glTF: implement occlusion strength (importer & exporter)

2 files changed, 31 insertions, 1 deletions

diff --git a/io_scene_gltf2/blender/exp/gltf2_blender_gather_texture_info.py b/io_scene_gltf2/blender/exp/gltf2_blender_gather_texture_info.py
index 59cd5614..30975a3f 100755
--- a/io_scene_gltf2/blender/exp/gltf2_blender_gather_texture_info.py
+++ b/io_scene_gltf2/blender/exp/gltf2_blender_gather_texture_info.py
@@ -123,6 +123,19 @@ def __gather_normal_scale(primary_socket, export_settings):
 
 # MaterialOcclusionTextureInfo only
 def __gather_occlusion_strength(primary_socket, export_settings):
+    # Look for a MixRGB node that mixes with pure white in front of
+    # primary_socket. The mix factor gives the occlusion strength.
+    node = gltf2_blender_get.previous_node(primary_socket)
+    if node and node.type == 'MIX_RGB' and node.blend_type == 'MIX':
+        fac = gltf2_blender_get.get_const_from_socket(node.inputs['Fac'], kind='VALUE')
+        col1 = gltf2_blender_get.get_const_from_socket(node.inputs['Color1'], kind='RGB')
+        col2 = gltf2_blender_get.get_const_from_socket(node.inputs['Color2'], kind='RGB')
+        if fac is not None:
+            if col1 == [1, 1, 1] and col2 is None:
+                return fac
+            if col1 is None and col2 == [1, 1, 1]:
+                return 1.0 - fac  # reversed for reversed inputs
+
     return None
 
 
diff --git a/io_scene_gltf2/blender/imp/gltf2_blender_pbrMetallicRoughness.py b/io_scene_gltf2/blender/imp/gltf2_blender_pbrMetallicRoughness.py
index 4bc584b0..21400bc0 100755
--- a/io_scene_gltf2/blender/imp/gltf2_blender_pbrMetallicRoughness.py
+++ b/io_scene_gltf2/blender/imp/gltf2_blender_pbrMetallicRoughness.py
@@ -433,13 +433,30 @@ def normal(mh: MaterialHelper, location, normal_socket):
     )
 
 
-# [Texture] => [Separate R] =>
+# [Texture] => [Separate R] => [Mix Strength] =>
 def occlusion(mh: MaterialHelper, location, occlusion_socket):
     x, y = location
 
     if mh.pymat.occlusion_texture is None:
         return
 
+    strength = mh.pymat.occlusion_texture.strength
+    if strength is None: strength = 1.0
+    if strength != 1.0:
+        # Mix with white
+        node = mh.node_tree.nodes.new('ShaderNodeMixRGB')
+        node.label = 'Occlusion Strength'
+        node.location = x - 140, y
+        node.blend_type = 'MIX'
+        # Outputs
+        mh.node_tree.links.new(occlusion_socket, node.outputs[0])
+        # Inputs
+        node.inputs['Fac'].default_value = strength
+        node.inputs['Color1'].default_value = [1, 1, 1, 1]
+        occlusion_socket = node.inputs['Color2']
+
+        x -= 200
+
     # Separate RGB
     node = mh.node_tree.nodes.new('ShaderNodeSeparateRGB')
     node.location = x - 150, y - 75