From 3a5aaa9b9999a0eada72076ba5b5bacc653e4528 Mon Sep 17 00:00:00 2001
From: Julien Duroure <julien.duroure@gmail.com>
Date: Sat, 5 Sep 2020 15:33:18 +0200
Subject: glTF exporter: materials: export factors from MULTIPLY nodes

---
 io_scene_gltf2/blender/exp/gltf2_blender_get.py | 64 +++++++++++++++++++++++++
 1 file changed, 64 insertions(+)

(limited to 'io_scene_gltf2/blender/exp/gltf2_blender_get.py')

diff --git a/io_scene_gltf2/blender/exp/gltf2_blender_get.py b/io_scene_gltf2/blender/exp/gltf2_blender_get.py
index 4f66aa6a..27f4ae18 100755
--- a/io_scene_gltf2/blender/exp/gltf2_blender_get.py
+++ b/io_scene_gltf2/blender/exp/gltf2_blender_get.py
@@ -218,3 +218,67 @@ def get_node(data_path):
         return None
 
     return node_name[:(index)]
+
+
+def get_factor_from_socket(socket, kind):
+    """
+    For baseColorFactor, metallicFactor, etc.
+    Get a constant value from a socket, or a constant value
+    from a MULTIPLY node just before the socket.
+    kind is either 'RGB' or 'VALUE'.
+    """
+    fac = __get_const_from_socket(socket, kind)
+    if fac is not None:
+        return fac
+
+    node = __previous_node(socket)
+    if node is not None:
+        x1, x2 = None, None
+        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)
+        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)
+        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):
+    if not socket.is_linked:
+        if kind == 'RGB':
+            if socket.type != 'RGBA': return None
+            return list(socket.default_value)[:3]
+        if kind == 'VALUE':
+            if socket.type != 'VALUE': return None
+            return socket.default_value
+
+    # Handle connection to a constant RGB/Value node
+    prev_node = __previous_node(socket)
+    if prev_node is not None:
+        if kind == 'RGB' and prev_node.type == 'RGB':
+            return list(prev_node.outputs[0].default_value)[:3]
+        if kind == 'VALUE' and prev_node.type == 'VALUE':
+            return prev_node.outputs[0].default_value
+
+    return None
+
+
+def __previous_node(socket):
+    while True:
+        if not socket.is_linked:
+            return None
+
+        node = socket.links[0].from_node
+
+        # Skip over reroute nodes
+        if node.type == 'REROUTE':
+            socket = node.inputs[0]
+            continue
+
+        return node
-- 
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