feat(raytracer): add minimal phong lighting demo

src/raytracer/plane.rs

@@ -0,0 +1,51 @@
+use super::types::{Intersect, Material, Point3, Vector3};
+
+extern crate nalgebra as na;
+
+/// An infinite plane in 3D space.
+pub struct Plane {
+    /// The position of the plane.
+    position: Point3,
+    /// The normal of the plane.
+    normal: Vector3,
+    /// The material of the plane.
+    material: Material,
+}
+
+impl Plane {
+    /// Create a new plane.
+    /// - `position` is the position of the plane.
+    /// - `normal` is the normal of the plane.
+    /// - `material` is the material of the plane.
+    pub fn new(position: Point3, normal: Vector3, material: Material) -> Plane {
+        Plane {
+            position,
+            normal,
+            material,
+        }
+    }
+}
+
+impl Intersect for Plane {
+    fn intersect<'a>(
+        &'a self,
+        ray: &super::types::Ray,
+    ) -> Option<(
+        Point3,
+        Vector3,
+        super::types::Scalar,
+        &'a super::types::Material,
+    )> {
+        let denom = self.normal.dot(&ray.direction);
+        if denom != 0.0 {
+            let d = self.normal.dot(&self.position.coords);
+            let t = (d - self.normal.dot(&ray.origin.coords)) / denom;
+
+            if t > 1e-5 {
+                let point = ray.origin + ray.direction * t;
+                return Some((point, self.normal, t, &self.material));
+            }
+        }
+        None
+    }
+}