Render sphere hits

The left sphere looks deformed, look into it.

src/lib.rs

@@ -281,20 +281,21 @@ pub fn posunit_to_unit(value: f32) -> f32 {
 
 pub struct Radians(pub f32);
 
-pub fn render(width: usize, height: usize) -> Image {
+pub fn render(spheres: &[Sphere], camera: &Camera, width: usize, height: usize) -> Image {
     let mut image = Image::new(width, height);
-    let max = (width * height) as f32;
     for i in 0..width {
         for j in 0..height {
-            image.set_color(
-                i,
-                j,
-                Color::new(
-                    i as f32 / width as f32,
-                    j as f32 / height as f32,
-                    i as f32 * j as f32 / max,
-                ),
+            // -1s here because we want to provide x and y coordinates between 0 and 1 inclusive
+            let ray = camera.screen_ray(
+                i as f32 / (width - 1) as f32,
+                j as f32 / (height - 1) as f32,
             );
+            let intersection = closest_intersection(&spheres, &ray);
+            let color = match intersection {
+                Intersection::None => Color::new_black(),
+                Intersection::Hit(_) => Color::new_red(),
+            };
+            image.set_color(i, j, color);
         }
     }
     image
@@ -390,4 +391,8 @@ impl Color {
     pub fn new_black() -> Color {
         Self::new(0.0, 0.0, 0.0)
     }
+
+    pub fn new_red() -> Color {
+        Self::new(1.0, 0.0, 0.0)
+    }
 }

src/main.rs

@@ -1,4 +1,4 @@
-use raytracer::{image_to_file, render};
+use raytracer::{image_to_file, render, Camera, Radians, Sphere, Vector};
 use std::env;
 use std::fs::File;
 use std::io::{self, Write};
@@ -20,6 +20,39 @@ fn main() {
         _ => Box::new(File::create(filename).expect("Cannot open file for writing")),
     };
 
-    let image = render(200, 100);
+    let spheres = [
+        Sphere {
+            center: Vector {
+                x: 0.0,
+                y: 0.0,
+                z: -5.0,
+            },
+            radius: 1.0,
+        },
+        Sphere {
+            center: Vector {
+                x: -3.0,
+                y: 1.0,
+                z: -5.0,
+            },
+            radius: 1.0,
+        },
+        Sphere {
+            center: Vector {
+                x: 5.0,
+                y: 1.0,
+                z: -10.0,
+            },
+            radius: 1.0,
+        },
+    ];
+    let camera = Camera {
+        position: Vector::zero(),
+        forward: -Vector::unitz(),
+        up: Vector::unity(),
+        aspect_ratio: 4.0 / 3.0,
+        fovx: Radians(90.0f32.to_radians()),
+    };
+    let image = render(&spheres, &camera, 800, 600);
     image_to_file(&image, &mut file);
 }