4 files changed, 47 insertions, 1 deletions
diff --git a/src/core/hittable.rs b/src/core/hittable.rs
new file mode 100644
index 0000000..20c82f7
--- /dev/null
+++ b/src/core/hittable.rs
@@ -0,0 +1,23 @@
+use crate::core::{Vector3f, Ray};
+
+/// Returns the context of a intersection
+pub struct Intersection {
+    /// Normal vector at intersection
+    pub n: Vector3f,
+    pub p: Vector3f,
+}
+
+impl Intersection {
+    pub fn norm_against_ray(&self, r: &Ray) -> Vector3f {
+        if self.n.dot(&r.direction) < 0.0 {
+            self.n
+        } else {
+            -self.n
+        }
+    }
+}
+
+/// Defines a common trait for objects in the scene
+pub trait Hittable {
+    fn intersect(&self, ray: &Ray) -> Option<Intersection>;
+}
diff --git a/src/core/mod.rs b/src/core/mod.rs
index 5723b2d..c2b3771 100644
--- a/src/core/mod.rs
+++ b/src/core/mod.rs
@@ -6,6 +6,7 @@ pub mod vector2;
 pub mod vector3;
 pub mod bound;
 pub mod spectrum;
+pub mod hittable;
 mod ray;
 
 pub use vector2::{Vector2i, Vector2f};
@@ -13,3 +14,4 @@ pub use vector3::Vector3f;
 pub use bound::{Bound2i, Bound2f};
 pub use spectrum::Spectrum;
 pub use ray::Ray;
+pub use hittable::{Hittable, Intersection};
diff --git a/src/core/spectrum.rs b/src/core/spectrum.rs
index 727a1b6..9cca7dc 100644
--- a/src/core/spectrum.rs
+++ b/src/core/spectrum.rs
@@ -41,6 +41,18 @@ impl std::ops::Mul<Float> for Spectrum {
     }
 }
 
+impl std::ops::Mul for Spectrum {
+    type Output = Spectrum;
+
+    fn mul(self, op: Self) -> Self::Output {
+        Self::Output::new_rgb(
+            self.c[0] * op.c[0],
+            self.c[1] * op.c[1],
+            self.c[2] * op.c[2],
+            )
+    }
+}
+
 impl std::ops::Div<Float> for Spectrum {
     type Output = Spectrum;
 
diff --git a/src/core/vector3.rs b/src/core/vector3.rs
index ef067aa..ff5a678 100644
--- a/src/core/vector3.rs
+++ b/src/core/vector3.rs
@@ -1,7 +1,7 @@
 //! Implements 3d vectors
 //!
 //! Also add more 3d math things needed for shading and 3d calculations.
-use crate::{Float, Number};
+use crate::{Float, Number, NEAR_ZERO};
 use std::ops::{Mul, Sub, Add, DivAssign, Neg};
 use std::fmt;
 
@@ -149,4 +149,13 @@ impl Vector3f {
             )
 
     }
+
+    /// Check if vector is close to [0, 0, 0]
+    ///
+    /// This is based on the NEAR_ZERO constant
+    pub fn near_zero(&self) -> bool {
+        (self.x.abs() < NEAR_ZERO) &&
+            (self.y.abs() < NEAR_ZERO) &&
+            (self.z.abs() < NEAR_ZERO)
+    }
 }