1 files changed, 69 insertions, 0 deletions
diff --git a/src/core/bound3.rs b/src/core/bound3.rs
new file mode 100644
index 0000000..7f54e03
--- /dev/null
+++ b/src/core/bound3.rs
@@ -0,0 +1,69 @@
+//! Implements 3d axis aligned bounding box
+use crate::{Number, Float};
+use super::vector3::Vector3;
+use crate::core::{min, max};
+use crate::core::Ray;
+
+#[derive(Clone)]
+pub struct Bound3<T: Number> {
+    pub min: Vector3<T>,
+    pub max: Vector3<T>
+}
+
+pub type Bound3f = Bound3<Float>;
+
+impl<T: Number> Bound3<T> {
+    /// Creates a bound from two points
+    pub fn new(p0: Vector3<T>, p1: Vector3<T>) -> Self {
+        // Elliminate some code duplication here
+        let min = Vector3::new_xyz(
+            min(p0.x, p1.x),
+            min(p0.y, p1.y),
+            min(p0.z, p1.z)
+            );
+        let max = Vector3::new_xyz(
+            max(p0.x, p1.x),
+            max(p0.y, p1.y),
+            max(p0.z, p1.z)
+            );
+
+        Self {min, max}
+    }
+}
+
+impl Bound3f {
+    /// Calculate whether there is a intersect between a bounding box and a ray
+    ///
+    /// # Examples:
+    ///
+    /// ```
+    /// use rendering::core::{Bound3f, Vector3f, Ray};
+    /// let b = Bound3f::new(Vector3f::new(7.0), Vector3f::new(10.0));
+    /// let r1 = Ray::new_to(Vector3f::new(0.0), Vector3f::new(5.0));
+    /// let r3 = Ray::new(Vector3f::new_xyz(-1.0, 0.0, 0.0), Vector3f::new_xyz(1.0, 0.0, 0.0));
+    ///
+    /// assert!(b.intersect(&r1));
+    /// assert!(!b.intersect(&r3));
+    /// ```
+    pub fn intersect(&self, ray: &Ray) -> bool {
+        // Method stolen from Ray tracing the next week.
+        // They mention its from pixar
+        for i in 0..3 {
+            let inv = 1.0 / ray.direction[i];
+            let mut t0 = (self.min[i] - ray.origin[i]) * inv;
+            let mut t1 = (self.max[i] - ray.origin[i]) * inv;
+
+            if inv < 0.0 {
+                let tmp = t0;
+                t0 = t1;
+                t1 = tmp;
+            }
+
+            if t1 <= t0 {
+                return false;
+            }
+        }
+
+        return true;
+    }
+}