) -> Option<HitRecord> {
         match self {
-            Hittable::HittableList { hittables } => hittables
-                .iter()
-                .map(|obj| -> Option<HitRecord> { obj.hit(r, t_min, t_max) })
-                .filter(|obj| obj.is_some())
+            Hittable::HittableList { hittables } => {
+                hittables.iter()
+                .map( |obj| -> Option<HitRecord> {
+                    obj.hit(r, t_min, t_max)
+                }).filter(|obj| obj.is_some())
                 .min_by(|lhs, rhs| {
                     let lhs = lhs.as_ref().unwrap();
                     let rhs = rhs.as_ref().unwrap();
                     lhs.t.partial_cmp(&rhs.t).expect("Couldn't compare??")
-                })
-                .unwrap_or(None),
+                }).unwrap_or(None)
+            }
 
-            Hittable::Sphere {
-                center,
-                radius,
-                material,
-            } => {
+            Hittable::Sphere { center, radius, material } => {
                 let oc = r.orig - *center;
                 let a = r.dir.length_squared();
                 let half_b = Vec3::dot(oc, r.dir);
@@ -93,6 +81,7 @@ impl Hittable {
     }
 }
 
+
 #[derive(Copy, Clone, Debug)]
 pub enum Material{
     Lambertian { albedo: Vec3 },
@@ -114,8 +103,7 @@ impl Material {
                 let scatter_dir = rec.normal + Vec3::rand_unit_vector(srng);
                 // The compiler might be smart enough to compute this ^^^ just once. In which case,
                 // I don't need to do this weird dance. Oh well. It'll work.
-                let scatter_dir = if scatter_dir.near_zero() {
-                    // if near zero,
+                let scatter_dir = if scatter_dir.near_zero() {  // if near zero,
                     rec.normal                                  // replace with normal
                 } else {
                     scatter_dir                                 // else preserve current
@@ -126,48 +114,44 @@ impl Material {
                 // using them at all)
                 *scattered = Ray{
                     orig: rec.p,
-                    dir: scatter_dir,
+                    dir: scatter_dir
                 };
                 *attenuation = *albedo; // deref on both sides? Wacky
-                true
-            }
+                return true;
+            },
             Material::Metal { albedo, fuzz } => {
-                let reflected = Vec3::reflect(Vec3::as_unit(ray_in.dir), rec.normal);
+                let reflected = Vec3::reflect(
+                    Vec3::as_unit(ray_in.dir),
+                    rec.normal
+                );
                 *scattered = Ray{
                     orig: rec.p,
                     dir: reflected + Vec3::rand_in_unit_sphere(srng) * *fuzz,
                 };
                 *attenuation = *albedo;
-                Vec3::dot(scattered.dir, rec.normal) > 0.0
-            }
+                return Vec3::dot(scattered.dir, rec.normal) > 0.0;
+            },
             Material::Dielectric { index_refraction } => {
                 *attenuation = Vec3::ones();
-                let refraction_ratio = if rec.front_face {
-                    1.0 / index_refraction
-                } else {
-                    *index_refraction
-                };
+                let refraction_ratio = if rec.front_face { 1.0 / index_refraction } else { *index_refraction };
                 
                 let unit_direction = Vec3::as_unit(ray_in.dir);
                 let cos_theta = Vec3::dot(-unit_direction, rec.normal).min(1.0);
                 let sin_theta = (1.0 - cos_theta * cos_theta).sqrt();
 
                 let cannot_refract = refraction_ratio * sin_theta > 1.0;
-                let distrib_zero_one = Uniform::new(0.0, 1.0).unwrap();
-                let direction = if cannot_refract
-                    || Material::reflectance(cos_theta, refraction_ratio)
-                        > srng.sample(distrib_zero_one)
-                {
+                let distrib_zero_one = Uniform::new(0.0, 1.0);
+                let direction = if cannot_refract || Material::reflectance(cos_theta, refraction_ratio) > srng.sample(distrib_zero_one) {
                     Vec3::reflect(unit_direction, rec.normal)
                 } else {
                     Vec3::refract(unit_direction, rec.normal, refraction_ratio)
                 };
                 *scattered = Ray {
                     orig: rec.p,
-                    dir: direction,
+                    dir: direction 
                 };
-                true
-            }
+                return true;
+            },
         }
     }
 
@@ -175,7 +159,7 @@ impl Material {
         // Schlick's approximation for reflectance.
         let r0 = (1.0 - ref_idx) / (1.0 + ref_idx);
         let r0 = r0 * r0;
-        r0 + (1.0 - r0) * (1.0 - cosine).powf(5.0)
+        return r0 + (1.0 - r0) * (1.0 - cosine).powf(5.0);
     }
 }
 
@@ -190,21 +174,42 @@ pub struct Camera {
     lower_left_corner: Vec3,
     horizontal: Vec3,
     vertical: Vec3,
-    u: Vec3,
-    v: Vec3, /*w: Vec3,*/
+    u: Vec3, v: Vec3, /*w: Vec3,*/
     lens_radius: f32,
 }
 
 impl Camera {
-    pub fn new(
-        lookfrom: Vec3,
-        lookat: Vec3,
-        vup: Vec3,
-        vfov: f32,
-        aspect_ratio: f32,
-        aperture: f32,
-        focus_dist: f32,
-    ) -> Camera {
+    pub fn new() -> Camera {
+        Self::default()
+    }
+
+    pub fn get_ray(&self, s: f32, t: f32, srng: &mut SmallRng) -> Ray {
+        let rd = Vec3::rand_in_unit_disk(srng) * self.lens_radius;
+        let offset = self.u * rd.x + self.v * rd.y;
+
+        let dir = self.lower_left_corner
+                + self.horizontal * s
+                + self.vertical * t 
+                - self.origin - offset;
+        Ray{
+            orig: self.origin + offset,
+            dir,
+        }
+    }
+}
+
+impl Default for Camera {
+    fn default() -> Self {
+        // defaults are the same as the hard-coded properties passed from main
+        // ... except for the `lookfrom` position: (13.0, 2.0, 3.0) became (10.0, 0..)
+        let lookfrom = Vec3::new(10.0, 0.0, 0.0);
+        let lookat = Vec3 { x: 1.0, y: 0.0, z: 0.0 };
+        let vup = Vec3::new(0.0, 1.0, 0.0);
+        let vfov = 20.0;
+        let aspect_ratio = 3.0 / 2.0;
+        let aperture = 0.1;
+        let focus_dist = 10.0;
+
         let theta = degrees_to_radians(vfov);
         let h = (theta / 2.0).tan();
         let vp_height = 2.0 * h;
@@ -224,24 +229,12 @@ impl Camera {
             lower_left_corner,
             horizontal: horiz,
             vertical: verti,
-            u,
-            v, /* w,*/
+            u, v, /* w,*/
             lens_radius: aperture / 2.0,
         }
     }
+}
 
-    pub fn get_ray(&self, s: f32, t: f32, srng: &mut SmallRng) -> Ray {
-        let rd = Vec3::rand_in_unit_disk(srng) * self.lens_radius;
-        let offset = self.u * rd.x + self.v * rd.y;
-
-        let dir =
-            self.lower_left_corner + self.horizontal * s + self.vertical * t - self.origin - offset;
-        Ray {
-            orig: self.origin + offset,
-            dir,
-        }
-    }
-}
 
 pub struct Scene {
     pub camera: Camera,
@@ -250,20 +243,12 @@ pub struct Scene {
 
 impl Scene {
     pub fn random_world(srng: &mut SmallRng) -> Hittable {
-        let mat_ground = Material::Lambertian {
-            albedo: Vec3::new(0.5, 0.5, 0.5),
-        };
-        let mut world = Hittable::HittableList {
-            hittables: Vec::<Hittable>::new(),
-        };
+        let mat_ground = Material::Lambertian { albedo: Vec3::new(0.5, 0.5, 0.5) };
+        let mut world = Hittable::HittableList { hittables : Vec::<Hittable>::new() };
         
-        world.push(Hittable::Sphere {
-            center: Vec3::new(0.0, -1000.0, 0.0),
-            radius: 1000.0,
-            material: mat_ground,
-        });
+        world.push( Hittable::Sphere { center: Vec3::new(0.0, -1000.0, 0.0), radius: 1000.0, material: mat_ground });
         
-        let distrib_zero_one = Uniform::new(0.0, 1.0).unwrap();
+        let distrib_zero_one = Uniform::new(0.0, 1.0);
         for a in -11..11 {
             for b in -11..11 {
                 let choose_mat = srng.sample(distrib_zero_one);
@@ -273,70 +258,68 @@ impl Scene {
                     z: b as f32 + 0.9 * srng.sample(distrib_zero_one),
                 };
                 if (center - Vec3::new(4.0, 0.2, 0.0)).length() > 0.9 {
+
                     if choose_mat < 0.8 {
                         // diffuse
-                        let albedo =
-                            Vec3::rand(srng, distrib_zero_one) * Vec3::rand(srng, distrib_zero_one);
+                        let albedo = Vec3::rand(srng, distrib_zero_one) * Vec3::rand(srng, distrib_zero_one);
                         let sphere_material = Material::Lambertian { albedo };
-                        world.push(Hittable::Sphere {
+                        world.push(
+                            Hittable::Sphere {
                                 center,
                                 radius: 0.2,
                                 material: sphere_material,
-                        });
+                            }
+                        );
                     } else if choose_mat < 0.95 {
                         // metal
-                        let distr_albedo = Uniform::new(0.5, 1.0).unwrap();
-                        let distr_fuzz = Uniform::new(0.0, 0.5).unwrap();
+                        let distr_albedo = Uniform::new(0.5, 1.0);
+                        let distr_fuzz = Uniform::new(0.0, 0.5);
 
                         let albedo = Vec3::rand(srng, distr_albedo);
                         let fuzz = srng.sample(distr_fuzz);
                         let material = Material::Metal { albedo, fuzz };
-                        world.push(Hittable::Sphere {
+                        world.push(
+                            Hittable::Sphere {
                                 center,
                                 radius: 0.2,
-                            material,
-                        });
+                                material: material,
+                            }
+                        );
                     } else {
                         // glass
-                        let material = Material::Dielectric {
-                            index_refraction: 1.5,
-                        };
-                        world.push(Hittable::Sphere {
+                        let material = Material::Dielectric { index_refraction: 1.5 };
+                        world.push(
+                            Hittable::Sphere{
                                 center,
                                 radius: 0.2,
-                            material,
-                        });
+                                material: material,
+                            }
+                        );
+
                     };
                 }
             }
         }
 
-        let material1 = Material::Dielectric {
-            index_refraction: 1.5,
-        };
+        let material1 = Material::Dielectric { index_refraction: 1.5 };
         world.push( Hittable::Sphere{
             center: Vec3::new(0.0, 1.0, 0.0),
             radius: 1.0,
-            material: material1,
+            material: material1
         });
 
-        let material2 = Material::Lambertian {
-            albedo: Vec3::new(0.4, 0.2, 0.1),
-        };
+        let material2 = Material::Lambertian { albedo: Vec3::new(0.4, 0.2, 0.1) };
         world.push( Hittable::Sphere {
             center: Vec3::new(-4.0, 1.0, 0.0),
             radius: 1.0,
-            material: material2,
+            material: material2
         });
 
-        let material3 = Material::Metal {
-            albedo: Vec3::new(0.7, 0.6, 0.5),
-            fuzz: 0.0,
-        };
+        let material3 = Material::Metal { albedo: Vec3::new(0.7, 0.6, 0.5), fuzz: 0.0 };
         world.push( Hittable::Sphere {
             center: Vec3::new(4.0, 1.0, 0.0),
             radius: 1.0,
-            material: material3,
+            material: material3
         });
         world
     }