Add Light trait and PointLight instance

src/render.rs

@@ -0,0 +1,25 @@
+extern crate nalgebra as na;
+
+use std::cmp::Ordering;
+
+use na::*;
+use na::geometry::Point3;
+
+use crate::types::*;
+use crate::object::*;
+
+fn trace(ray: Ray, objects: &Vec<Object>) -> Option<(&Object, f32)> {
+    objects.iter()
+           .filter_map(|obj| obj.intersect(ray)
+                                .map(|x| (obj, x)))
+           .min_by(|a, b| a.1.partial_cmp(&b.1).unwrap_or(Ordering::Equal))
+}
+
+pub fn cast_ray(ray: Ray, scene: &Scene) -> Color {
+    if let Some((obj, dist)) = trace(ray, &scene.objects) {
+        let point = ray.project(dist);
+
+        obj.getcolor(point)
+    }
+    else { scene.background }
+}