Add Default implementation for Scene.

This makes it so adding new fields doesn't require changing all the
Scene's at once.

rtiow/src/renderer.rs

@@ -1,6 +1,4 @@
 use std::fmt;
-use std::io;
-use std::io::Write;
 use std::path::Path;
 use std::path::PathBuf;
 use std::str;
@@ -24,8 +22,11 @@ use rand::Rng;
 use crate::camera::Camera;
 use crate::hitable::Hit;
 use crate::human;
+use crate::material::Lambertian;
 use crate::ray::Ray;
 use crate::scenes;
+use crate::sphere::Sphere;
+use crate::texture::ConstantTexture;
 use crate::texture::EnvMap;
 use crate::vec3::Vec3;
 
@@ -186,6 +187,42 @@ pub struct Scene {
     pub env_map: Option<EnvMap>,
 }
 
+impl Default for Scene {
+    fn default() -> Scene {
+        let lookfrom = Vec3::new(20., 20., 20.);
+        let lookat = Vec3::new(0., 0., 0.);
+        let dist_to_focus = (lookfrom - lookat).length();
+        let aperture = 0.1;
+        let time_min = 0.;
+        let time_max = 1.;
+        let camera = Camera::new(
+            lookfrom,
+            lookat,
+            Vec3::new(0., 1., 0.),
+            70.,
+            1.,
+            aperture,
+            dist_to_focus,
+            time_min,
+            time_max,
+        );
+        Scene {
+            world: Box::new(Sphere::new(
+                Vec3::new(0., 0., 0.),
+                1.0,
+                Lambertian::new(ConstantTexture::new([0., 1., 0.])),
+            )),
+            camera,
+            subsamples: 0,
+            num_threads: None,
+            width: 0,
+            height: 0,
+            global_illumination: false,
+            env_map: None,
+        }
+    }
+}
+
 // color will trace ray up to 50 bounces deep accumulating color as it goes.  If
 // global_illumination is true, a default light background color is assumed and will light the
 // world.  If false, it is expected the scene has emissive light sources.

rtiow/src/scenes/bench.rs

@@ -72,7 +72,6 @@ pub fn new(opt: &Opt) -> Scene {
         num_threads: opt.num_threads,
         width: opt.width,
         height: opt.height,
-        global_illumination: true,
-        env_map: None,
+        ..Default::default()
     }
 }

rtiow/src/scenes/book.rs

@@ -56,6 +56,7 @@ pub fn new(opt: &Opt) -> Scene {
         height: opt.height,
         global_illumination: true,
         env_map: Some(EnvMap::new(skybox)),
+        ..Default::default()
     }
 }
 

rtiow/src/scenes/bvh.rs

@@ -66,7 +66,6 @@ pub fn new(opt: &Opt) -> Scene {
         num_threads: opt.num_threads,
         width: opt.width,
         height: opt.height,
-        global_illumination: true,
-        env_map: None,
+        ..Default::default()
     }
 }

rtiow/src/scenes/cornell_box.rs

@@ -134,6 +134,6 @@ pub fn new(opt: &Opt) -> Scene {
         width: opt.width,
         height: opt.height,
         global_illumination: false,
-        env_map: None,
+        ..Default::default()
     }
 }

rtiow/src/scenes/cornell_smoke.rs

@@ -119,7 +119,6 @@ pub fn new(opt: &Opt) -> Scene {
         num_threads: opt.num_threads,
         width: opt.width,
         height: opt.height,
-        global_illumination: false,
-        env_map: None,
+        ..Default::default()
     }
 }

rtiow/src/scenes/final_scene.rs

@@ -172,7 +172,6 @@ pub fn new(opt: &Opt) -> Scene {
         num_threads: opt.num_threads,
         width: opt.width,
         height: opt.height,
-        global_illumination: false,
-        env_map: None,
+        ..Default::default()
     }
 }

rtiow/src/scenes/mandelbrot.rs

@@ -152,7 +152,6 @@ pub fn new(opt: &Opt) -> Scene {
         num_threads: opt.num_threads,
         width: opt.width,
         height: opt.height,
-        global_illumination: false,
-        env_map: None,
+        ..Default::default()
     }
 }

rtiow/src/scenes/perlin_debug.rs

@@ -69,6 +69,6 @@ pub fn new(opt: &Opt) -> Scene {
         width: opt.width,
         height: opt.height,
         global_illumination: true,
-        env_map: None,
+        ..Default::default()
     }
 }

rtiow/src/scenes/test.rs

@@ -145,7 +145,6 @@ pub fn new(opt: &Opt) -> Scene {
         num_threads: opt.num_threads,
         width: opt.width,
         height: opt.height,
-        global_illumination: false,
-        env_map: None,
+        ..Default::default()
     }
 }

rtiow/src/scenes/tutorial.rs

@@ -74,6 +74,6 @@ pub fn new(opt: &Opt) -> Scene {
         width: opt.width,
         height: opt.height,
         global_illumination: true,
-        env_map: None,
+        ..Default::default()
     }
 }