glTF importer: Implement a user extension system

13 files changed, 154 insertions, 15 deletions

diff --git a/io_scene_gltf2/__init__.py b/io_scene_gltf2/__init__.py
index 97ef843b..1a97bee8 100755
--- a/io_scene_gltf2/__init__.py
+++ b/io_scene_gltf2/__init__.py
@@ -15,7 +15,7 @@
 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": (1, 8, 12),
+    "version": (1, 8, 13),
     'blender': (3, 1, 0),
     'location': 'File > Import-Export',
     'description': 'Import-Export as glTF 2.0',
@@ -67,7 +67,8 @@ from bpy_extras.io_utils import ImportHelper, ExportHelper
 #  Functions / Classes.
 #
 
-extension_panel_unregister_functors = []
+exporter_extension_panel_unregister_functors = []
+importer_extension_panel_unregister_functors = []
 
 
 def ensure_filepath_matches_export_format(filepath, export_format):
@@ -479,11 +480,11 @@ class ExportGLTF2_Base:
         for addon_name in preferences.addons.keys():
             try:
                 if hasattr(sys.modules[addon_name], 'glTF2ExportUserExtension') or hasattr(sys.modules[addon_name], 'glTF2ExportUserExtensions'):
-                    extension_panel_unregister_functors.append(sys.modules[addon_name].register_panel())
+                    exporter_extension_panel_unregister_functors.append(sys.modules[addon_name].register_panel())
             except Exception:
                 pass
 
-        self.has_active_extensions = len(extension_panel_unregister_functors) > 0
+        self.has_active_exporter_extensions = len(exporter_extension_panel_unregister_functors) > 0
         return ExportHelper.invoke(self, context, event)
 
     def save_settings(self, context):
@@ -945,7 +946,7 @@ class GLTF_PT_export_animation_skinning(bpy.types.Panel):
 class GLTF_PT_export_user_extensions(bpy.types.Panel):
     bl_space_type = 'FILE_BROWSER'
     bl_region_type = 'TOOL_PROPS'
-    bl_label = "Extensions"
+    bl_label = "Exporter Extensions"
     bl_parent_id = "FILE_PT_operator"
     bl_options = {'DEFAULT_CLOSED'}
 
@@ -954,13 +955,30 @@ class GLTF_PT_export_user_extensions(bpy.types.Panel):
         sfile = context.space_data
         operator = sfile.active_operator
 
-        return operator.bl_idname == "EXPORT_SCENE_OT_gltf" and operator.has_active_extensions
+        return operator.bl_idname == "EXPORT_SCENE_OT_gltf" and operator.has_active_exporter_extensions
 
     def draw(self, context):
         layout = self.layout
         layout.use_property_split = True
         layout.use_property_decorate = False  # No animation.
 
+class GLTF_PT_import_user_extensions(bpy.types.Panel):
+    bl_space_type = 'FILE_BROWSER'
+    bl_region_type = 'TOOL_PROPS'
+    bl_label = "Importer Extensions"
+    bl_parent_id = "FILE_PT_operator"
+    bl_options = {'DEFAULT_CLOSED'}
+
+    @classmethod
+    def poll(cls, context):
+        sfile = context.space_data
+        operator = sfile.active_operator
+        return operator.bl_idname == "IMPORT_SCENE_OT_gltf" and operator.has_active_importer_extensions
+
+    def draw(self, context):
+        layout = self.layout
+        layout.use_property_split = True
+        layout.use_property_decorate = False  # No animation.
 
 class ExportGLTF2(bpy.types.Operator, ExportGLTF2_Base, ExportHelper):
     """Export scene as glTF 2.0 file"""
@@ -1060,6 +1078,19 @@ class ImportGLTF2(Operator, ImportHelper):
         layout.prop(self, 'guess_original_bind_pose')
         layout.prop(self, 'bone_heuristic')
 
+    def invoke(self, context, event):
+        import sys
+        preferences = bpy.context.preferences
+        for addon_name in preferences.addons.keys():
+            try:
+                if hasattr(sys.modules[addon_name], 'glTF2ImportUserExtension') or hasattr(sys.modules[addon_name], 'glTF2ImportUserExtensions'):
+                    importer_extension_panel_unregister_functors.append(sys.modules[addon_name].register_panel())
+            except Exception:
+                pass
+
+        self.has_active_importer_extensions = len(importer_extension_panel_unregister_functors) > 0
+        return ImportHelper.invoke(self, context, event)
+
     def execute(self, context):
         return self.import_gltf2(context)
 
@@ -1069,6 +1100,20 @@ class ImportGLTF2(Operator, ImportHelper):
         self.set_debug_log()
         import_settings = self.as_keywords()
 
+        user_extensions = []
+
+        import sys
+        preferences = bpy.context.preferences
+        for addon_name in preferences.addons.keys():
+            try:
+                module = sys.modules[addon_name]
+            except Exception:
+                continue
+            if hasattr(module, 'glTF2ImportUserExtension'):
+                extension_ctor = module.glTF2ImportUserExtension
+                user_extensions.append(extension_ctor())
+        import_settings['import_user_extensions'] = user_extensions
+
         if self.files:
             # Multiple file import
             ret = {'CANCELLED'}
@@ -1137,7 +1182,8 @@ classes = (
     GLTF_PT_export_animation_shapekeys,
     GLTF_PT_export_animation_skinning,
     GLTF_PT_export_user_extensions,
-    ImportGLTF2
+    ImportGLTF2,
+    GLTF_PT_import_user_extensions
 )
 
 
@@ -1154,9 +1200,13 @@ def register():
 def unregister():
     for c in classes:
         bpy.utils.unregister_class(c)
-    for f in extension_panel_unregister_functors:
+    for f in exporter_extension_panel_unregister_functors:
+        f()
+    exporter_extension_panel_unregister_functors.clear()
+
+    for f in importer_extension_panel_unregister_functors:
         f()
-    extension_panel_unregister_functors.clear()
+    importer_extension_panel_unregister_functors.clear()
 
     # bpy.utils.unregister_module(__name__)
 
diff --git a/io_scene_gltf2/blender/imp/gltf2_blender_animation_node.py b/io_scene_gltf2/blender/imp/gltf2_blender_animation_node.py
index 642515aa..03f8592c 100755
--- a/io_scene_gltf2/blender/imp/gltf2_blender_animation_node.py
+++ b/io_scene_gltf2/blender/imp/gltf2_blender_animation_node.py
@@ -18,6 +18,7 @@ from mathutils import Vector
 from ...io.imp.gltf2_io_binary import BinaryData
 from .gltf2_blender_animation_utils import make_fcurve
 from .gltf2_blender_vnode import VNode
+from io_scene_gltf2.io.imp.gltf2_io_user_extensions import import_user_extensions
 
 
 class BlenderNodeAnim():
@@ -46,6 +47,8 @@ class BlenderNodeAnim():
         vnode = gltf.vnodes[node_idx]
         path = channel.target.path
 
+        import_user_extensions('gather_import_animation_channel_before_hook', gltf, animation, vnode, path, channel)
+
         action = BlenderNodeAnim.get_or_create_action(gltf, node_idx, animation.track_name)
 
         keys = BinaryData.get_data_from_accessor(gltf, animation.samplers[channel.sampler].input)
@@ -152,6 +155,8 @@ class BlenderNodeAnim():
                 interpolation=animation.samplers[channel.sampler].interpolation,
             )
 
+        import_user_extensions('gather_import_animation_channel_after_hook', gltf, animation, vnode, path, channel, action)
+
     @staticmethod
     def get_or_create_action(gltf, node_idx, anim_name):
         vnode = gltf.vnodes[node_idx]
diff --git a/io_scene_gltf2/blender/imp/gltf2_blender_animation_weight.py b/io_scene_gltf2/blender/imp/gltf2_blender_animation_weight.py
index 19723ed9..3b864d6b 100644
--- a/io_scene_gltf2/blender/imp/gltf2_blender_animation_weight.py
+++ b/io_scene_gltf2/blender/imp/gltf2_blender_animation_weight.py
@@ -16,6 +16,7 @@ import bpy
 
 from ...io.imp.gltf2_io_binary import BinaryData
 from .gltf2_blender_animation_utils import make_fcurve
+from io_scene_gltf2.io.imp.gltf2_io_user_extensions import import_user_extensions
 
 
 class BlenderWeightAnim():
@@ -29,6 +30,9 @@ class BlenderWeightAnim():
         vnode = gltf.vnodes[vnode_id]
 
         node_idx = vnode.mesh_node_idx
+
+        import_user_extensions('gather_import_animation_weight_before_hook', gltf, vnode, gltf.data.animations[anim_idx])
+
         if node_idx is None:
             return
 
@@ -90,3 +94,5 @@ class BlenderWeightAnim():
                 max_weight = max(coords[1:2])
                 if min_weight < kb.slider_min: kb.slider_min = min_weight
                 if max_weight > kb.slider_max: kb.slider_max = max_weight
+
+        import_user_extensions('gather_import_animation_weight_after_hook', gltf, vnode, animation)
diff --git a/io_scene_gltf2/blender/imp/gltf2_blender_camera.py b/io_scene_gltf2/blender/imp/gltf2_blender_camera.py
index cc73a690..e5f6e3d1 100755
--- a/io_scene_gltf2/blender/imp/gltf2_blender_camera.py
+++ b/io_scene_gltf2/blender/imp/gltf2_blender_camera.py
@@ -14,6 +14,7 @@
 
 import bpy
 from ..com.gltf2_blender_extras import set_extras
+from io_scene_gltf2.io.imp.gltf2_io_user_extensions import import_user_extensions
 
 
 class BlenderCamera():
@@ -22,10 +23,12 @@ class BlenderCamera():
         raise RuntimeError("%s should not be instantiated" % cls)
 
     @staticmethod
-    def create(gltf, camera_id):
+    def create(gltf, vnode, camera_id):
         """Camera creation."""
         pycamera = gltf.data.cameras[camera_id]
 
+        import_user_extensions('gather_import_camera_before_hook', gltf, vnode, pycamera)
+
         if not pycamera.name:
             pycamera.name = "Camera"
 
@@ -55,5 +58,4 @@ class BlenderCamera():
                 # Infinite projection
                 cam.clip_end = 1e12  # some big number
 
-
         return cam
diff --git a/io_scene_gltf2/blender/imp/gltf2_blender_image.py b/io_scene_gltf2/blender/imp/gltf2_blender_image.py
index 3acf1786..0df6dc0e 100755
--- a/io_scene_gltf2/blender/imp/gltf2_blender_image.py
+++ b/io_scene_gltf2/blender/imp/gltf2_blender_image.py
@@ -20,6 +20,7 @@ import urllib.parse
 import re
 
 from ...io.imp.gltf2_io_binary import BinaryData
+from io_scene_gltf2.io.imp.gltf2_io_user_extensions import import_user_extensions
 
 
 # Note that Image is not a glTF2.0 object
@@ -32,6 +33,9 @@ class BlenderImage():
     def create(gltf, img_idx):
         """Image creation."""
         img = gltf.data.images[img_idx]
+
+        import_user_extensions('gather_import_image_before_hook', gltf, img)
+
         img_name = img.name
 
         if img.blender_image_name is not None:
@@ -90,6 +94,8 @@ class BlenderImage():
                 if not is_placeholder and needs_pack:
                     blender_image.pack()
 
+        import_user_extensions('gather_import_image_after_hook', gltf, img, blender_image)
+
 def _placeholder_image(name, path):
     image = bpy.data.images.new(name, 128, 128)
     # allow the path to be resolved later
diff --git a/io_scene_gltf2/blender/imp/gltf2_blender_light.py b/io_scene_gltf2/blender/imp/gltf2_blender_light.py
index 71990eb3..9e6b8a96 100644
--- a/io_scene_gltf2/blender/imp/gltf2_blender_light.py
+++ b/io_scene_gltf2/blender/imp/gltf2_blender_light.py
@@ -16,6 +16,7 @@ import bpy
 from math import pi
 
 from ..com.gltf2_blender_extras import set_extras
+from io_scene_gltf2.io.imp.gltf2_io_user_extensions import import_user_extensions
 
 
 class BlenderLight():
@@ -24,9 +25,12 @@ class BlenderLight():
         raise RuntimeError("%s should not be instantiated" % cls)
 
     @staticmethod
-    def create(gltf, light_id):
+    def create(gltf, vnode, light_id):
         """Light creation."""
         pylight = gltf.data.extensions['KHR_lights_punctual']['lights'][light_id]
+
+        import_user_extensions('gather_import_light_before_hook', gltf, vnode, pylight)
+
         if pylight['type'] == "directional":
             light = BlenderLight.create_directional(gltf, light_id)
         elif pylight['type'] == "point":
diff --git a/io_scene_gltf2/blender/imp/gltf2_blender_material.py b/io_scene_gltf2/blender/imp/gltf2_blender_material.py
index 077f5af6..1a5be06f 100755
--- a/io_scene_gltf2/blender/imp/gltf2_blender_material.py
+++ b/io_scene_gltf2/blender/imp/gltf2_blender_material.py
@@ -18,6 +18,7 @@ from ..com.gltf2_blender_extras import set_extras
 from .gltf2_blender_pbrMetallicRoughness import MaterialHelper, pbr_metallic_roughness
 from .gltf2_blender_KHR_materials_pbrSpecularGlossiness import pbr_specular_glossiness
 from .gltf2_blender_KHR_materials_unlit import unlit
+from io_scene_gltf2.io.imp.gltf2_io_user_extensions import import_user_extensions
 
 
 class BlenderMaterial():
@@ -30,6 +31,8 @@ class BlenderMaterial():
         """Material creation."""
         pymaterial = gltf.data.materials[material_idx]
 
+        import_user_extensions('gather_import_material_before_hook', gltf, pymaterial, vertex_color)
+
         name = pymaterial.name
         if name is None:
             name = "Material_" + str(material_idx)
@@ -56,6 +59,8 @@ class BlenderMaterial():
         else:
             pbr_metallic_roughness(mh)
 
+        import_user_extensions('gather_import_material_after_hook', gltf, pymaterial, vertex_color, mat)
+
     @staticmethod
     def set_double_sided(pymaterial, mat):
         mat.use_backface_culling = (pymaterial.double_sided != True)
diff --git a/io_scene_gltf2/blender/imp/gltf2_blender_mesh.py b/io_scene_gltf2/blender/imp/gltf2_blender_mesh.py
index bbff340c..41dd4d03 100755
--- a/io_scene_gltf2/blender/imp/gltf2_blender_mesh.py
+++ b/io_scene_gltf2/blender/imp/gltf2_blender_mesh.py
@@ -21,6 +21,7 @@ from ..com.gltf2_blender_extras import set_extras
 from .gltf2_blender_material import BlenderMaterial
 from ...io.com.gltf2_io_debug import print_console
 from .gltf2_io_draco_compression_extension import decode_primitive
+from io_scene_gltf2.io.imp.gltf2_io_user_extensions import import_user_extensions
 
 
 class BlenderMesh():
@@ -41,6 +42,9 @@ COLOR_MAX = 8
 
 def create_mesh(gltf, mesh_idx, skin_idx):
     pymesh = gltf.data.meshes[mesh_idx]
+
+    import_user_extensions('gather_import_mesh_before_hook', gltf, pymesh)
+
     name = pymesh.name or 'Mesh_%d' % mesh_idx
     mesh = bpy.data.meshes.new(name)
 
@@ -56,6 +60,8 @@ def create_mesh(gltf, mesh_idx, skin_idx):
         if tmp_ob:
             bpy.data.objects.remove(tmp_ob)
 
+    import_user_extensions('gather_import_mesh_after_hook', gltf, pymesh, mesh)
+
     return mesh
 
 
diff --git a/io_scene_gltf2/blender/imp/gltf2_blender_node.py b/io_scene_gltf2/blender/imp/gltf2_blender_node.py
index ed164a1e..2fdbcfa5 100755
--- a/io_scene_gltf2/blender/imp/gltf2_blender_node.py
+++ b/io_scene_gltf2/blender/imp/gltf2_blender_node.py
@@ -19,6 +19,7 @@ from .gltf2_blender_mesh import BlenderMesh
 from .gltf2_blender_camera import BlenderCamera
 from .gltf2_blender_light import BlenderLight
 from .gltf2_blender_vnode import VNode
+from io_scene_gltf2.io.imp.gltf2_io_user_extensions import import_user_extensions
 
 class BlenderNode():
     """Blender Node."""
@@ -35,7 +36,10 @@ class BlenderNode():
             gltf.log.critical("Node %d of %d (id %s)", gltf.display_current_node, len(gltf.vnodes), vnode_id)
 
         if vnode.type == VNode.Object:
-            BlenderNode.create_object(gltf, vnode_id)
+            gltf_node = gltf.data.nodes[vnode_id] if isinstance(vnode_id, int) else None
+            import_user_extensions('gather_import_node_before_hook', gltf, vnode, gltf_node)
+            obj = BlenderNode.create_object(gltf, vnode_id)
+            import_user_extensions('gather_import_node_after_hook', gltf, vnode, gltf_node, obj)
             if vnode.is_arma:
                 BlenderNode.create_bones(gltf, vnode_id)
 
@@ -59,16 +63,22 @@ class BlenderNode():
 
         elif vnode.camera_node_idx is not None:
             pynode = gltf.data.nodes[vnode.camera_node_idx]
-            cam = BlenderCamera.create(gltf, pynode.camera)
+            cam = BlenderCamera.create(gltf, vnode, pynode.camera)
             name = vnode.name or cam.name
             obj = bpy.data.objects.new(name, cam)
 
+            # Since we create the actual Blender object after the create call, we call the hook here
+            import_user_extensions('gather_import_camera_after_hook', gltf, vnode, obj, cam)
+
         elif vnode.light_node_idx is not None:
             pynode = gltf.data.nodes[vnode.light_node_idx]
-            light = BlenderLight.create(gltf, pynode.extensions['KHR_lights_punctual']['light'])
+            light = BlenderLight.create(gltf, vnode, pynode.extensions['KHR_lights_punctual']['light'])
             name = vnode.name or light.name
             obj = bpy.data.objects.new(name, light)
 
+            # Since we create the actual Blender object after the create call, we call the hook here
+            import_user_extensions('gather_import_light_after_hook', gltf, vnode, obj, light)
+
         elif vnode.is_arma:
             armature = bpy.data.armatures.new(vnode.arma_name)
             name = vnode.name or armature.name
diff --git a/io_scene_gltf2/blender/imp/gltf2_blender_scene.py b/io_scene_gltf2/blender/imp/gltf2_blender_scene.py
index 05520228..57c53527 100755
--- a/io_scene_gltf2/blender/imp/gltf2_blender_scene.py
+++ b/io_scene_gltf2/blender/imp/gltf2_blender_scene.py
@@ -18,6 +18,7 @@ from .gltf2_blender_node import BlenderNode
 from .gltf2_blender_animation import BlenderAnimation
 from .gltf2_blender_vnode import VNode, compute_vnodes
 from ..com.gltf2_blender_extras import set_extras
+from io_scene_gltf2.io.imp.gltf2_io_user_extensions import import_user_extensions
 
 
 class BlenderScene():
@@ -36,6 +37,7 @@ class BlenderScene():
             scene.render.engine = "BLENDER_EEVEE"
 
         if gltf.data.scene is not None:
+            import_user_extensions('gather_import_scene_before_hook', gltf, gltf.data.scenes[gltf.data.scene], scene)
             pyscene = gltf.data.scenes[gltf.data.scene]
             set_extras(scene, pyscene.extras)
 
@@ -44,8 +46,14 @@ class BlenderScene():
         gltf.display_current_node = 0  # for debugging
         BlenderNode.create_vnode(gltf, 'root')
 
+        # User extensions before scene creation
+        import_user_extensions('gather_import_scene_after_nodes_hook', gltf, gltf.data.scenes[gltf.data.scene], scene)
+
+        # User extensions after scene creation
         BlenderScene.create_animations(gltf)
 
+        import_user_extensions('gather_import_scene_after_animation_hook', gltf, gltf.data.scenes[gltf.data.scene], scene)
+
         if bpy.context.mode != 'OBJECT':
             bpy.ops.object.mode_set(mode='OBJECT')
         BlenderScene.select_imported_objects(gltf)
diff --git a/io_scene_gltf2/blender/imp/gltf2_blender_texture.py b/io_scene_gltf2/blender/imp/gltf2_blender_texture.py
index ddeb5bfc..2a41c28e 100644
--- a/io_scene_gltf2/blender/imp/gltf2_blender_texture.py
+++ b/io_scene_gltf2/blender/imp/gltf2_blender_texture.py
@@ -18,6 +18,7 @@ from .gltf2_blender_image import BlenderImage
 from ..com.gltf2_blender_conversion import texture_transform_gltf_to_blender
 from io_scene_gltf2.io.com.gltf2_io import Sampler
 from io_scene_gltf2.io.com.gltf2_io_constants import TextureFilter, TextureWrap
+from io_scene_gltf2.io.imp.gltf2_io_user_extensions import import_user_extensions
 
 def texture(
     mh,
@@ -31,6 +32,9 @@ def texture(
     """Creates nodes for a TextureInfo and hooks up the color/alpha outputs."""
     x, y = location
     pytexture = mh.gltf.data.textures[tex_info.index]
+
+    import_user_extensions('gather_import_texture_before_hook', mh.gltf, pytexture, mh, tex_info, location, label, color_socket, alpha_socket, is_data)
+
     if pytexture.sampler is not None:
         pysampler = mh.gltf.data.samplers[pytexture.sampler]
     else:
@@ -166,6 +170,8 @@ def texture(
         # Outputs
         mh.node_tree.links.new(uv_socket, uv_map.outputs[0])
 
+    import_user_extensions('gather_import_texture_after_hook', mh.gltf, pytexture, mh.node_tree, mh, tex_info, location, label, color_socket, alpha_socket, is_data)
+
 def set_filtering(tex_img, pysampler):
     """Set the filtering/interpolation on an Image Texture from the glTf sampler."""
     minf = pysampler.min_filter
diff --git a/io_scene_gltf2/io/imp/gltf2_io_gltf.py b/io_scene_gltf2/io/imp/gltf2_io_gltf.py
index aa9bda38..407afccd 100755
--- a/io_scene_gltf2/io/imp/gltf2_io_gltf.py
+++ b/io_scene_gltf2/io/imp/gltf2_io_gltf.py
@@ -38,6 +38,7 @@ class glTFImporter():
         self.buffers = {}
         self.accessor_cache = {}
         self.decode_accessor_cache = {}
+        self.import_user_extensions = import_settings['import_user_extensions']
 
         if 'loglevel' not in self.import_settings.keys():
             self.import_settings['loglevel'] = logging.ERROR
@@ -57,6 +58,13 @@ class glTFImporter():
             'KHR_draco_mesh_compression'
         ]
 
+        # Add extensions required supported by custom import extensions
+        for import_extension in self.import_user_extensions:
+            if hasattr(import_extension, "extensions"):
+                for custom_extension in import_extension.extensions:
+                    if custom_extension.required:
+                        self.extensions_managed.append(custom_extension.name)
+
     @staticmethod
     def load_json(content):
         def bad_constant(val):
diff --git a/io_scene_gltf2/io/imp/gltf2_io_user_extensions.py b/io_scene_gltf2/io/imp/gltf2_io_user_extensions.py
new file mode 100644
index 00000000..0c439251
--- /dev/null
+++ b/io_scene_gltf2/io/imp/gltf2_io_user_extensions.py
@@ -0,0 +1,23 @@
+# Copyright 2018-2021 The glTF-Blender-IO authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+def import_user_extensions(hook_name, gltf_importer, *args):
+    for extension in gltf_importer.import_user_extensions:
+        hook = getattr(extension, hook_name, None)
+        if hook is not None:
+            try:
+                hook(*args, gltf_importer)
+            except Exception as e:
+                print(hook_name, "fails on", extension)
+                print(str(e))