glTF importer: Fix bug importing some morph targsts with no POSITION

Do not create a shapekey in that case, ignoring animation on this morph target too

io_scene_gltf2/blender/imp/gltf2_blender_animation_node.py

@@ -140,12 +140,13 @@ class BlenderNodeAnim():
 
                 for idx, key in enumerate(keys):
                     for sk in range(nb_targets):
-                        obj.data.shape_keys.key_blocks[sk + 1].value = values[idx * nb_targets + sk][0]
-                        obj.data.shape_keys.key_blocks[sk + 1].keyframe_insert(
-                            "value",
-                            frame=key[0] * fps,
-                            group='ShapeKeys'
-                        )
+                        if gltf.shapekeys[sk] is not None: # Do not animate shapekeys not created
+                            obj.data.shape_keys.key_blocks[gltf.shapekeys[sk]].value = values[idx * nb_targets + sk][0]
+                            obj.data.shape_keys.key_blocks[gltf.shapekeys[sk]].keyframe_insert(
+                                "value",
+                                frame=key[0] * fps,
+                                group='ShapeKeys'
+                            )
 
         if action.name not in gltf.current_animation_names.keys():
             gltf.current_animation_names[name] = action.name

io_scene_gltf2/blender/imp/gltf2_blender_gltf.py

@@ -86,6 +86,10 @@ class BlenderGlTF():
         # Init is to False, and will be set to True during creation
         gltf.animation_object = False
 
+        # Store shapekeys equivalent between target & shapekey index
+        # For example when no POSITION on target
+        gltf.shapekeys = {}
+
         # Blender material
         if gltf.data.materials:
             for material in gltf.data.materials:

io_scene_gltf2/blender/imp/gltf2_blender_mesh.py

@@ -108,9 +108,16 @@ class BlenderMesh():
         if max_shape_to_create > 0:
             obj.shape_key_add(name="Basis")
 
+        current_shapekey_index = 0
         for i in range(max_shape_to_create):
 
+            # Check if this target has POSITION
+            if 'POSITION' not in prim.targets[i].keys():
+                gltf.shapekeys[i] = None
+                continue
+
             obj.shape_key_add(name="target_" + str(i))
+            current_shapekey_index += 1
 
             offset_idx = 0
             for prim in pymesh.primitives:
@@ -122,7 +129,8 @@ class BlenderMesh():
                 bm = bmesh.new()
                 bm.from_mesh(mesh)
 
-                shape_layer = bm.verts.layers.shape[i + 1]
+                shape_layer = bm.verts.layers.shape[current_shapekey_index]
+                gltf.shapekeys[i] = current_shapekey_index
 
                 pos = BinaryData.get_data_from_accessor(gltf, prim.targets[i]['POSITION'])
 
@@ -145,9 +153,11 @@ class BlenderMesh():
         if pymesh.weights is not None:
             for i in range(max_shape_to_create):
                 if i < len(pymesh.weights):
-                    obj.data.shape_keys.key_blocks[i + 1].value = pymesh.weights[i]
+                    if gltf.shapekeys[i] is None: # No default value if shapekeys was not created
+                        continue
+                    obj.data.shape_keys.key_blocks[gltf.shapekeys[i]].value = pymesh.weights[i]
                     if gltf.data.accessors[pymesh.primitives[0].targets[i]['POSITION']].name is not None:
-                        obj.data.shape_keys.key_blocks[i + 1].name = \
+                        obj.data.shape_keys.key_blocks[gltf.shapekeys[i]].name = \
                             gltf.data.accessors[pymesh.primitives[0].targets[i]['POSITION']].name
 
         # Apply vertex color.