glTF importer/exporter: Manage some official Khronos Extensions about Materials

    KHR_materials_ior
    KHR_materials_sheen
    KHR_materials_specular
    KHR_materials_transmission
    KHR_materials_variants
    KHR_materials_emissive_strength
    KHR_materials_volume

Documentation update is still in progress

1 files changed, 47 insertions, 0 deletions

diff --git a/io_scene_gltf2/blender/exp/gltf2_blender_gather_materials_transmission.py b/io_scene_gltf2/blender/exp/gltf2_blender_gather_materials_transmission.py
new file mode 100644
index 00000000..fdc5d8c7
--- /dev/null
+++ b/io_scene_gltf2/blender/exp/gltf2_blender_gather_materials_transmission.py
@@ -0,0 +1,47 @@
+# SPDX-License-Identifier: Apache-2.0
+# Copyright 2018-2022 The glTF-Blender-IO authors.
+
+import bpy
+from io_scene_gltf2.io.com.gltf2_io_extensions import Extension
+from io_scene_gltf2.blender.exp import gltf2_blender_get
+from io_scene_gltf2.blender.exp import gltf2_blender_gather_texture_info
+
+def export_transmission(blender_material, export_settings):
+    transmission_enabled = False
+    has_transmission_texture = False
+
+    transmission_extension = {}
+    transmission_slots = ()
+
+    transmission_socket = gltf2_blender_get.get_socket(blender_material, 'Transmission')
+
+    if isinstance(transmission_socket, bpy.types.NodeSocket) and not transmission_socket.is_linked:
+        transmission_extension['transmissionFactor'] = transmission_socket.default_value
+        transmission_enabled = transmission_extension['transmissionFactor'] > 0
+    elif gltf2_blender_get.has_image_node_from_socket(transmission_socket):
+        fac = gltf2_blender_get.get_factor_from_socket(transmission_socket, kind='VALUE')
+        transmission_extension['transmissionFactor'] = fac if fac is not None else 1.0
+        has_transmission_texture = True
+        transmission_enabled = True
+
+    if not transmission_enabled:
+        return None, None
+
+    # Pack transmission channel (R).
+    if has_transmission_texture:
+        transmission_slots = (transmission_socket,)
+
+    use_actives_uvmaps = []
+
+    if len(transmission_slots) > 0:
+        combined_texture, use_active_uvmap, _ = gltf2_blender_gather_texture_info.gather_texture_info(
+            transmission_socket,
+            transmission_slots,
+            export_settings,
+        )
+        if has_transmission_texture:
+            transmission_extension['transmissionTexture'] = combined_texture
+        if use_active_uvmap:
+            use_actives_uvmaps.append("transmissionTexture")
+
+    return Extension('KHR_materials_transmission', transmission_extension, False), use_actives_uvmaps
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