glTF exporter: new feature: KHR_materials_clearcoat export

3 files changed, 66 insertions, 2 deletions

diff --git a/io_scene_gltf2/__init__.py b/io_scene_gltf2/__init__.py
index 49f6f470..c42cbc75 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, Norbert Nopper, Urs Hanselmann, Moritz Becher, Benjamin Schmithüsen, Jim Eckerlein, and many external contributors',
-    "version": (1, 2, 38),
+    "version": (1, 2, 39),
     'blender': (2, 82, 7),
     'location': 'File > Import-Export',
     'description': 'Import-Export as glTF 2.0',
diff --git a/io_scene_gltf2/blender/exp/gltf2_blender_gather_image.py b/io_scene_gltf2/blender/exp/gltf2_blender_gather_image.py
index c389ba19..d1579803 100755
--- a/io_scene_gltf2/blender/exp/gltf2_blender_gather_image.py
+++ b/io_scene_gltf2/blender/exp/gltf2_blender_gather_image.py
@@ -174,6 +174,10 @@ def __get_image_data(sockets_or_slots, export_settings) -> ExportImage:
                 dst_chan = Channel.R
             elif socket.name == 'Alpha' and len(sockets_or_slots) > 1 and sockets_or_slots[1] is not None:
                 dst_chan = Channel.A
+            elif socket.name == 'Clearcoat':
+                dst_chan = Channel.R
+            elif socket.name == 'Clearcoat Roughness':
+                dst_chan = Channel.G
 
             if dst_chan is not None:
                 composed_image.fill_image(result.shader_node.image, dst_chan, src_chan)
diff --git a/io_scene_gltf2/blender/exp/gltf2_blender_gather_materials.py b/io_scene_gltf2/blender/exp/gltf2_blender_gather_materials.py
index 35028e5b..42c71150 100755
--- a/io_scene_gltf2/blender/exp/gltf2_blender_gather_materials.py
+++ b/io_scene_gltf2/blender/exp/gltf2_blender_gather_materials.py
@@ -129,10 +129,18 @@ def __gather_emissive_texture(blender_material, export_settings):
 def __gather_extensions(blender_material, export_settings):
     extensions = {}
 
+    # KHR_materials_unlit
+
     if gltf2_blender_get.get_socket_or_texture_slot(blender_material, "Background") is not None:
         extensions["KHR_materials_unlit"] = Extension("KHR_materials_unlit", {}, False)
 
-    # TODO specular glossiness extension
+    # KHR_materials_clearcoat
+
+    clearcoat_extension = __gather_clearcoat_extension(blender_material, export_settings)
+    if clearcoat_extension:
+        extensions["KHR_materials_clearcoat"] = clearcoat_extension
+
+    # TODO KHR_materials_pbrSpecularGlossiness
 
     return extensions if extensions else None
 
@@ -217,3 +225,55 @@ def __has_image_node_from_socket(socket):
     if not result:
         return False
     return True
+
+def __gather_clearcoat_extension(blender_material, export_settings):
+    clearcoat_enabled = False
+    has_clearcoat_texture = False
+    has_clearcoat_roughness_texture = False
+
+    clearcoat_extension = {}
+    clearcoat_roughness_slots = ()
+
+    clearcoat_socket = gltf2_blender_get.get_socket_or_texture_slot(blender_material, 'Clearcoat')
+    clearcoat_roughness_socket = gltf2_blender_get.get_socket_or_texture_slot(blender_material, 'Clearcoat Roughness')
+    clearcoat_normal_socket = gltf2_blender_get.get_socket_or_texture_slot(blender_material, 'Clearcoat Normal')
+
+    if isinstance(clearcoat_socket, bpy.types.NodeSocket) and not clearcoat_socket.is_linked:
+        clearcoat_extension['clearcoatFactor'] = clearcoat_socket.default_value
+        clearcoat_enabled = clearcoat_extension['clearcoatFactor'] > 0
+    elif __has_image_node_from_socket(clearcoat_socket):
+        clearcoat_extension['clearcoatFactor'] = 1
+        has_clearcoat_texture = True
+        clearcoat_enabled = True
+
+    if not clearcoat_enabled:
+        return None
+
+    if isinstance(clearcoat_roughness_socket, bpy.types.NodeSocket) and not clearcoat_roughness_socket.is_linked:
+        clearcoat_extension['clearcoatRoughnessFactor'] = clearcoat_roughness_socket.default_value
+    elif __has_image_node_from_socket(clearcoat_roughness_socket):
+        clearcoat_extension['clearcoatRoughnessFactor'] = 1
+        has_clearcoat_roughness_texture = True
+
+    # Pack clearcoat (R) and clearcoatRoughness (G) channels.
+    if has_clearcoat_texture and has_clearcoat_roughness_texture:
+        clearcoat_roughness_slots = (clearcoat_socket, clearcoat_roughness_socket,)
+    elif has_clearcoat_texture:
+        clearcoat_roughness_slots = (clearcoat_socket,)
+    elif has_clearcoat_roughness_texture:
+        clearcoat_roughness_slots = (clearcoat_roughness_socket,)
+
+    if len(clearcoat_roughness_slots) > 0:
+        combined_texture = gltf2_blender_gather_texture_info.gather_texture_info(clearcoat_roughness_slots, export_settings)
+        if has_clearcoat_texture:
+            clearcoat_extension['clearcoatTexture'] = combined_texture
+        if has_clearcoat_roughness_texture:
+            clearcoat_extension['clearcoatRoughnessTexture'] = combined_texture
+
+    if __has_image_node_from_socket(clearcoat_normal_socket):
+        clearcoat_extension['clearcoatNormalTexture'] = gltf2_blender_gather_material_normal_texture_info_class.gather_material_normal_texture_info_class(
+            (clearcoat_normal_socket,),
+            export_settings
+        )
+
+    return Extension('KHR_materials_clearcoat', clearcoat_extension, False)