Fix #145116: new FBX importer does not handle geometry transform + instancing properly

When instanced meshes were using FBX geometric transforms, the code
was not telling ufbx to create proper adjustment helper nodes due to
UFBX_GEOMETRY_TRANSFORM_HANDLING_MODIFY_GEOMETRY_NO_FALLBACK flag.
That flag was put in earlier, before import of armatures was solidified,
turns out using the proper flag (UFBX_GEOMETRY_TRANSFORM_HANDLING_MODIFY_GEOMETRY)
is not a problem anymore.

Pull Request: https://projects.blender.org/blender/blender/pulls/145527

source/blender/io/fbx/importer/fbx_import.cc

@@ -347,11 +347,7 @@ void importer_main(Main *bmain, Scene *scene, ViewLayer *view_layer, const FBXIm
   opts.clean_skin_weights = true;
   opts.use_blender_pbr_material = true;
 
-  /* Do geometry modifications for "geometric transforms" cases; when it cannot do that
-   * (e.g. instancing etc.), do not insert helper nodes to account for that. Helper nodes currently
-   * cause armatures/skins to not import correctly, when inserted in the middle of bone chain. */
-  opts.geometry_transform_handling = UFBX_GEOMETRY_TRANSFORM_HANDLING_MODIFY_GEOMETRY_NO_FALLBACK;
-
+  opts.geometry_transform_handling = UFBX_GEOMETRY_TRANSFORM_HANDLING_MODIFY_GEOMETRY;
   opts.pivot_handling = UFBX_PIVOT_HANDLING_ADJUST_TO_ROTATION_PIVOT;
 
   opts.space_conversion = UFBX_SPACE_CONVERSION_ADJUST_TRANSFORMS;

source/blender/io/fbx/importer/fbx_import_armature.cc

@@ -109,7 +109,15 @@ void ArmatureImportContext::create_armature_bones(const ufbx_node *node,
   bArmature *arm = static_cast<bArmature *>(arm_obj->data);
 
   /* Create an EditBone. */
-  EditBone *bone = ED_armature_ebone_add(arm, get_fbx_name(node->name, "Bone"));
+  std::string name;
+  if (node->is_geometry_transform_helper) {
+    /* Name geometry transform adjustment helpers with parent name and _GeomAdjust suffix. */
+    name = get_fbx_name(node->parent->name, "Bone") + std::string("_GeomAdjust");
+  }
+  else {
+    name = get_fbx_name(node->name, "Bone");
+  }
+  EditBone *bone = ED_armature_ebone_add(arm, name.c_str());
   this->mapping.node_to_name.add(node, bone->name);
   this->mapping.node_is_blender_bone.add(node);
   this->mapping.bone_to_armature.add(node, arm_obj);

source/blender/io/fbx/importer/fbx_import_mesh.cc

@@ -524,7 +524,15 @@ void import_meshes(Main &bmain,
 
     /* Create objects that use this mesh. */
     for (const ufbx_node *node : fmesh->instances) {
-      Object *obj = BKE_object_add_only_object(&bmain, OB_MESH, get_fbx_name(node->name));
+      std::string name;
+      if (node->is_geometry_transform_helper) {
+        /* Name geometry transform adjustment helpers with parent name and _GeomAdjust suffix. */
+        name = get_fbx_name(node->parent->name) + std::string("_GeomAdjust");
+      }
+      else {
+        name = get_fbx_name(node->name);
+      }
+      Object *obj = BKE_object_add_only_object(&bmain, OB_MESH, name.c_str());
       obj->data = mesh_main;
       if (!node->visible) {
         obj->visibility_flag |= OB_HIDE_VIEWPORT;

tests/files/io_tests/fbx/reference/ufbx_max_geometry_transform_instances_77b.txt

@@ -29,25 +29,41 @@
     - (1.000, 1.000)
     - (0.000, 1.000)
 
-==== Objects: 4
-- Obj 'Box001' MESH data:'Mesh'
+==== Objects: 8
+- Obj 'Box001' EMPTY
   - pos 0.000, 0.000, 0.254
   - rot 0.000, 0.000, 0.000 (XYZ)
   - scl 0.025, 0.025, 0.025
   - props: int:MaxHandle=1
-- Obj 'Box002' MESH data:'Mesh' par:'Box001'
+- Obj 'Box001_GeomAdjust' MESH data:'Mesh' par:'Box001'
+  - pos 40.000, 0.000, -10.000
+  - rot 0.000, 0.000, 0.000 (XYZ)
+  - scl 1.000, 1.000, 1.000
+- Obj 'Box002' EMPTY par:'Box001'
   - pos 0.000, 0.000, 10.000
   - rot 0.000, 0.000, 0.524 (XYZ)
   - scl 1.000, 1.000, 1.000
   - props: int:MaxHandle=5
-- Obj 'Box003' MESH data:'Mesh' par:'Box002'
+- Obj 'Box002_GeomAdjust' MESH data:'Mesh' par:'Box002'
+  - pos 20.000, 34.641, -20.000
+  - rot 0.000, 0.000, -0.524 (XYZ)
+  - scl 1.000, 1.000, 1.500
+- Obj 'Box003' EMPTY par:'Box002'
   - pos 0.000, 0.000, 20.000
   - rot 0.000, 0.000, 0.524 (XYZ)
   - scl 1.000, 1.000, 1.000
   - props: int:MaxHandle=6
-- Obj 'Box004' MESH data:'Mesh' par:'Box003'
+- Obj 'Box003_GeomAdjust' MESH data:'Mesh' par:'Box003'
+  - pos -20.000, 34.641, -40.000
+  - rot 0.000, 0.000, -1.047 (XYZ)
+  - scl 1.000, 1.000, 2.000
+- Obj 'Box004' EMPTY par:'Box003'
   - pos 0.000, 0.000, 10.000
   - rot 0.000, 0.000, 0.524 (XYZ)
   - scl 1.000, 1.000, 1.000
   - props: int:MaxHandle=7
+- Obj 'Box004_GeomAdjust' MESH data:'Mesh' par:'Box004'
+  - pos -40.000, 0.000, -50.000
+  - rot 0.000, 0.000, 0.000 (XYZ)
+  - scl 1.000, 1.000, 2.500