Fullres book cover and add timing.

Squelch clippy warning in camera.rs.

rtiow/src/bin/tracer.rs

@@ -1,6 +1,8 @@
 extern crate rand;
 extern crate rtiow;
 
+use std::time::Instant;
+
 use rand::Rng;
 
 use rtiow::camera::Camera;
@@ -101,9 +103,10 @@ fn random_scene() -> Vec<Box<Hit>> {
 }
 
 fn main() -> Result<(), std::io::Error> {
+    let start = Instant::now();
     let mut rng = rand::thread_rng();
-    let nx = 200;
-    let ny = 100;
+    let nx = 1200;
+    let ny = 800;
     let ns = 100;
     let (cam, world) = if BOOK_COVER {
         let lookfrom = Vec3::new(13., 2., 3.);
@@ -184,5 +187,11 @@ fn main() -> Result<(), std::io::Error> {
             println!("{} {} {}", ir, ig, ib);
         }
     }
+    let runtime = start.elapsed();
+    eprintln!(
+        "Render time {}.{} seconds",
+        runtime.as_secs(),
+        runtime.subsec_millis()
+    );
     Ok(())
 }

rtiow/src/camera.rs

@@ -29,7 +29,6 @@ pub struct Camera {
     vertical: Vec3,
     u: Vec3,
     v: Vec3,
-    w: Vec3,
     lens_radius: f32,
 }
 
@@ -59,7 +58,6 @@ impl Camera {
             horizontal: 2. * half_width * focus_dist * u,
             vertical: 2. * half_height * focus_dist * v,
             origin,
-            w: (lookfrom - lookat).unit_vector(),
             u: cross(vup, w).unit_vector(),
             v: cross(w, u),
             lens_radius: aperture / 2.,