1 files changed, 40 insertions, 3 deletions
diff --git a/libdimension/dimension/object.h b/libdimension/dimension/object.h
index 267a515..794d99e 100644
--- a/libdimension/dimension/object.h
+++ b/libdimension/dimension/object.h
@@ -113,6 +113,25 @@ void dmnsn_delete_object(dmnsn_object *object);
  */
 void dmnsn_initialize_object(dmnsn_object *object);
 
+
+/**
+ * Transform a surface normal vector.
+ * @param[in] trans   The transformation matrix.
+ * @param[in] normal  The normal vector to transform
+ * @return The transformed normal vector.
+ */
+DMNSN_INLINE dmnsn_vector
+dmnsn_transform_normal(dmnsn_matrix trans, dmnsn_vector normal)
+{
+  return dmnsn_vector_normalize(
+    dmnsn_vector_sub(
+      dmnsn_transform_vector(trans, normal),
+      /* Optimized form of dmnsn_transform_vector(trans, dmnsn_zero) */
+      dmnsn_new_vector(trans.n[0][3], trans.n[1][3], trans.n[2][3])
+    )
+  );
+}
+
 /**
  * Appropriately transform a ray, then test for an intersection.
  * @param[in]  object        The object to test.
@@ -120,8 +139,21 @@ void dmnsn_initialize_object(dmnsn_object *object);
  * @param[out] intersection  Where to store the intersection details.
  * @return Whether there was an intersection.
  */
-bool dmnsn_object_intersection(const dmnsn_object *object, dmnsn_line line,
-                               dmnsn_intersection *intersection);
+DMNSN_INLINE bool
+dmnsn_object_intersection(const dmnsn_object *object, dmnsn_line line,
+                          dmnsn_intersection *intersection)
+{
+  dmnsn_line line_trans = dmnsn_transform_line(object->trans_inv, line);
+  if ((*object->intersection_fn)(object, line_trans, intersection)) {
+    /* Get us back into world coordinates */
+    intersection->ray    = line;
+    intersection->normal = dmnsn_transform_normal(object->trans,
+                                                  intersection->normal);
+    return true;
+  } else {
+    return false;
+  }
+}
 
 /**
  * Appropriately transform a point, then test for containment.
@@ -129,6 +161,11 @@ bool dmnsn_object_intersection(const dmnsn_object *object, dmnsn_line line,
  * @param[in] point   The point to test.
  * @return Whether \p point was inside \p object.
  */
-bool dmnsn_object_inside(const dmnsn_object *object, dmnsn_vector point);
+DMNSN_INLINE bool
+dmnsn_object_inside(const dmnsn_object *object, dmnsn_vector point)
+{
+  point = dmnsn_transform_vector(object->trans_inv, point);
+  return (*object->inside_fn)(object, point);
+}
 
 #endif /* DIMENSION_OBJECT_H */