glTF importer: Fix import SK when there is no target on all primitives

io_scene_gltf2/__init__.py

@@ -4,7 +4,7 @@
 bl_info = {
     'name': 'glTF 2.0 format',
     'author': 'Julien Duroure, Scurest, Norbert Nopper, Urs Hanselmann, Moritz Becher, Benjamin Schmithüsen, Jim Eckerlein, and many external contributors',
-    "version": (3, 4, 29),
+    "version": (3, 4, 30),
     'blender': (3, 3, 0),
     'location': 'File > Import-Export',
     'description': 'Import-Export as glTF 2.0',

io_scene_gltf2/blender/imp/gltf2_blender_gltf.py

@@ -158,22 +158,36 @@ class BlenderGlTF():
             mesh.shapekey_names = []
             used_names = set(['Basis']) #Be sure to not use 'Basis' name at import, this is a reserved name
 
-            # Some invalid glTF files has empty primitive tab
-            if len(mesh.primitives) > 0:
-                for sk, target in enumerate(mesh.primitives[0].targets or []):
-                    if 'POSITION' not in target:
+            # Look for primitive with morph targets
+            for prim in (mesh.primitives or []):
+                if not prim.targets:
+                    continue
+
+                for sk, _ in enumerate(prim.targets):
+                    # Skip shape key for target that doesn't morph POSITION
+                    morphs_position = any(
+                        (prim.targets and 'POSITION' in prim.targets[sk])
+                        for prim in mesh.primitives
+                    )
+                    if not morphs_position:
                         mesh.shapekey_names.append(None)
                         continue
 
-                    # Check if glTF file has some extras with targetNames. Otherwise
-                    # use the name of the POSITION accessor on the first primitive.
                     shapekey_name = None
-                    if mesh.extras is not None:
-                        if 'targetNames' in mesh.extras and sk < len(mesh.extras['targetNames']):
-                            shapekey_name = mesh.extras['targetNames'][sk]
+
+                    # Try to use name from extras.targetNames
+                    try:
+                        shapekey_name = str(mesh.extras['targetNames'][sk])
+                    except Exception:
+                        pass
+
+                    # Try to get name from first primitive's POSITION accessor
                     if shapekey_name is None:
-                        if gltf.data.accessors[target['POSITION']].name is not None:
-                            shapekey_name = gltf.data.accessors[target['POSITION']].name
+                        try:
+                            shapekey_name = gltf.data.accessors[mesh.primitives[0].targets[sk]['POSITION']].name
+                        except Exception:
+                            pass
+
                     if shapekey_name is None:
                         shapekey_name = "target_" + str(sk)
 
@@ -182,6 +196,8 @@ class BlenderGlTF():
 
                     mesh.shapekey_names.append(shapekey_name)
 
+                break
+
         # Manage KHR_materials_variants
         BlenderGlTF.manage_material_variants(gltf)
 

io_scene_gltf2/blender/imp/gltf2_blender_mesh.py

@@ -98,11 +98,7 @@ def do_primitives(gltf, mesh_idx, skin_idx, mesh, ob):
         while i < COLOR_MAX and ('COLOR_%d' % i) in prim.attributes: i += 1
         num_cols = max(i, num_cols)
 
-    num_shapekeys = 0
-    if len(pymesh.primitives) > 0: # Empty primitive tab is not allowed, but some invalid files...
-        for morph_i, _ in enumerate(pymesh.primitives[0].targets or []):
-            if pymesh.shapekey_names[morph_i] is not None:
-                num_shapekeys += 1
+    num_shapekeys = sum(sk_name is not None for sk_name in pymesh.shapekey_names)
 
     # -------------
     # We'll process all the primitives gathering arrays to feed into the
@@ -190,12 +186,17 @@ def do_primitives(gltf, mesh_idx, skin_idx, mesh, ob):
             vert_joints[i] = np.concatenate((vert_joints[i], js))
             vert_weights[i] = np.concatenate((vert_weights[i], ws))
 
-        for morph_i, target in enumerate(prim.targets or []):
-            if pymesh.shapekey_names[morph_i] is None:
+        sk_i = 0
+        for sk, sk_name in enumerate(pymesh.shapekey_names):
+            if sk_name is None:
                 continue
-            morph_vs = BinaryData.decode_accessor(gltf, target['POSITION'], cache=True)
-            morph_vs = morph_vs[unique_indices]
-            sk_vert_locs[morph_i] = np.concatenate((sk_vert_locs[morph_i], morph_vs))
+            if prim.targets and 'POSITION' in prim.targets[sk]:
+                morph_vs = BinaryData.decode_accessor(gltf, prim.targets[sk]['POSITION'], cache=True)
+                morph_vs = morph_vs[unique_indices]
+            else:
+                morph_vs = np.zeros((len(unique_indices), 3), dtype=np.float32)
+            sk_vert_locs[sk_i] = np.concatenate((sk_vert_locs[sk_i], morph_vs))
+            sk_i += 1
 
         # inv_indices are the indices into the verts just for this prim;
         # calculate indices into the overall verts array