ft: 8: anti-aliasing

.gitignore

@@ -1 +1,2 @@
 /target
+output.png

src/camera.rs

@@ -11,6 +11,7 @@ use crate::{
 pub struct Camera {
     image_width: u32,
     image_height: u32,
+    anti_alias_rate: u32,
     center: Vec3,
     pixel00_loc: Vec3,
     pixel_delta_u: Vec3,
@@ -19,6 +20,9 @@ pub struct Camera {
 
 impl Camera {
     pub fn new(aspect_ratio: f32, image_width: u32) -> Camera {
+        Camera::new_aa(aspect_ratio, image_width, 1)
+    }
+    pub fn new_aa(aspect_ratio: f32, image_width: u32, anti_alias_rate: u32) -> Camera {
         let image_height = max(1, (image_width as f32 / aspect_ratio) as u32);
 
         //camera
@@ -34,13 +38,13 @@ impl Camera {
         let pixel_delta_u = viewport_u / image_width as f32;
         let pixel_delta_v = viewport_v / image_height as f32;
 
-        let viewport_upper_left =
+        let pixel00_loc =
             camera_center - Vec3::new(0., 0., focal_length) - viewport_u / 2 - viewport_v / 2;
-        let pixel00_loc = viewport_upper_left + 0.5 * (pixel_delta_u + pixel_delta_v);
 
         Camera {
             image_width: image_width,
             image_height: image_height,
+            anti_alias_rate: anti_alias_rate,
             center: camera_center,
             pixel00_loc: pixel00_loc,
             pixel_delta_u: pixel_delta_u,
@@ -55,13 +59,24 @@ impl Camera {
         for j in 0..self.image_height {
             info!("{}\tScanlines remaining.", (self.image_height - j));
             for i in 0..self.image_width {
-                let pixel_center =
+                let pixel_tl =
                     self.pixel00_loc + (i * self.pixel_delta_u) + (j * self.pixel_delta_v);
-                let ray_dir = pixel_center - self.center;
+
+                let mut pixel_colour = Colour::nil();
+                for y in 1..(self.anti_alias_rate + 1) {
+                    for x in 1..(self.anti_alias_rate + 1) {
+                        let pixel_loc = pixel_tl
+                            + (x * self.pixel_delta_u / (self.anti_alias_rate + 1) as f32)
+                            + (y * self.pixel_delta_v / (self.anti_alias_rate + 1) as f32);
+                        let ray_dir = pixel_loc - self.center;
                         let r = Ray::new(self.center, ray_dir);
+                        pixel_colour += self.ray_colour(&hittables, &r);
+                    }
+                }
 
                 let pixel = imgbuf.get_pixel_mut(i, j);
-                *pixel = self.ray_colour(&hittables, &r).output();
+                *pixel =
+                    (pixel_colour / (self.anti_alias_rate * self.anti_alias_rate) as f32).output();
             }
         }
 

src/main.rs

@@ -19,6 +19,6 @@ fn main() {
     world.push(Sphere::new(Vec3::new(0., 0., -0.1), 0.01));
     world.push(Sphere::new(Vec3::new(0., -100.5, -1.), 100.));
 
-    let c = Camera::new(16. / 9., 400);
+    let c = Camera::new_aa(16. / 9., 400, 2);
     c.render(&world);
 }

src/vec3.rs

@@ -67,9 +67,9 @@ impl Vec3 {
     }
 
     pub fn output(self) -> image::Rgb<u8> {
-        let ir = (255.599 * self.r) as u8;
+        let ir = (255.599 * self.r.clamp(0., 1.)) as u8;
-        let ig = (255.599 * self.g) as u8;
+        let ig = (255.599 * self.g.clamp(0., 1.)) as u8;
-        let ib = (255.599 * self.b) as u8;
+        let ib = (255.599 * self.b.clamp(0., 1.)) as u8;
 
         image::Rgb([ir, ig, ib])
     }