Cleanup: spelling in comments

Also update viewport comments.

source/blender/blenkernel/BKE_collection.h

@@ -130,9 +130,9 @@ bool BKE_collection_object_add(struct Main *bmain,
                                struct Collection *collection,
                                struct Object *ob);
 /**
- * Same as #BKE_collection_object_add, but uncondionnaly adds the object to the given collection.
+ * Same as #BKE_collection_object_add, but unconditionally adds the object to the given collection.
  *
- * NOTE: required in certain cases, like do-versionning or complex ID management tasks.
+ * NOTE: required in certain cases, like do-versioning or complex ID management tasks.
  */
 bool BKE_collection_object_add_notest(struct Main *bmain,
                                       struct Collection *collection,

source/blender/blenkernel/intern/mesh_iterators.c

@@ -34,7 +34,7 @@
 
 #include "MEM_guardedalloc.h"
 
-/* General note on iterating vers/loops/edges/polys and end mode.
+/* General note on iterating verts/loops/edges/polys and end mode.
  *
  * The edit mesh pointer is set for both final and cage meshes in both cases when there are
  * modifiers applied and not. This helps consistency of checks in the draw manager, where the

source/blender/editors/space_view3d/view3d_draw.c

@@ -1036,7 +1036,7 @@ static void draw_rotation_guide(const RegionView3D *rv3d)
   negate_v3_v3(o, rv3d->ofs);
 
   GPU_blend(GPU_BLEND_ALPHA);
-  GPU_depth_mask(false); /* don't overwrite zbuf */
+  GPU_depth_mask(false); /* Don't overwrite the Z-buffer. */
 
   GPUVertFormat *format = immVertexFormat();
   uint pos = GPU_vertformat_attr_add(format, "pos", GPU_COMP_F32, 3, GPU_FETCH_FLOAT);

source/blender/editors/space_view3d/view3d_navigate.c

@@ -254,7 +254,7 @@ bool view3d_orbit_calc_center(bContext *C, float r_dyn_ofs[3])
     }
   }
   else {
-    /* If there's no selection, lastofs is unmodified and last value since static */
+    /* If there's no selection, `lastofs` is unmodified and last value since static. */
     is_set = calculateTransformCenter(C, V3D_AROUND_CENTER_MEDIAN, lastofs, NULL);
   }
 
@@ -300,7 +300,7 @@ void viewops_data_create(bContext *C,
   if (viewops_flag & VIEWOPS_FLAG_DEPTH_NAVIGATE) {
     float fallback_depth_pt[3];
 
-    view3d_operator_needs_opengl(C); /* needed for zbuf drawing */
+    view3d_operator_needs_opengl(C); /* Needed for Z-buffer drawing. */
 
     negate_v3_v3(fallback_depth_pt, rv3d->ofs);
 
@@ -356,8 +356,8 @@ void viewops_data_create(bContext *C,
   if (viewops_flag & VIEWOPS_FLAG_DEPTH_NAVIGATE) {
     if (vod->use_dyn_ofs) {
       if (rv3d->is_persp) {
-        float my_origin[3]; /* original G.vd->ofs */
-        float my_pivot[3];  /* view */
+        float my_origin[3]; /* Original #RegionView3D.ofs. */
+        float my_pivot[3];  /* View pivot. */
         float dvec[3];
 
         /* locals for dist correction */

source/blender/editors/space_view3d/view3d_navigate_ndof.c

@@ -205,7 +205,7 @@ static void view3d_ndof_orbit(const struct wmNDOFMotionData *ndof,
     /* Perform the orbital rotation */
     angle = ndof->dt * rot[1];
 
-    /* update the onscreen doo-dad */
+    /* Update the onscreen axis-angle indicator. */
     rv3d->rot_angle = angle;
     rv3d->rot_axis[0] = 0;
     rv3d->rot_axis[1] = 0;
@@ -222,7 +222,7 @@ static void view3d_ndof_orbit(const struct wmNDOFMotionData *ndof,
     /* transform rotation axis from view to world coordinates */
     mul_qt_v3(view_inv, axis);
 
-    /* update the onscreen doo-dad */
+    /* Update the onscreen axis-angle indicator. */
     rv3d->rot_angle = angle;
     copy_v3_v3(rv3d->rot_axis, axis);
 
@@ -251,7 +251,7 @@ void view3d_ndof_fly(const wmNDOFMotionData *ndof,
   float view_inv[4];
   invert_qt_qt_normalized(view_inv, rv3d->viewquat);
 
-  rv3d->rot_angle = 0.0f; /* disable onscreen rotation doo-dad */
+  rv3d->rot_angle = 0.0f; /* Disable onscreen rotation indicator. */
 
   if (has_translate) {
     /* ignore real 'dist' since fly has its own speed settings,

source/blender/editors/space_view3d/view3d_navigate_zoom.c

@@ -469,7 +469,6 @@ static int viewzoom_exec(bContext *C, wmOperator *op)
 
   if (delta < 0) {
     const float step = 1.2f;
-    /* this min and max is also in viewmove() */
     if (use_cam_zoom) {
       view_zoom_to_window_xy_camera(scene, depsgraph, v3d, region, step, zoom_xy);
     }

source/blender/editors/transform/transform.h

@@ -580,11 +580,11 @@ typedef struct TransInfo {
   /** Mouse side of the current frame, 'L', 'R' or 'B' */
   char frame_side;
 
-  /** copy from G.vd, prevents feedback. */
+  /** copy from #RegionView3D, prevents feedback. */
   float viewmat[4][4];
   /** and to make sure we don't have to. */
   float viewinv[4][4];
-  /** access G.vd from other space types. */
+  /** Access #RegionView3D from other space types. */
   float persmat[4][4];
   float persinv[4][4];
   short persp;