Fix #130907: Use Blender Action name as the UsdSkelAnimation name

Rather than using a default "Anim" name when exporting armature
animations, use the animation's Action name instead. Likewise use the
UsdSkelAnimation name for the Action's name during import.

Blendshapes/shapekeys still use the default "Anim" name as there's no
action for these situations.

Pull Request: https://projects.blender.org/blender/blender/pulls/131021

source/blender/io/usd/intern/usd_blend_shape_utils.cc

@@ -304,19 +304,26 @@ void remap_blend_shape_anim(pxr::UsdStageRefPtr stage,
                             const pxr::SdfPath &skel_path,
                             const pxr::SdfPathSet &mesh_paths)
 {
-  pxr::UsdSkelSkeleton skel = pxr::UsdSkelSkeleton::Get(stage, skel_path);
+  pxr::UsdSkelBindingAPI skel_api = pxr::UsdSkelBindingAPI::Get(stage, skel_path);
 
-  if (!skel) {
+  if (!skel_api) {
     CLOG_WARN(&LOG, "Couldn't get skeleton from path %s", skel_path.GetAsString().c_str());
     return;
   }
 
-  /* Create the animation. */
-  pxr::SdfPath anim_path = skel_path.AppendChild(usdtokens::Anim);
-  const pxr::UsdSkelAnimation anim = pxr::UsdSkelAnimation::Define(stage, anim_path);
+  /* Use existing animation if possible, otherwise create a new one. */
+  pxr::UsdPrim anim_prim;
+  pxr::UsdSkelAnimation anim;
+  if (skel_api.GetAnimationSource(&anim_prim)) {
+    anim = pxr::UsdSkelAnimation(anim_prim);
+  }
+  else {
+    pxr::SdfPath anim_path = skel_path.AppendChild(usdtokens::Anim);
+    anim = pxr::UsdSkelAnimation::Define(stage, anim_path);
+  }
 
   if (!anim) {
-    CLOG_WARN(&LOG, "Couldn't define animation at path %s", anim_path.GetAsString().c_str());
+    CLOG_WARN(&LOG, "Couldn't get animation under skeleton %s", skel_path.GetAsString().c_str());
     return;
   }
 

source/blender/io/usd/intern/usd_skel_convert.cc

@@ -27,6 +27,7 @@
 #include "BKE_deform.hh"
 #include "BKE_fcurve.hh"
 #include "BKE_key.hh"
+#include "BKE_lib_id.hh"
 #include "BKE_modifier.hh"
 #include "BKE_object_deform.h"
 #include "BKE_report.hh"
@@ -143,6 +144,7 @@ void import_skeleton_curves(Main *bmain,
 
   /* Create the action on the armature. */
   bAction *act = blender::animrig::id_action_ensure(bmain, &arm_obj->id);
+  BKE_id_rename(*bmain, act->id, anim_query.GetPrim().GetName().GetText());
 
   /* Create the curves. */
 

source/blender/io/usd/intern/usd_writer_armature.cc

@@ -4,6 +4,9 @@
 
 #include "usd_writer_armature.hh"
 #include "usd_armature_utils.hh"
+#include "usd_utils.hh"
+
+#include "ANIM_action.hh"
 
 #include "BKE_action.hh"
 
@@ -19,10 +22,6 @@
 #include "CLG_log.h"
 static CLG_LogRef LOG = {"io.usd"};
 
-namespace usdtokens {
-static const pxr::TfToken Anim("Anim", pxr::TfToken::Immortal);
-}  // namespace usdtokens
-
 /**
  * Get the pose matrix for the given channel.
  * The matrix is computed relative to its parent, if a parent exists.
@@ -110,7 +109,7 @@ static void initialize(const Object *obj,
 
   if (skel_anim) {
     usd_skel_api.CreateAnimationSourceRel().SetTargets(
-        pxr::SdfPathVector({pxr::SdfPath(usdtokens::Anim)}));
+        pxr::SdfPathVector({pxr::SdfPath(skel_anim.GetPath().GetName())}));
     create_pose_joints(skel_anim, *obj, deform_bones, allow_unicode);
   }
 }
@@ -169,9 +168,15 @@ void USDArmatureWriter::do_write(HierarchyContext &context)
 
   pxr::UsdSkelAnimation skel_anim;
 
+  const bool allow_unicode = usd_export_context_.export_params.allow_unicode;
+
   if (usd_export_context_.export_params.export_animation) {
+    /* Use the action name as the animation name. */
+    const animrig::Action *action = animrig::get_action(context.object->id);
+    const pxr::TfToken anim_name(make_safe_name(action->id.name + 2, allow_unicode));
+
     /* Create the skeleton animation primitive as a child of the skeleton. */
-    pxr::SdfPath anim_path = usd_export_context_.usd_path.AppendChild(usdtokens::Anim);
+    pxr::SdfPath anim_path = usd_export_context_.usd_path.AppendChild(anim_name);
     skel_anim = pxr::UsdSkelAnimation::Define(stage, anim_path);
 
     if (!skel_anim) {
@@ -180,7 +185,6 @@ void USDArmatureWriter::do_write(HierarchyContext &context)
     }
   }
 
-  const bool allow_unicode = usd_export_context_.export_params.allow_unicode;
   Map<StringRef, const Bone *> *deform_map = usd_export_context_.export_params.only_deform_bones ?
                                                  &deform_map_ :
                                                  nullptr;

tests/python/bl_usd_export_test.py

@@ -753,6 +753,7 @@ class USDExportTest(AbstractUSDTest):
         self.assertEqual(prim.GetTypeName(), "Skeleton")
         prim_skel = UsdSkel.BindingAPI(prim)
         anim = UsdSkel.Animation(prim_skel.GetAnimationSource())
+        self.assertEqual(anim.GetPrim().GetName(), "ArmatureAction_001")
         self.assertEqual(anim.GetJointsAttr().Get(),
                          ['Bone',
                           'Bone/Bone_001',

tests/python/bl_usd_import_test.py

@@ -533,6 +533,7 @@ class USDImportTest(AbstractUSDTest):
         ob_arm = bpy.data.objects["column_anim_armature"]
         ob_arm2_side_a = bpy.data.objects["side_a"]
         ob_arm2_side_b = bpy.data.objects["side_b"]
+        self.assertEqual(bpy.data.objects["Armature"].animation_data.action.name, "ArmatureAction_001")
 
         bpy.context.scene.frame_set(1)
         self.assertEqual(len(ob_xform.constraints), 1)
@@ -678,7 +679,7 @@ class USDImportTest(AbstractUSDTest):
             self.assertAlmostEqual(mesh_obj.vertex_groups['Elbow'].weight(
                 8 + i), 1.0, 2, "Unexpected weight for Elbow deform vert")
 
-        action = bpy.data.actions['SkelAction']
+        action = bpy.data.actions['Anim1']
 
         # Verify the Elbow joint rotation animation.
         curve_path = 'pose.bones["Elbow"].rotation_quaternion'