Refactor: Rename Object->obmat to Object->object_to_world

Motivation is to disambiguate on the naming level what the matrix
actually means. It is very easy to understand the meaning backwards,
especially since in Python the name goes the opposite way (it is
called `world_matrix` in the Python API).

It is important to disambiguate the naming without making developers
to look into the comment in the header file (which is also not super
clear either). Additionally, more clear naming facilitates the unit
verification (or, in this case, space validation) when reading an
expression.

This patch calls the matrix `object_to_world` which makes it clear
from the local code what is it exactly going on. This is only done
on DNA level, and a lot of local variables still follow the old
naming.

A DNA rename is setup in a way that there is no change on the file
level, so there should be no regressions at all.

The possibility is to add `_matrix` or `_mat` suffix to the name
to make it explicit that it is a matrix. Although, not sure if it
really helps the readability, or is it something redundant.

Differential Revision: https://developer.blender.org/D16328

1 files changed, 9 insertions, 8 deletions

diff --git a/source/blender/editors/space_view3d/view3d_utils.c b/source/blender/editors/space_view3d/view3d_utils.c
index 1fc16939f3f..fc26e6b4a06 100644
--- a/source/blender/editors/space_view3d/view3d_utils.c
+++ b/source/blender/editors/space_view3d/view3d_utils.c
@@ -281,7 +281,7 @@ void ED_view3d_clipping_calc(
   /* optionally transform to object space */
   if (ob) {
     float imat[4][4];
-    invert_m4_m4(imat, ob->obmat);
+    invert_m4_m4(imat, ob->object_to_world);
 
     for (int val = 0; val < 8; val++) {
       mul_m4_v3(imat, bb->vec[val]);
@@ -291,7 +291,7 @@ void ED_view3d_clipping_calc(
   /* verify if we have negative scale. doing the transform before cross
    * product flips the sign of the vector compared to doing cross product
    * before transform then, so we correct for that. */
-  int flip_sign = (ob) ? is_negative_m4(ob->obmat) : false;
+  int flip_sign = (ob) ? is_negative_m4(ob->object_to_world) : false;
 
   ED_view3d_clipping_calc_from_boundbox(planes, bb, flip_sign);
 }
@@ -466,7 +466,8 @@ void ED_view3d_persp_switch_from_camera(const Depsgraph *depsgraph,
 
   if (v3d->camera) {
     Object *ob_camera_eval = DEG_get_evaluated_object(depsgraph, v3d->camera);
-    rv3d->dist = ED_view3d_offset_distance(ob_camera_eval->obmat, rv3d->ofs, VIEW3D_DIST_FALLBACK);
+    rv3d->dist = ED_view3d_offset_distance(
+        ob_camera_eval->object_to_world, rv3d->ofs, VIEW3D_DIST_FALLBACK);
     ED_view3d_from_object(ob_camera_eval, rv3d->ofs, rv3d->viewquat, &rv3d->dist, NULL);
   }
 
@@ -558,7 +559,7 @@ void ED_view3d_camera_lock_init_ex(const Depsgraph *depsgraph,
     if (calc_dist) {
       /* using a fallback dist is OK here since ED_view3d_from_object() compensates for it */
       rv3d->dist = ED_view3d_offset_distance(
-          ob_camera_eval->obmat, rv3d->ofs, VIEW3D_DIST_FALLBACK);
+          ob_camera_eval->object_to_world, rv3d->ofs, VIEW3D_DIST_FALLBACK);
     }
     ED_view3d_from_object(ob_camera_eval, rv3d->ofs, rv3d->viewquat, &rv3d->dist, NULL);
   }
@@ -592,12 +593,12 @@ bool ED_view3d_camera_lock_sync(const Depsgraph *depsgraph, View3D *v3d, RegionV
 
       ED_view3d_to_m4(view_mat, rv3d->ofs, rv3d->viewquat, rv3d->dist);
 
-      normalize_m4_m4(tmat, ob_camera_eval->obmat);
+      normalize_m4_m4(tmat, ob_camera_eval->object_to_world);
 
       invert_m4_m4(imat, tmat);
       mul_m4_m4m4(diff_mat, view_mat, imat);
 
-      mul_m4_m4m4(parent_mat, diff_mat, root_parent_eval->obmat);
+      mul_m4_m4m4(parent_mat, diff_mat, root_parent_eval->object_to_world);
 
       BKE_object_tfm_protected_backup(root_parent, &obtfm);
       BKE_object_apply_mat4(root_parent, parent_mat, true, false);
@@ -1508,7 +1509,7 @@ void ED_view3d_to_m4(float mat[4][4], const float ofs[3], const float quat[4], c
 
 void ED_view3d_from_object(const Object *ob, float ofs[3], float quat[4], float *dist, float *lens)
 {
-  ED_view3d_from_m4(ob->obmat, ofs, quat, dist);
+  ED_view3d_from_m4(ob->object_to_world, ofs, quat, dist);
 
   if (lens) {
     CameraParams params;
@@ -1555,7 +1556,7 @@ static bool view3d_camera_to_view_selected_impl(struct Main *bmain,
       is_ortho_camera = true;
     }
 
-    copy_m4_m4(obmat_new, camera_ob_eval->obmat);
+    copy_m4_m4(obmat_new, camera_ob_eval->object_to_world);
     copy_v3_v3(obmat_new[3], co);
 
     /* only touch location */