diff --git a/src/sc_sacd.cpp b/src/sc_sacd.cpp
index a7bebfe..765444f 100644
--- a/src/sc_sacd.cpp
+++ b/src/sc_sacd.cpp
@@ -65,19 +65,33 @@ std::vector<SC_SACD_Vec3> SC_SACD_Get_Box_Normals(
   std::vector<SC_SACD_Vec3> normals;
 
   normals.emplace_back(SC_SACD_Vec3{1.0F, 0.0F, 0.0F});
-  normals.back() = SC_SACD_Vec3_Rotate(normals.back(), box->x_radians,
-                                       box->y_radians, box->z_radians);
+  normals.back() = box->transform * normals.back();
 
   normals.emplace_back(SC_SACD_Vec3{0.0F, 1.0F, 0.0F});
-  normals.back() = SC_SACD_Vec3_Rotate(normals.back(), box->x_radians,
-                                       box->y_radians, box->z_radians);
+  normals.back() = box->transform * normals.back();
 
   normals.emplace_back(SC_SACD_Vec3{0.0F, 0.0F, 1.0F});
-  normals.back() = SC_SACD_Vec3_Rotate(normals.back(), box->x_radians,
-                                       box->y_radians, box->z_radians);
+  normals.back() = box->transform * normals.back();
+
+  return normals;
+}
+
+std::vector<SC_SACD_Vec3> SC_SACD_Get_Box_Normals_Normalized(
+    const SC_SACD_Generic_Box *box) {
+  std::vector<SC_SACD_Vec3> normals;
+
+  normals.emplace_back(SC_SACD_Vec3{1.0F, 0.0F, 0.0F});
+  normals.back() = box->transform * normals.back();
+  normals.back() = normals.back() / SC_SACD_Vec3_Length(normals.back());
+
+  normals.emplace_back(SC_SACD_Vec3{0.0F, 1.0F, 0.0F});
+  normals.back() = box->transform * normals.back();
+  normals.back() = normals.back() / SC_SACD_Vec3_Length(normals.back());
+
+  normals.emplace_back(SC_SACD_Vec3{0.0F, 0.0F, 1.0F});
+  normals.back() = box->transform * normals.back();
+  normals.back() = normals.back() / SC_SACD_Vec3_Length(normals.back());
 
-  // Not normalizing the normals on purpose for optimization. It should already
-  // be normalized as each normal is a rotated unit vector.
   return normals;
 }
 
@@ -85,55 +99,61 @@ std::vector<SC_SACD_Vec3> SC_SACD_Get_Box_Corners(
     const SC_SACD_Generic_Box *box) {
   std::vector<SC_SACD_Vec3> corners;
 
-  SC_SACD_Vec3 pos{box->x, box->y, box->z};
+  corners.push_back(box->transform * SC_SACD_Vec3{-box->width / 2.0F,
+                                                  -box->height / 2.0F,
+                                                  -box->depth / 2.0F});
+  corners.back().x += box->x;
+  corners.back().y += box->y;
+  corners.back().z += box->z;
 
-  corners.push_back(
-      SC_SACD_Vec3_Rotate(SC_SACD_Vec3{-box->width / 2.0F, -box->height / 2.0F,
-                                       -box->depth / 2.0F},
-                          box->x_radians, box->y_radians, box->z_radians) +
-      pos);
+  corners.push_back(box->transform * SC_SACD_Vec3{box->width / 2.0F,
+                                                  -box->height / 2.0F,
+                                                  -box->depth / 2.0F});
+  corners.back().x += box->x;
+  corners.back().y += box->y;
+  corners.back().z += box->z;
 
-  corners.push_back(
-      SC_SACD_Vec3_Rotate(SC_SACD_Vec3{box->width / 2.0F, -box->height / 2.0F,
-                                       -box->depth / 2.0F},
-                          box->x_radians, box->y_radians, box->z_radians) +
-      pos);
+  corners.push_back(box->transform * SC_SACD_Vec3{-box->width / 2.0F,
+                                                  box->height / 2.0F,
+                                                  -box->depth / 2.0F});
+  corners.back().x += box->x;
+  corners.back().y += box->y;
+  corners.back().z += box->z;
 
-  corners.push_back(
-      SC_SACD_Vec3_Rotate(SC_SACD_Vec3{-box->width / 2.0F, box->height / 2.0F,
-                                       -box->depth / 2.0F},
-                          box->x_radians, box->y_radians, box->z_radians) +
-      pos);
+  corners.push_back(box->transform * SC_SACD_Vec3{box->width / 2.0F,
+                                                  box->height / 2.0F,
+                                                  -box->depth / 2.0F});
+  corners.back().x += box->x;
+  corners.back().y += box->y;
+  corners.back().z += box->z;
 
-  corners.push_back(
-      SC_SACD_Vec3_Rotate(SC_SACD_Vec3{box->width / 2.0F, box->height / 2.0F,
-                                       -box->depth / 2.0F},
-                          box->x_radians, box->y_radians, box->z_radians) +
-      pos);
+  corners.push_back(box->transform * SC_SACD_Vec3{-box->width / 2.0F,
+                                                  -box->height / 2.0F,
+                                                  box->depth / 2.0F});
+  corners.back().x += box->x;
+  corners.back().y += box->y;
+  corners.back().z += box->z;
 
-  corners.push_back(
-      SC_SACD_Vec3_Rotate(SC_SACD_Vec3{-box->width / 2.0F, -box->height / 2.0F,
-                                       box->depth / 2.0F},
-                          box->x_radians, box->y_radians, box->z_radians) +
-      pos);
+  corners.push_back(box->transform * SC_SACD_Vec3{box->width / 2.0F,
+                                                  -box->height / 2.0F,
+                                                  box->depth / 2.0F});
+  corners.back().x += box->x;
+  corners.back().y += box->y;
+  corners.back().z += box->z;
 
-  corners.push_back(
-      SC_SACD_Vec3_Rotate(SC_SACD_Vec3{box->width / 2.0F, -box->height / 2.0F,
-                                       box->depth / 2.0F},
-                          box->x_radians, box->y_radians, box->z_radians) +
-      pos);
+  corners.push_back(box->transform * SC_SACD_Vec3{-box->width / 2.0F,
+                                                  box->height / 2.0F,
+                                                  box->depth / 2.0F});
+  corners.back().x += box->x;
+  corners.back().y += box->y;
+  corners.back().z += box->z;
 
-  corners.push_back(
-      SC_SACD_Vec3_Rotate(SC_SACD_Vec3{-box->width / 2.0F, box->height / 2.0F,
-                                       box->depth / 2.0F},
-                          box->x_radians, box->y_radians, box->z_radians) +
-      pos);
-
-  corners.push_back(
-      SC_SACD_Vec3_Rotate(SC_SACD_Vec3{box->width / 2.0F, box->height / 2.0F,
-                                       box->depth / 2.0F},
-                          box->x_radians, box->y_radians, box->z_radians) +
-      pos);
+  corners.push_back(box->transform * SC_SACD_Vec3{box->width / 2.0F,
+                                                  box->height / 2.0F,
+                                                  box->depth / 2.0F});
+  corners.back().x += box->x;
+  corners.back().y += box->y;
+  corners.back().z += box->z;
 
   return corners;
 }
@@ -226,9 +246,7 @@ int SC_SACD_AABB_Generic_Box_Collision(const SC_SACD_AABB_Box *a,
   a_conv.width = a->width;
   a_conv.height = a->height;
   a_conv.depth = a->depth;
-  a_conv.x_radians = 0.0F;
-  a_conv.y_radians = 0.0F;
-  a_conv.z_radians = 0.0F;
+  a_conv.transform = SC_SACD_Mat4_Identity();
   return SC_SACD_Generic_Box_Collision(&a_conv, b);
 }
 
@@ -478,3 +496,7 @@ SC_SACD_Vec3 SC_SACD_Closest_Point(const SC_SACD_Vec3 *pos,
       SC_SACD_Dot_Product(*dir, *dir);
   return *pos + *dir * alpha;
 }
+
+float SC_SACD_Vec3_Length(const SC_SACD_Vec3 vec) {
+  return std::sqrt(SC_SACD_Dot_Product(vec, vec));
+}
diff --git a/src/sc_sacd.h b/src/sc_sacd.h
index 3ad66b9..7ba1c7e 100644
--- a/src/sc_sacd.h
+++ b/src/sc_sacd.h
@@ -55,10 +55,8 @@ typedef struct SC_SACD_EXPORT SC_SACD_Generic_Box {
   float height;
   /// z-axis depth.
   float depth;
-  /// Rotation about center of box about axis.
-  float x_radians;
-  float y_radians;
-  float z_radians;
+  /// Local transform; expects center of box as origin.
+  SC_SACD_Mat4 transform;
 } SC_SACD_Generic_Box;
 
 typedef struct SC_SACD_EXPORT SC_SACD_Sphere {
@@ -106,6 +104,7 @@ SC_SACD_EXPORT SC_SACD_Mat4 SC_SACD_Mat4_Mult(const SC_SACD_Mat4 *a,
 SC_SACD_EXPORT SC_SACD_Vec3 SC_SACD_Mat4_Vec3_Mult(const SC_SACD_Mat4 *mat,
                                                    const SC_SACD_Vec3 vec);
 
+/// Rotates by x-axis first, then y-axis, then finally z-axis.
 SC_SACD_EXPORT SC_SACD_Vec3 SC_SACD_Vec3_Rotate(const SC_SACD_Vec3 vec,
                                                 float x_axis, float y_axis,
                                                 float z_axis);
@@ -124,6 +123,8 @@ SC_SACD_EXPORT SC_SACD_Vec3 SC_SACD_Closest_Point(const SC_SACD_Vec3 *pos,
                                                   const SC_SACD_Vec3 *dir,
                                                   const SC_SACD_Vec3 *point);
 
+SC_SACD_EXPORT float SC_SACD_Vec3_Length(const SC_SACD_Vec3 vec);
+
 #ifdef __cplusplus
 }
 #endif
diff --git a/src/test.cpp b/src/test.cpp
index 58e9c2d..b9b32c0 100644
--- a/src/test.cpp
+++ b/src/test.cpp
@@ -96,8 +96,10 @@ int main() {
 
   // Test Separating_Axis_Collision check.
   {
-    SC_SACD_Generic_Box a{0.0F, 0.0F, 0.0F, 1.0F, 1.0F, 1.0F, 0.0F, 0.0F, 0.0F};
-    SC_SACD_Generic_Box b{0.0F, 0.0F, 0.0F, 1.0F, 1.0F, 1.0F, 0.0F, 0.0F, 0.0F};
+    SC_SACD_Generic_Box a{
+        0.0F, 0.0F, 0.0F, 1.0F, 1.0F, 1.0F, SC_SACD_Mat4_Identity()};
+    SC_SACD_Generic_Box b{
+        0.0F, 0.0F, 0.0F, 1.0F, 1.0F, 1.0F, SC_SACD_Mat4_Identity()};
 
     CHECK_TRUE(SC_SACD_Generic_Box_Collision(&a, &b));
 
@@ -106,37 +108,37 @@ int main() {
     b.x = -1.1F;
     CHECK_FALSE(SC_SACD_Generic_Box_Collision(&a, &b));
 
-    a.z_radians = std::numbers::pi_v<float> / 4.0F;
-    b.z_radians = a.z_radians;
+    a.transform = SC_SACD_Rotation_Mat4_ZAxis(std::numbers::pi_v<float> / 4.0F);
+    b.transform = a.transform;
     CHECK_TRUE(SC_SACD_Generic_Box_Collision(&a, &b));
     b.x = 1.1F;
     CHECK_TRUE(SC_SACD_Generic_Box_Collision(&a, &b));
 
     b.x = 0.0F;
     b.y = 1.1F;
-    a.z_radians = 0.0F;
-    b.z_radians = 0.0F;
+    a.transform = SC_SACD_Mat4_Identity();
+    b.transform = a.transform;
     CHECK_FALSE(SC_SACD_Generic_Box_Collision(&a, &b));
     b.y = -1.1F;
     CHECK_FALSE(SC_SACD_Generic_Box_Collision(&a, &b));
 
-    a.z_radians = std::numbers::pi_v<float> / 4.0F;
-    b.z_radians = a.z_radians;
+    a.transform = SC_SACD_Rotation_Mat4_ZAxis(std::numbers::pi_v<float> / 4.0F);
+    b.transform = a.transform;
     CHECK_TRUE(SC_SACD_Generic_Box_Collision(&a, &b));
     b.y = 1.1F;
     CHECK_TRUE(SC_SACD_Generic_Box_Collision(&a, &b));
 
     b.y = 0.0F;
-    a.z_radians = 0.0F;
-    b.z_radians = 0.0F;
+    a.transform = SC_SACD_Mat4_Identity();
+    b.transform = a.transform;
 
     b.z = 1.1F;
     CHECK_FALSE(SC_SACD_Generic_Box_Collision(&a, &b));
     b.z = -1.1F;
     CHECK_FALSE(SC_SACD_Generic_Box_Collision(&a, &b));
 
-    a.y_radians = std::numbers::pi_v<float> / 4.0F;
-    b.y_radians = a.y_radians;
+    a.transform = SC_SACD_Rotation_Mat4_YAxis(std::numbers::pi_v<float> / 4.0F);
+    b.transform = a.transform;
     CHECK_TRUE(SC_SACD_Generic_Box_Collision(&a, &b));
     b.z = 1.1F;
     CHECK_TRUE(SC_SACD_Generic_Box_Collision(&a, &b));
@@ -236,9 +238,14 @@ int main() {
   // Test Sphere/Generic_Box collision check.
   {
     SC_SACD_Sphere sphere{0.0F, 0.0F, 0.0F, 1.0F};
-    SC_SACD_Generic_Box box{0.0F, 0.0F, 0.0F,
-                            2.0F, 2.0F, 2.0F,
-                            0.0F, 0.0F, std::numbers::pi_v<float> / 4.0F};
+    SC_SACD_Generic_Box box{
+        0.0F,
+        0.0F,
+        0.0F,
+        2.0F,
+        2.0F,
+        2.0F,
+        SC_SACD_Rotation_Mat4_ZAxis(std::numbers::pi_v<float> / 4.0F)};
 
     CHECK_TRUE(SC_SACD_Sphere_Box_Collision(&sphere, &box));