diff --git a/rust/src/geometry.rs b/rust/src/geometry.rs
index 1b5b33b26..10850f198 100644
--- a/rust/src/geometry.rs
+++ b/rust/src/geometry.rs
@@ -1,6 +1,6 @@
 use core::f32;
 
-use nalgebra_glm::{make_mat4, make_vec3, triangle_normal, vec2, vec3, vec4, Mat4, Vec3, Vec2};
+use nalgebra_glm::{make_mat4, make_vec3, triangle_normal, vec2, vec4, Mat4, Vec3, Vec2};
 use wasm_bindgen::prelude::*;
 
 #[derive(Default, Debug, Clone)]
@@ -10,6 +10,11 @@ pub struct Plane {
 }
 
 impl Plane {
+    pub fn normalized(&self) -> Plane {
+        let mag = self.normal.magnitude();
+        Plane { normal: self.normal / mag, d: self.d / mag }
+    }
+
     pub fn negate(&mut self) {
         self.normal.neg_mut();
         self.d *= -1.0;
@@ -86,6 +91,13 @@ impl AABB {
         }
     }
 
+    pub fn get_closest_point_along_direction(&self, dir: &Vec3) -> Vec3 {
+        let x = if dir.x >= 0.0 { self.max.x } else { self.min.x };
+        let y = if dir.y >= 0.0 { self.max.y } else { self.min.y };
+        let z = if dir.z >= 0.0 { self.max.z } else { self.min.z };
+        Vec3::new(x, y, z)
+    }
+
     pub fn transform(&mut self, mat: &Mat4) {
         // Transforming Axis-Aligned Bounding Boxes from Graphics Gems.
         let min = self.min.clone();
@@ -160,7 +172,7 @@ pub struct ConvexHull {
 impl ConvexHull {
     pub fn contains_point(&self, p: &Vec3) -> bool {
         for plane in &self.planes {
-            if plane.distance(p) > 0.0 {
+            if plane.distance(p) < 0.0 {
                 return false;
             }
         }
@@ -170,44 +182,13 @@ impl ConvexHull {
     pub fn intersect_aabb(&self, aabb: &AABB) -> IntersectionState {
         let mut result = IntersectionState::Inside;
         for plane in &self.planes {
-            let nearest = vec3(
-                if plane.normal.x >= 0.0 {
-                    aabb.min.x
-                } else {
-                    aabb.max.x
-                },
-                if plane.normal.y >= 0.0 {
-                    aabb.min.y
-                } else {
-                    aabb.max.y
-                },
-                if plane.normal.z >= 0.0 {
-                    aabb.min.z
-                } else {
-                    aabb.max.z
-                },
-            );
-            if plane.distance(&nearest) > 0.0 {
+            let nearest = aabb.get_closest_point_along_direction(&plane.normal);
+            if plane.distance(&nearest) < 0.0 {
                 return IntersectionState::Outside;
             }
-            let farthest = vec3(
-                if plane.normal.x >= 0.0 {
-                    aabb.max.x
-                } else {
-                    aabb.min.x
-                },
-                if plane.normal.y >= 0.0 {
-                    aabb.max.y
-                } else {
-                    aabb.min.y
-                },
-                if plane.normal.z >= 0.0 {
-                    aabb.max.z
-                } else {
-                    aabb.min.z
-                },
-            );
-            if plane.distance(&farthest) > 0.0 {
+
+            let farthest = aabb.get_closest_point_along_direction(&-plane.normal);
+            if plane.distance(&farthest) < 0.0 {
                 result = IntersectionState::Intersection;
             }
         }
@@ -218,9 +199,9 @@ impl ConvexHull {
         let mut result = IntersectionState::Inside;
         for plane in &self.planes {
             let dist = plane.distance(center);
-            if dist > radius {
+            if dist < radius {
                 return IntersectionState::Outside;
-            } else if dist > -radius {
+            } else if dist < -radius {
                 result = IntersectionState::Intersection;
             }
         }
diff --git a/rust/src/wow/wmo.rs b/rust/src/wow/wmo.rs
index 6fde9c099..31a7e243c 100644
--- a/rust/src/wow/wmo.rs
+++ b/rust/src/wow/wmo.rs
@@ -553,10 +553,10 @@ impl PortalData {
 
             let mut plane = Plane::default();
             plane.set_tri(eye, &a, &b);
-            if plane.distance(&test_point) > 0.0 {
+            if plane.distance(&test_point) < 0.0 {
                 plane.negate();
             }
-            assert!(plane.distance(&test_point) <= 0.0);
+            assert!(plane.distance(&test_point) >= 0.0);
             result.planes.push(plane);
         }
         result
diff --git a/src/Geometry.ts b/src/Geometry.ts
index 1a8c21026..333cb12a7 100644
--- a/src/Geometry.ts
+++ b/src/Geometry.ts
@@ -315,22 +315,21 @@ export class Frustum {
 
     public updateClipFrustum(m: ReadonlyMat4, clipSpaceNearZ: GfxClipSpaceNearZ): void {
         // http://www8.cs.umu.se/kurser/5DV051/HT12/lab/plane_extraction.pdf
-        // Note that we look down the -Z axis, rather than the +Z axis, so we have to invert all of our planes...
 
         const h = this.convexHull;
         h.clear();
-        h.push_plane(-(m[3] + m[0]), -(m[7] + m[4]), -(m[11] + m[8]) , -(m[15] + m[12])); // Left
-        h.push_plane(-(m[3] + m[1]), -(m[7] + m[5]), -(m[11] + m[9]) , -(m[15] + m[13])); // Top
-        h.push_plane(-(m[3] - m[0]), -(m[7] - m[4]), -(m[11] - m[8]) , -(m[15] - m[12])); // Right
-        h.push_plane(-(m[3] - m[1]), -(m[7] - m[5]), -(m[11] - m[9]) , -(m[15] - m[13])); // Bottom
+        h.push_plane(m[3] + m[0], m[7] + m[4], m[11] + m[8], m[15] + m[12]); // Left
+        h.push_plane(m[3] + m[1], m[7] + m[5], m[11] + m[9], m[15] + m[13]); // Top
+        h.push_plane(m[3] - m[0], m[7] - m[4], m[11] - m[8], m[15] - m[12]); // Right
+        h.push_plane(m[3] - m[1], m[7] - m[5], m[11] - m[9], m[15] - m[13]); // Bottom
 
         if (clipSpaceNearZ === GfxClipSpaceNearZ.NegativeOne) {
-            h.push_plane(-(m[3] + m[2]), -(m[7] + m[6]), -(m[11] + m[10]), -(m[15] + m[14])); // Near
+            h.push_plane(m[3] + m[2], m[7] + m[6], m[11] + m[10], m[15] + m[14]); // Near
         } else if (clipSpaceNearZ === GfxClipSpaceNearZ.Zero) {
-            h.push_plane(-(m[2]), -(m[6]), -(m[10]), -(m[14])); // Near
+            h.push_plane(m[2], m[6], m[10], m[14]); // Near
         }
 
-        h.push_plane(-(m[3] - m[2]), -(m[7] - m[6]), -(m[11] - m[10]), -(m[15] - m[14])); // Far
+        h.push_plane(m[3] - m[2], m[7] - m[6], m[11] - m[10], m[15] - m[14]); // Far
     }
 
     public copy(o: Frustum): void {