Save .png output directly from rust.

rtiow/src/bin/tracer.rs

@@ -1,8 +1,10 @@
+extern crate image;
 extern crate rand;
 extern crate rtiow;
 
 use std::time::Instant;
 
+use image::RgbImage;
 use rand::Rng;
 
 use rtiow::camera::Camera;
@@ -105,9 +107,11 @@ fn random_scene() -> Vec<Box<Hit>> {
 fn main() -> Result<(), std::io::Error> {
     let start = Instant::now();
     let mut rng = rand::thread_rng();
-    let nx = 1200;
-    let ny = 800;
-    let ns = 100;
+    // Set to 1 to do full res.
+    let dev_factor = 4;
+    let nx = 1200 / dev_factor;
+    let ny = 800 / dev_factor;
+    let ns = 100 / dev_factor;
     let (cam, world) = if BOOK_COVER {
         let lookfrom = Vec3::new(13., 2., 3.);
         let lookat = Vec3::new(0., 0., 0.);
@@ -167,8 +171,9 @@ fn main() -> Result<(), std::io::Error> {
         ]);
         (cam, world)
     };
-    println!("P3\n{} {}\n255", nx, ny);
-    for j in (0..ny).rev() {
+
+    let mut img = RgbImage::new(nx, ny);
+    for j in 0..ny {
         for i in 0..nx {
             let mut col: Vec3 = Default::default();
             for _ in 0..ns {
@@ -181,10 +186,11 @@ fn main() -> Result<(), std::io::Error> {
             // Gamma correct, use gamma 2 correction, which is 1/gamma where gamma=2 which is 1/2
             // or sqrt.
             col = Vec3::new(col[0].sqrt(), col[1].sqrt(), col[2].sqrt());
-            let ir = (255.99 * col[0]) as u32;
-            let ig = (255.99 * col[1]) as u32;
-            let ib = (255.99 * col[2]) as u32;
-            println!("{} {} {}", ir, ig, ib);
+            let ir = (255.99 * col[0]) as u8;
+            let ig = (255.99 * col[1]) as u8;
+            let ib = (255.99 * col[2]) as u8;
+            // ny-j is to flip y-axis.
+            img.put_pixel(i, ny - j - 1, image::Rgb([ir, ig, ib]));
         }
     }
     let runtime = start.elapsed();
@@ -193,5 +199,10 @@ fn main() -> Result<(), std::io::Error> {
         runtime.as_secs(),
         runtime.subsec_millis()
     );
+
+    let path = "/tmp/test.png";
+    // Write the contents of this image to the Writer in PNG format.
+    img.save(path).unwrap();
+    eprintln!("Saved {}", path);
     Ok(())
 }