ft: 4: ray class + simpl gradient

src/main.rs

@@ -1,31 +1,62 @@
 #![feature(core_float_math)]
 
+mod ray;
 mod vec3;
 
-use crate::vec3::Vec3;
+use std::cmp::max;
+
+use crate::ray::Ray;
+use crate::vec3::{Colour, Vec3};
 use log::info;
 use pretty_env_logger;
 
+fn ray_colour(r: &Ray) -> Colour {
+    let unit_dir = r.dir().get_unit();
+    let a = 0.5 * (unit_dir.y() + 1.);
+
+    (1.0 - a) * Colour::new(1., 1., 1.) + a * Colour::new(0.5, 0.7, 1.0)
+}
+
 fn main() {
-    let v = Vec3::rgb(255., 0., 255.);
+    // use structs so rust-analyzer can provide lsp
+    let v = Vec3::new(255., 0., 255.);
+    let _ = Ray::new(v.clone(), v.clone());
+
     pretty_env_logger::init();
 
-    let image_width = 256;
-    let image_height = 256;
+    let aspect_ratio = 16. / 9.;
+    let image_width = 400;
+    let image_height = max(1, (image_width as f32 / aspect_ratio) as u32);
+
+    //camera
+    let focal_length = 1.;
+    let viewport_height = 2.;
+    let viewport_width = viewport_height * (image_width as f32 / image_height as f32);
+    let camera_center = Vec3::nil();
+
+    //viewport
+    let viewport_u = Vec3::new(viewport_width as f32, 0., 0.);
+    let viewport_v = Vec3::new(0., -viewport_height as f32, 0.);
+
+    let pixel_delta_u = viewport_u / image_width as f32;
+    let pixel_delta_v = viewport_v / image_height as f32;
+
+    let viewport_upper_left =
+        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);
 
     let mut imgbuf = image::ImageBuffer::new(image_width, image_height);
 
+    // render
     for j in 0..image_height {
         info!("{}\tScanlines remaining.", (image_height - j));
         for i in 0..image_width {
-            let rgb = Vec3::rgb(
-                i as f32 / (image_width - 1) as f32,
-                j as f32 / (image_height - 1) as f32,
-                0.0,
-            );
+            let pixel_center = pixel00_loc + (i * pixel_delta_u) + (j * pixel_delta_v);
+            let ray_dir = pixel_center - camera_center;
+            let r = Ray::new(camera_center, ray_dir);
 
             let pixel = imgbuf.get_pixel_mut(i, j);
-            *pixel = rgb.output();
+            *pixel = ray_colour(&r).output();
         }
     }