eoc6: implement challenge for end of chapter 6.

rtchallenge/examples/eoc6.rs

@@ -0,0 +1,56 @@
+use anyhow::Result;
+
+use rtchallenge::{
+    canvas::Canvas,
+    lights::PointLight,
+    materials::{lighting, Material},
+    rays::Ray,
+    spheres::{intersect, Sphere},
+    tuples::{Color, Tuple},
+};
+
+fn main() -> Result<()> {
+    let w = 640;
+    let h = w;
+    let bg = Color::new(0.2, 0.2, 0.2);
+    let mut c = Canvas::new(w, h, bg);
+    let ray_origin = Tuple::point(0., 0., -5.);
+    let wall_z = 10.;
+    let wall_size = 7.;
+    let pixel_size = wall_size / w as f32;
+    let half = wall_size / 2.;
+    let mut shape = Sphere::default();
+    shape.material = Material {
+        color: Color::new(1., 0.2, 1.),
+        specular: 0.5,
+        diffuse: 0.7,
+        shininess: 30.,
+        ..Material::default()
+    };
+    let light_position = Tuple::point(-10., 10., -10.);
+    let light_color = Color::new(1., 1., 1.);
+    let light = PointLight::new(light_position, light_color);
+
+    for y in 0..h {
+        let world_y = half - pixel_size * y as f32;
+        for x in 0..w {
+            let world_x = -half + pixel_size * x as f32;
+            let position = Tuple::point(world_x, world_y, wall_z);
+            let direction = (position - ray_origin).normalize();
+            let r = Ray::new(ray_origin, direction);
+            let xs = intersect(&shape, &r);
+            if let Some(hit) = xs.hit() {
+                let point = r.position(hit.t);
+                let normal = hit.object.normal_at(point);
+                let eye = -r.direction;
+                let color = lighting(&hit.object.material, &light, point, eye, normal);
+                c.set(x, y, color);
+            }
+        }
+    }
+
+    let path = "/tmp/eoc6.png";
+    println!("saving output to {}", path);
+    c.write_to_file(path)?;
+    Ok(())
+}