diff --git a/rtiow/renderer/src/aabb.rs b/rtiow/renderer/src/aabb.rs
index 0aded58..f03c164 100644
--- a/rtiow/renderer/src/aabb.rs
+++ b/rtiow/renderer/src/aabb.rs
@@ -71,6 +71,8 @@ impl AABB {
         self.bounds[1]
     }
 
+    // TODO(wathiede): implement branchless https://tavianator.com/cgit/dimension.git/tree/libdimension/bvh/bvh.c#n194
+
     pub fn hit(&self, r: Ray, t_min: f32, t_max: f32) -> bool {
         self.hit_simd(r, t_min, t_max)
         //self.hit_naive(r, t_min, t_max)
@@ -152,7 +154,7 @@ impl AABB {
         unsafe {
             use std::arch::x86_64::*;
             let o4 = _mm_set_ps(0., r.origin.z, r.origin.y, r.origin.x);
-            let d4 = _mm_set_ps(0., r.direction.z, r.direction.y, r.direction.x);
+            let d4 = _mm_set_ps(0., r.inv_direction.z, r.inv_direction.y, r.inv_direction.x);
             let bmin4 = _mm_set_ps(0., self.min().z, self.min().y, self.min().x);
             let bmax4 = _mm_set_ps(0., self.max().z, self.max().y, self.max().x);
             let mask4 = _mm_cmpeq_ps(_mm_setzero_ps(), _mm_set_ps(1., 0., 0., 0.));
@@ -162,10 +164,9 @@ impl AABB {
             let vmin4 = _mm_min_ps(t1, t2);
             let vmax4: (f32, f32, f32, f32) = std::mem::transmute(vmax4);
             let vmin4: (f32, f32, f32, f32) = std::mem::transmute(vmin4);
-            let tmax = min(vmax4.0, min(vmax4.1, vmax4.2));
-            let tmin = max(vmin4.0, max(vmin4.1, vmin4.2));
-            //tmax >= tmin && tmin < r.time && tmax > t_min
-            t_min <= tmin && tmin <= t_max
+            let tmax = min(min(vmax4.0, min(vmax4.1, vmax4.2)), t_max);
+            let tmin = max(max(vmin4.0, max(vmin4.1, vmin4.2)), t_min);
+            tmin <= tmax
         }
     }
 
@@ -209,34 +210,91 @@ mod tests {
 
     macro_rules! hit_test {
         ($($name:ident,)*) => {
-            mod hit {
-                use super::*;
-                $(
-                    #[test]
-                    fn $name() {
-                        let t_min = 0.001;
-                        let t_max = f32::MAX;
-                        let bb = AABB::new([1., -1., -1.], [3., 1., 1.]);
-                        // Hit
-                        let r = Ray::new([0., 0., 0.], [1., 0., 0.], 0.5);
-                        assert!(bb.$name(r, t_min, t_max));
+            $(
+                mod $name {
+                    use super::*;
+                    const T_MIN: f32 = 0.001;
+                    const T_MAX: f32 = f32::MAX;
+
+                    fn test_bb() -> AABB {
+                        AABB::new([-1., -1., -1.], [1., 1., 1.])
                     }
-                )*
-            }
-            mod miss {
-                use super::*;
-                $(
+
                     #[test]
-                    fn $name() {
-                        let t_min = 0.001;
-                        let t_max = f32::MAX;
-                        let bb = AABB::new([1., -1., -1.], [3., 1., 1.]);
-                        // Miss
-                        let r = Ray::new([0., 0., 0.], [-1., 0., 0.], 0.5);
-                        assert!(!bb.$name(r, t_min, t_max));
+                    fn hit_front() {
+                        let bb = test_bb();
+                        let r = Ray::new([-2., 0., 0.], [1., 0., 0.], 0.5);
+                        assert!(bb.$name(r, T_MIN, T_MAX));
                     }
-                )*
-            }
+                    #[test]
+                    fn hit_back() {
+                        let bb = test_bb();
+                        let r = Ray::new([2., 0., 0.], [-1., 0., 0.], 0.5);
+                        assert!(bb.$name(r, T_MIN, T_MAX));
+                    }
+                    #[test]
+                    fn hit_top() {
+                        let bb = test_bb();
+                        let r = Ray::new([0., 2., 0.], [0., -1., 0.], 0.5);
+                        assert!(bb.$name(r, T_MIN, T_MAX));
+                    }
+                    #[test]
+                    fn hit_bottom() {
+                        let bb = test_bb();
+                        let r = Ray::new([0., -2., 0.], [0., 1., 0.], 0.5);
+                        assert!(bb.$name(r, T_MIN, T_MAX));
+                    }
+                    #[test]
+                    fn hit_left() {
+                        let bb = test_bb();
+                        let r = Ray::new([0., 0., -2.], [0., 0., 1.], 0.5);
+                        assert!(bb.$name(r, T_MIN, T_MAX));
+                    }
+                    #[test]
+                    fn hit_right() {
+                        let bb = test_bb();
+                        let r = Ray::new([0., 0., 2.], [0., 0., -1.], 0.5);
+                        assert!(bb.$name(r, T_MIN, T_MAX));
+                    }
+
+                    #[test]
+                    fn miss_front() {
+                        let bb = test_bb();
+                        let r = Ray::new([0., 1.1, -1.1], [0., -1., 0.], 0.5);
+                        assert!(!bb.$name(r, T_MIN, T_MAX));
+                    }
+                    #[test]
+                    fn miss_back() {
+                        let bb = test_bb();
+                        let r = Ray::new([0., 1.1, 1.1], [0., -1., 0.], 0.5);
+                        assert!(!bb.$name(r, T_MIN, T_MAX));
+                    }
+                    #[test]
+                    fn miss_top() {
+                        let bb = test_bb();
+                        let r = Ray::new([0., 1.1, -1.1], [0., 0., 1.], 0.5);
+                        assert!(!bb.$name(r, T_MIN, T_MAX));
+                    }
+                    #[test]
+                    fn miss_bottom() {
+                        let bb = test_bb();
+                        let r = Ray::new([0., -1.1, -1.1], [0., 0., 1.], 0.5);
+                        assert!(!bb.$name(r, T_MIN, T_MAX));
+                    }
+                    #[test]
+                    fn miss_left() {
+                        let bb = test_bb();
+                        let r = Ray::new([-1.1, 0., -1.1], [0., 0., 1.], 0.5);
+                        assert!(!bb.$name(r, T_MIN, T_MAX));
+                    }
+                    #[test]
+                    fn miss_right() {
+                        let bb = test_bb();
+                        let r = Ray::new([1.1, 0., -1.1], [0., 0., 1.], 0.5);
+                        assert!(!bb.$name(r, T_MIN, T_MAX));
+                    }
+                }
+            )*
         }
     }
 
diff --git a/rtiow/renderer/src/ray.rs b/rtiow/renderer/src/ray.rs
index f250646..72bc4b7 100644
--- a/rtiow/renderer/src/ray.rs
+++ b/rtiow/renderer/src/ray.rs
@@ -5,6 +5,9 @@ pub struct Ray {
     pub origin: Vec3,
     pub direction: Vec3,
     pub time: f32,
+
+    // Precache 1/direction, a single ray intersects multiple AABB's, and divides are more
+    // expensive than multiplies.
     pub inv_direction: Vec3,
     pub sign: [usize; 3],
 }
@@ -14,7 +17,7 @@ impl Ray {
     where
         V: Into<Vec3>,
     {
-        let direction = direction.into();
+        let direction: Vec3 = direction.into();
         let origin = origin.into();
         let inv = 1. / direction;
         Ray {
diff --git a/rtiow/renderer/src/scenes/stltest.rs b/rtiow/renderer/src/scenes/stltest.rs
index a11803a..c2d2e68 100644
--- a/rtiow/renderer/src/scenes/stltest.rs
+++ b/rtiow/renderer/src/scenes/stltest.rs
@@ -41,7 +41,9 @@ pub fn new(opt: &Opt) -> Scene {
     };
 
     let stl_cube = STL::parse(
-        BufReader::new(Cursor::new(include_bytes!("../../stls/20mm cube.stl"))),
+        BufReader::new(Cursor::new(include_bytes!(
+            "../../stls/stanford_dragon-lowres.stl"
+        ))),
         false,
     )
     .expect("failed to parse cube");
@@ -106,7 +108,8 @@ pub fn new(opt: &Opt) -> Scene {
                 &stl_cube,
                 Lambertian::new(ConstantTexture::new(Vec3::new(0.6, 0.6, 0.6))),
             ),
-            200.,
+            //1.,
+            250.,
         )),
     ];
     let world: Box<dyn Hit> = if opt.use_accel {