Implemented bounding spheres for objects

src/object/bound.rs

@@ -0,0 +1,37 @@
+extern crate nalgebra as na;
+
+use na::distance;
+use na::geometry::Point3;
+
+use crate::types::Ray;
+
+// A bounding sphere, used for
+// intersection test optimization.
+#[derive(Debug)]
+pub struct Bound {
+    pub center: Point3<f32>,
+    pub radius: f32,
+
+    // If true, then the bounding sphere is disabled.
+    pub bypass: bool
+}
+
+impl Bound {
+    pub fn is_intersected(&self, ray: Ray) -> bool {
+
+        if self.bypass { return true; }
+
+        let l = ray.origin - self.center;
+
+        let b_2 = ray.direction.dot(&l);
+        let c = l.norm_squared() - self.radius * self.radius;
+
+        let discr = b_2 * b_2 * c;
+
+        discr >= 0.0
+    }
+
+    pub fn contains(&self, point: &Point3<f32>) -> bool { distance(&self.center, point) < self.radius }
+
+    pub fn bypass() -> Self { Bound { center: Point3::origin(), radius: 0.0, bypass: true } }
+}