glTF exporter: Manage emission strength in materials

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, 4, 24),
+    "version": (1, 4, 25),
     'blender': (2, 90, 0),
     'location': 'File > Import-Export',
     'description': 'Import-Export as glTF 2.0',

io_scene_gltf2/blender/exp/gltf2_blender_gather_materials.py

@@ -109,13 +109,36 @@ def __gather_emissive_factor(blender_material, export_settings):
     if emissive_socket is None:
         emissive_socket = gltf2_blender_get.get_socket_old(blender_material, "EmissiveFactor")
     if isinstance(emissive_socket, bpy.types.NodeSocket):
-        fac = gltf2_blender_get.get_factor_from_socket(emissive_socket, kind='RGB')
-        if fac is None and emissive_socket.is_linked:
+        factor = gltf2_blender_get.get_factor_from_socket(emissive_socket, kind='RGB')
+
+        if factor is None and emissive_socket.is_linked:
             # In glTF, the default emissiveFactor is all zeros, so if an emission texture is connected,
             # we have to manually set it to all ones.
-            fac = [1.0, 1.0, 1.0]
-        if fac == [0, 0, 0]: fac = None
-        return fac
+            factor = [1.0, 1.0, 1.0]
+
+        if factor is None: factor = [0.0, 0.0, 0.0]
+
+        # Handle Emission Strength
+        strength_socket = None
+        if emissive_socket.node.type == 'EMISSION':
+            strength_socket = emissive_socket.node.inputs['Strength']
+        elif 'Emission Strength' in emissive_socket.node.inputs:
+            strength_socket = emissive_socket.node.inputs['Emission Strength']
+        strength = (
+            gltf2_blender_get.get_const_from_socket(strength_socket, kind='VALUE')
+            if strength_socket is not None
+            else None
+        )
+        if strength is not None:
+            factor = [f * strength for f in factor]
+
+        # Clamp to range [0,1]
+        factor = [min(1.0, f) for f in factor]
+
+        if factor == [0, 0, 0]: factor = None
+
+        return factor
+
     return None
 
 

io_scene_gltf2/blender/exp/gltf2_blender_get.py

@@ -227,7 +227,7 @@ def get_factor_from_socket(socket, kind):
     from a MULTIPLY node just before the socket.
     kind is either 'RGB' or 'VALUE'.
     """
-    fac = __get_const_from_socket(socket, kind)
+    fac = get_const_from_socket(socket, kind)
     if fac is not None:
         return fac
 
@@ -237,19 +237,19 @@ def get_factor_from_socket(socket, kind):
         if kind == 'RGB':
             if node.type == 'MIX_RGB' and node.blend_type == 'MULTIPLY':
                 # TODO: handle factor in inputs[0]?
-                x1 = __get_const_from_socket(node.inputs[1], kind)
-                x2 = __get_const_from_socket(node.inputs[2], kind)
+                x1 = get_const_from_socket(node.inputs[1], kind)
+                x2 = get_const_from_socket(node.inputs[2], kind)
         if kind == 'VALUE':
             if node.type == 'MATH' and node.operation == 'MULTIPLY':
-                x1 = __get_const_from_socket(node.inputs[0], kind)
-                x2 = __get_const_from_socket(node.inputs[1], kind)
+                x1 = get_const_from_socket(node.inputs[0], kind)
+                x2 = get_const_from_socket(node.inputs[1], kind)
         if x1 is not None and x2 is None: return x1
         if x2 is not None and x1 is None: return x2
 
     return None
 
 
-def __get_const_from_socket(socket, kind):
+def get_const_from_socket(socket, kind):
     if not socket.is_linked:
         if kind == 'RGB':
             if socket.type != 'RGBA': return None