Add (yet) unused AABB implementation

src/aabb.rs

@@ -0,0 +1,49 @@
+use cgmath::Vector3;
+use std::ops::{Div, Sub};
+
+pub struct Aabb<T> {
+    pub min: Vector3<T>,
+    pub max: Vector3<T>,
+}
+
+impl<T: Ord + Copy + Sub<Output = T> + Div<Output = T>> Aabb<T> {
+    pub fn intersects_ray(
+        &self,
+        ray_origin: Vector3<T>,
+        ray_direction: Vector3<T>,
+    ) -> Option<(T, T)> {
+        let mut t_min = (self.min.x - ray_origin.x) / ray_direction.x;
+        let mut t_max = (self.max.x - ray_origin.x) / ray_direction.x;
+        if t_min > t_max {
+            std::mem::swap(&mut t_min, &mut t_max);
+        }
+
+        let mut ty_min = (self.min.y - ray_origin.y) / ray_direction.y;
+        let mut ty_max = (self.max.y - ray_origin.y) / ray_direction.y;
+        if ty_min > ty_max {
+            std::mem::swap(&mut ty_min, &mut ty_max);
+        }
+
+        if t_min > ty_max || ty_min > t_max {
+            return None;
+        }
+
+        t_min = T::max(t_min, ty_min);
+        t_max = T::min(t_min, ty_max);
+
+        let mut tz_min = (self.min.z - ray_origin.z) / ray_direction.z;
+        let mut tz_max = (self.max.z - ray_origin.z) / ray_direction.z;
+        if tz_min > tz_max {
+            std::mem::swap(&mut tz_min, &mut tz_max);
+        }
+
+        if t_min > tz_max || tz_min > t_max {
+            return None;
+        }
+
+        t_min = T::max(t_min, tz_min);
+        t_max = T::max(t_max, tz_max);
+
+        Some((t_min, t_max))
+    }
+}