Cleanup: spelling in comments

source/blender/blenkernel/intern/constraint.c

@@ -147,7 +147,7 @@ bConstraintOb *BKE_constraints_make_evalob(
           cob->rotOrder = ob->rotmode;
         }
         else {
-          /* Quats/Axis-Angle, so Eulers should just use default order */
+          /* Quaternion/Axis-Angle, so Eulers should just use default order. */
           cob->rotOrder = EULER_ORDER_DEFAULT;
         }
         copy_m4_m4(cob->matrix, ob->object_to_world);
@@ -171,7 +171,7 @@ bConstraintOb *BKE_constraints_make_evalob(
           cob->rotOrder = cob->pchan->rotmode;
         }
         else {
-          /* Quats, so eulers should just use default order */
+          /* Quaternion, so eulers should just use default order */
           cob->rotOrder = EULER_ORDER_DEFAULT;
         }
 

source/blender/blenkernel/intern/curve.cc

@@ -2166,7 +2166,10 @@ static void bevel_list_apply_tilt(BevList *bl)
     bevp2++;
   }
 }
-/* smooth quats, this function should be optimized, it can get slow with many iterations. */
+/**
+ * Smooth quaternions, this function should be optimized,
+ * it can get slow with many iterations.
+ */
 static void bevel_list_smooth(BevList *bl, int smooth_iter)
 {
   BevPoint *bevp2, *bevp1, *bevp0;
@@ -2199,7 +2202,7 @@ static void bevel_list_smooth(BevList *bl, int smooth_iter)
     copy_qt_qt(bevp0_quat, bevp0->quat);
 
     while (nr--) {
-      /* interpolate quats */
+      /* Interpolate quaternions. */
       float zaxis[3] = {0, 0, 1}, cross[3], q2[4];
       interp_qt_qtqt(q, bevp0_quat, bevp2->quat, 0.5);
       normalize_qt(q);
@@ -2314,7 +2317,7 @@ static void make_bevel_list_3D_minimum_twist(BevList *bl)
     bevp_last = bevp_first;
     bevp_last--;
 
-    /* quats and vec's are normalized, should not need to re-normalize */
+    /* Quaternions and vectors are normalized, should not need to re-normalize. */
     mul_qt_v3(bevp_first->quat, vec_1);
     mul_qt_v3(bevp_last->quat, vec_2);
     normalize_v3(vec_1);

source/blender/blenkernel/intern/object.cc

@@ -2998,7 +2998,7 @@ void BKE_object_rot_to_mat3(const Object *ob, float mat[3][3], bool use_drot)
    * with the rotation matrix to yield the appropriate rotation
    */
 
-  /* rotations may either be quats, eulers (with various rotation orders), or axis-angle */
+  /* Rotations may either be quaternions, eulers (with various rotation orders), or axis-angle. */
   if (ob->rotmode > 0) {
     /* Euler rotations
      * (will cause gimbal lock, but this can be alleviated a bit with rotation orders). */

source/blender/blenkernel/intern/paint.cc

@@ -1372,9 +1372,7 @@ bool paint_calculate_rake_rotation(UnifiedPaintSettings *ups,
     float r = paint_rake_rotation_spacing(ups, brush);
     float rotation;
 
-    /* Use a smaller limit if the stroke hasn't started
-     * to prevent excessive preroll.
-     */
+    /* Use a smaller limit if the stroke hasn't started to prevent excessive pre-roll. */
     if (!stroke_has_started) {
       r = min_ff(r, 4.0f);
     }

source/blender/blenlib/tests/BLI_math_rotation_test.cc

@@ -25,7 +25,7 @@ static void test_quat_to_mat_to_quat(float w, float x, float y, float z)
   quat_to_mat3(matrix, norm_quat);
   mat3_normalized_to_quat(out_quat, matrix);
 
-  /* The expected result is flipped (each orientation corresponds to 2 quats) */
+  /* The expected result is flipped (each orientation corresponds to 2 quaternions). */
   if (w < 0) {
     mul_qt_fl(norm_quat, -1);
   }

source/blender/editors/space_view3d/view3d_buttons.c

@@ -1614,7 +1614,7 @@ static void v3d_posearmature_buts(uiLayout *layout, Object *ob)
 
   col = uiLayoutColumn(layout, false);
 
-  /* XXX: RNA buts show data in native types (i.e. quats, 4-component axis/angle, etc.)
+  /* XXX: RNA buts show data in native types (i.e. quaternion, 4-component axis/angle, etc.)
    * but old-school UI shows in eulers always. Do we want to be able to still display in Eulers?
    * Maybe needs RNA/UI options to display rotations as different types. */
   v3d_transform_butsR(col, &pchanptr);

source/blender/editors/space_view3d/view3d_navigate_smoothview.cc

@@ -300,8 +300,8 @@ void ED_view3d_smooth_view_ex(
 
     sms.time_allowed = double(smooth_viewtx / 1000.0);
 
-    /* If this is view rotation only we can decrease the time allowed by the angle between quats
-     * this means small rotations won't lag. */
+    /* If this is view rotation only we can decrease the time allowed by the angle between
+     * quaternions this means small rotations won't lag. */
     if (sview->quat && !sview->ofs && !sview->dist) {
       /* scale the time allowed by the rotation */
       /* 180deg == 1.0 */

source/blender/editors/space_view3d/view3d_navigate_walk.cc

@@ -475,7 +475,7 @@ enum {
   WALK_CONFIRM = 2,
 };
 
-/* keep the previous speed until user changes userpreferences */
+/* Keep the previous speed until user changes preferences. */
 static float base_speed = -1.0f;
 static float userdef_speed = -1.0f;
 

source/blender/geometry/intern/mesh_merge_by_distance.cc

@@ -389,8 +389,8 @@ static Vector<WeldEdge> weld_edge_ctx_alloc_and_find_collapsed(Span<int2> edges,
  * \param weld_edges: Candidate edges for merging (edges that don't collapse and that have at least
  *                    one weld vertex).
  *
- * \return r_edge_dest_map: Map of indices pointing the source edges to eacth targed.
- * \return r_edge_double_kill_len: Number of duplicate edges to be destroyed.
+ * \param r_edge_dest_map: Resulting map of indices pointing the source edges to each target.
+ * \param r_edge_double_kill_len: Resulting number of duplicate edges to be destroyed.
  */
 static void weld_edge_find_doubles(Span<WeldEdge> weld_edges,
                                    int mvert_num,

source/blender/ikplugin/intern/itasc_plugin.cpp

@@ -863,7 +863,7 @@ static bool joint_callback(const iTaSC::Timestamp &timestamp,
       axis_angle_to_mat3(rmat, &chan->quat[1], chan->quat[0]);
     }
     else {
-      /* quats are normalized before use to eliminate scaling issues */
+      /* Quaternions are normalized before use to eliminate scaling issues. */
       normalize_qt(chan->quat);
       quat_to_mat3(rmat, chan->quat);
     }

source/blender/windowmanager/intern/wm_files_link.c

@@ -224,7 +224,7 @@ static int wm_link_append_exec(bContext *C, wmOperator *op)
       filepath, libname, &group, &name);
 
   /* NOTE: Need to also check filepath, as typically libname is an empty string here (when trying
-   * to append from current file from the filebrowser e.g.). */
+   * to append from current file from the file-browser e.g.). */
   if (BLI_path_cmp(BKE_main_blendfile_path(bmain), filepath) == 0 ||
       BLI_path_cmp(BKE_main_blendfile_path(bmain), libname) == 0)
   {