Support user extensions

The extension plugin should receive a dictionary with the properties

addons/io_scene_gltf2/__init__.py

@@ -67,6 +67,7 @@ def reload_package_recursive(current_dir, module_dict):
 #  Functions / Classes.
 #
 
+extension_panel_unregister_functors = []
 
 class ExportGLTF2_Base:
     # TODO: refactor to avoid boilerplate
@@ -326,6 +327,7 @@ def __init__(self):
     def invoke(self, context, event):
         settings = context.scene.get(self.scene_key)
         self.will_save_settings = False
+        self.has_active_extenions = False
         if settings:
             try:
                 for (k, v) in settings.items():
@@ -336,6 +338,18 @@ def invoke(self, context, event):
                 self.report({"ERROR"}, "Loading export settings failed. Removed corrupted settings")
                 del context.scene[self.scene_key]
 
+        if bpy.app.version < (2,80,0):
+            pass
+        else:
+            import sys
+            for addon_name in bpy.context.preferences.addons.keys():
+                try:
+                    if hasattr(sys.modules[addon_name], 'glTF2ExportUserExtension'):
+                        extension_panel_unregister_functors.append(sys.modules[addon_name].register_panel())
+                        self.has_active_extenions = True
+                except Exception:
+                    pass
+
         return ExportHelper.invoke(self, context, event)
 
     def save_settings(self, context):
@@ -429,6 +443,18 @@ def execute(self, context):
         export_settings['gltf_binaryfilename'] = os.path.splitext(os.path.basename(
             bpy.path.ensure_ext(self.filepath,self.filename_ext)))[0] + '.bin'
 
+        user_extensions = []
+
+        if bpy.app.version < (2,80,0):
+            pass
+        else:
+            import sys
+            for addon_name in bpy.context.preferences.addons.keys():
+                if hasattr(sys.modules[addon_name], 'glTF2ExportUserExtension'):
+                    extension_ctor = sys.modules[addon_name].glTF2ExportUserExtension
+                    user_extensions.append(extension_ctor())
+        export_settings['gltf_user_extensions'] = user_extensions
+
         return gltf2_blender_export.save(context, export_settings)
     if bpy.app.version < (2, 80, 0):
         def draw(self, context):
@@ -788,6 +814,25 @@ def draw(self, context):
         layout.active = operator.export_skins
         layout.prop(operator, 'export_all_influences')
 
+class GLTF_PT_export_user_extensions(bpy.types.Panel):
+    bl_space_type = 'FILE_BROWSER'
+    bl_region_type = 'TOOL_PROPS'
+    bl_label = "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 == "EXPORT_SCENE_OT_gltf" and operator.has_active_extenions
+
+    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"""
@@ -919,6 +964,7 @@ def menu_func_import(self, context):
         GLTF_PT_export_animation_export,
         GLTF_PT_export_animation_shapekeys,
         GLTF_PT_export_animation_skinning,
+        GLTF_PT_export_user_extensions,
         ImportGLTF2
     )
 
@@ -940,6 +986,9 @@ def register():
 def unregister():
     for c in classes:
         bpy.utils.unregister_class(c)
+    for f in extension_panel_unregister_functors:
+        f()
+
     # bpy.utils.unregister_module(__name__)
 
     # remove from the export / import menu

addons/io_scene_gltf2/blender/exp/gltf2_blender_gather_animation_channel_target.py

@@ -20,6 +20,7 @@
 from io_scene_gltf2.blender.exp import gltf2_blender_gather_nodes
 from io_scene_gltf2.blender.exp import gltf2_blender_gather_joints
 from io_scene_gltf2.blender.exp import gltf2_blender_gather_skins
+from io_scene_gltf2.io.exp.gltf2_io_user_extensions import export_user_extensions
 
 @cached
 def gather_animation_channel_target(channels: typing.Tuple[bpy.types.FCurve],
@@ -29,13 +30,23 @@ def gather_animation_channel_target(channels: typing.Tuple[bpy.types.FCurve],
                                     export_settings
                                     ) -> gltf2_io.AnimationChannelTarget:
 
-        return gltf2_io.AnimationChannelTarget(
+        animation_channel_target = gltf2_io.AnimationChannelTarget(
             extensions=__gather_extensions(channels, blender_object, export_settings, bake_bone),
             extras=__gather_extras(channels, blender_object, export_settings, bake_bone),
             node=__gather_node(channels, blender_object, export_settings, bake_bone),
             path=__gather_path(channels, blender_object, export_settings, bake_bone, bake_channel)
         )
 
+        export_user_extensions('gather_animation_channel_target_hook', 
+                               export_settings, 
+                               animation_channel_target, 
+                               channels, 
+                               blender_object, 
+                               bake_bone, 
+                               bake_channel)
+
+        return animation_channel_target
+
 def __gather_extensions(channels: typing.Tuple[bpy.types.FCurve],
                         blender_object: bpy.types.Object,
                         export_settings,

addons/io_scene_gltf2/blender/exp/gltf2_blender_gather_animation_channels.py

@@ -23,6 +23,7 @@
 from io_scene_gltf2.blender.exp import gltf2_blender_gather_animation_channel_target
 from io_scene_gltf2.blender.exp import gltf2_blender_get
 from io_scene_gltf2.blender.exp import gltf2_blender_gather_skins
+from io_scene_gltf2.io.exp.gltf2_io_user_extensions import export_user_extensions
 
 
 @cached
@@ -136,13 +137,26 @@ def __gather_animation_channel(channels: typing.Tuple[bpy.types.FCurve],
     if not __filter_animation_channel(channels, blender_object, export_settings):
         return None
 
-    return gltf2_io.AnimationChannel(
+    animation_channel = gltf2_io.AnimationChannel(
         extensions=__gather_extensions(channels, blender_object, export_settings, bake_bone),
         extras=__gather_extras(channels, blender_object, export_settings, bake_bone),
         sampler=__gather_sampler(channels, blender_object, export_settings, bake_bone, bake_channel, bake_range_start, bake_range_end, action_name),
         target=__gather_target(channels, blender_object, export_settings, bake_bone, bake_channel)
     )
 
+    export_user_extensions('gather_animation_channel_hook', 
+                           export_settings, 
+                           animation_channel, 
+                           channels, 
+                           blender_object, 
+                           bake_bone, 
+                           bake_channel, 
+                           bake_range_start, 
+                           bake_range_end, 
+                           action_name)
+
+    return animation_channel
+
 
 def __filter_animation_channel(channels: typing.Tuple[bpy.types.FCurve],
                                blender_object: bpy.types.Object,

addons/io_scene_gltf2/blender/exp/gltf2_blender_gather_animation_samplers.py

@@ -27,6 +27,7 @@
 from io_scene_gltf2.io.com import gltf2_io_constants
 from io_scene_gltf2.io.exp import gltf2_io_binary_data
 from . import gltf2_blender_export_keys
+from io_scene_gltf2.io.exp.gltf2_io_user_extensions import export_user_extensions
 
 
 @cached
@@ -55,7 +56,7 @@ def gather_animation_sampler(channels: typing.Tuple[bpy.types.FCurve],
                                                  export_settings)
 
 
-    return gltf2_io.AnimationSampler(
+    sampler = gltf2_io.AnimationSampler(
         extensions=__gather_extensions(channels, blender_object_if_armature, export_settings, bake_bone, bake_channel),
         extras=__gather_extras(channels, blender_object_if_armature, export_settings, bake_bone, bake_channel),
         input=__gather_input(channels, blender_object_if_armature, non_keyed_values,
@@ -72,6 +73,19 @@ def gather_animation_sampler(channels: typing.Tuple[bpy.types.FCurve],
                                export_settings)
     )
 
+    export_user_extensions('gather_animation_sampler_hook', 
+                            export_settings, 
+                            sampler, 
+                            channels, 
+                            blender_object, 
+                            bake_bone, 
+                            bake_channel, 
+                            bake_range_start, 
+                            bake_range_end, 
+                            action_name)
+
+    return sampler
+
 def __gather_non_keyed_values(channels: typing.Tuple[bpy.types.FCurve],
                               blender_object: bpy.types.Object,
                               blender_object_if_armature: typing.Optional[bpy.types.Object],

addons/io_scene_gltf2/blender/exp/gltf2_blender_gather_animations.py

@@ -19,6 +19,7 @@
 from io_scene_gltf2.blender.exp import gltf2_blender_gather_animation_channels
 from io_scene_gltf2.io.com.gltf2_io_debug import print_console
 from ..com.gltf2_blender_extras import generate_extras
+from io_scene_gltf2.io.exp.gltf2_io_user_extensions import export_user_extensions
 
 
 def gather_animations(blender_object: bpy.types.Object,
@@ -108,6 +109,8 @@ def __gather_animation(blender_action: bpy.types.Action,
     if not animation.channels:
         return None
 
+    export_user_extensions('gather_animation_hook', export_settings, animation, blender_action, blender_object)
+
     return animation
 
 

addons/io_scene_gltf2/blender/exp/gltf2_blender_gather_cameras.py

@@ -16,6 +16,7 @@
 from io_scene_gltf2.blender.exp.gltf2_blender_gather_cache import cached
 from ..com.gltf2_blender_extras import generate_extras
 from io_scene_gltf2.io.com import gltf2_io
+from io_scene_gltf2.io.exp.gltf2_io_user_extensions import export_user_extensions
 
 import bpy
 import math
@@ -26,7 +27,7 @@ def gather_camera(blender_camera, export_settings):
     if not __filter_camera(blender_camera, export_settings):
         return None
 
-    return gltf2_io.Camera(
+    camera = gltf2_io.Camera(
         extensions=__gather_extensions(blender_camera, export_settings),
         extras=__gather_extras(blender_camera, export_settings),
         name=__gather_name(blender_camera, export_settings),
@@ -35,6 +36,10 @@ def gather_camera(blender_camera, export_settings):
         type=__gather_type(blender_camera, export_settings)
     )
 
+    export_user_extensions('gather_camera_hook', export_settings, camera, blender_camera)
+
+    return camera
+
 
 def __filter_camera(blender_camera, export_settings):
     return bool(__gather_type(blender_camera, export_settings))

addons/io_scene_gltf2/blender/exp/gltf2_blender_gather_image.py

@@ -26,6 +26,7 @@
 from io_scene_gltf2.io.com import gltf2_io_debug
 from io_scene_gltf2.blender.exp import gltf2_blender_image
 from io_scene_gltf2.blender.exp.gltf2_blender_gather_cache import cached
+from io_scene_gltf2.io.exp.gltf2_io_user_extensions import export_user_extensions
 
 
 @cached
@@ -47,7 +48,7 @@ def gather_image(
     uri = __gather_uri(image_data, mime_type, name, export_settings)
     buffer_view = __gather_buffer_view(image_data, mime_type, name, export_settings)
 
-    return __make_image(
+    image = __make_image(
         buffer_view,
         __gather_extensions(blender_shader_sockets_or_texture_slots, export_settings),
         __gather_extras(blender_shader_sockets_or_texture_slots, export_settings),
@@ -57,6 +58,10 @@ def gather_image(
         export_settings
     )
 
+    export_user_extensions('gather_image_hook', export_settings, image, blender_shader_sockets_or_texture_slots)
+
+    return image
+
 @cached
 def __make_image(buffer_view, extensions, extras, mime_type, name, uri, export_settings):
     return gltf2_io.Image(

addons/io_scene_gltf2/blender/exp/gltf2_blender_gather_material_normal_texture_info_class.py

@@ -21,6 +21,7 @@
 from io_scene_gltf2.blender.exp import gltf2_blender_export_keys
 from io_scene_gltf2.blender.exp import gltf2_blender_get
 from io_scene_gltf2.io.com.gltf2_io_extensions import Extension
+from io_scene_gltf2.io.exp.gltf2_io_user_extensions import export_user_extensions
 
 
 @cached
@@ -41,6 +42,11 @@ def gather_material_normal_texture_info_class(blender_shader_sockets_or_texture_
     if texture_info.index is None:
         return None
 
+    export_user_extensions('gather_material_normal_texture_info_class_hook', 
+                           export_settings, 
+                           texture_info, 
+                           blender_shader_sockets_or_texture_slots)
+
     return texture_info
 
 

addons/io_scene_gltf2/blender/exp/gltf2_blender_gather_material_occlusion_texture_info_class.py

@@ -20,6 +20,7 @@
 from io_scene_gltf2.blender.exp import gltf2_blender_search_node_tree
 from io_scene_gltf2.blender.exp import gltf2_blender_get
 from io_scene_gltf2.io.com.gltf2_io_extensions import Extension
+from io_scene_gltf2.io.exp.gltf2_io_user_extensions import export_user_extensions
 
 
 @cached
@@ -40,6 +41,11 @@ def gather_material_occlusion_texture_info_class(blender_shader_sockets_or_textu
     if texture_info.index is None:
         return None
 
+    export_user_extensions('gather_material_occlusion_texture_info_class_hook', 
+                           export_settings, 
+                           texture_info, 
+                           blender_shader_sockets_or_texture_slots)
+
     return texture_info
 
 

addons/io_scene_gltf2/blender/exp/gltf2_blender_gather_materials.py

@@ -25,6 +25,7 @@
 from io_scene_gltf2.blender.exp import gltf2_blender_gather_materials_pbr_metallic_roughness
 from ..com.gltf2_blender_extras import generate_extras
 from io_scene_gltf2.blender.exp import gltf2_blender_get
+from io_scene_gltf2.io.exp.gltf2_io_user_extensions import export_user_extensions
 
 
 @cached
@@ -55,6 +56,8 @@ def gather_material(blender_material, mesh_double_sided, export_settings):
         pbr_metallic_roughness=__gather_pbr_metallic_roughness(blender_material, orm_texture, export_settings)
     )
 
+    export_user_extensions('gather_material_hook', export_settings, material, blender_material)
+
     return material
     # material = blender_primitive['material']
     #

addons/io_scene_gltf2/blender/exp/gltf2_blender_gather_materials_pbr_metallic_roughness.py

@@ -20,6 +20,7 @@
 from io_scene_gltf2.blender.exp import gltf2_blender_get
 from io_scene_gltf2.blender.exp.gltf2_blender_gather_cache import cached
 from io_scene_gltf2.io.com.gltf2_io_debug import print_console
+from io_scene_gltf2.io.exp.gltf2_io_user_extensions import export_user_extensions
 
 
 @cached
@@ -37,6 +38,8 @@ def gather_material_pbr_metallic_roughness(blender_material, orm_texture, export
         roughness_factor=__gather_roughness_factor(blender_material, export_settings)
     )
 
+    export_user_extensions('gather_material_pbr_metallic_roughness_hook', export_settings, material, blender_material, orm_texture)
+
     return material
 
 

addons/io_scene_gltf2/blender/exp/gltf2_blender_gather_mesh.py

@@ -20,6 +20,7 @@
 from io_scene_gltf2.blender.exp import gltf2_blender_gather_primitives
 from ..com.gltf2_blender_extras import generate_extras
 from io_scene_gltf2.io.com.gltf2_io_debug import print_console
+from io_scene_gltf2.io.exp.gltf2_io_user_extensions import export_user_extensions
 
 
 @cached
@@ -45,6 +46,17 @@ def gather_mesh(blender_mesh: bpy.types.Mesh,
     if len(mesh.primitives) == 0:
         print_console("WARNING", "Mesh '{}' has no primitives and will be omitted.".format(mesh.name))
         return None
+
+    export_user_extensions('gather_mesh_hook', 
+                           export_settings, 
+                           mesh, 
+                           blender_mesh, 
+                           blender_object, 
+                           vertex_groups, 
+                           modifiers, 
+                           skip_filter, 
+                           material_names)
+
     return mesh
 
 

addons/io_scene_gltf2/blender/exp/gltf2_blender_gather_nodes.py

@@ -28,6 +28,7 @@
 from ..com.gltf2_blender_extras import generate_extras
 from io_scene_gltf2.io.com import gltf2_io
 from io_scene_gltf2.io.com import gltf2_io_extensions
+from io_scene_gltf2.io.exp.gltf2_io_user_extensions import export_user_extensions 
 
 
 def gather_node(blender_object, blender_scene, export_settings):
@@ -86,6 +87,8 @@ def __gather_node(blender_object, blender_scene, export_settings):
             node.children.append(correction_node)
         node.camera = None
 
+    export_user_extensions('gather_node_hook', export_settings, node, blender_object)
+
     return node