+def check_group(node_tree, group, func):
+ output = group.node_tree.nodes["Group Output"]
+ from_node, _ = get_linked_node_and_socket(group.node_tree, output.inputs[0])
+ if from_node:
+ from_node, _ = func(group.node_tree, from_node)
+ if from_node and from_node.type=='GROUP_INPUT':
+ return get_linked_node_and_socket(node_tree, group.inputs[0])
+ return (None, None)
+
+def check_invert_green(node_tree, node):
+ if node.type=='GROUP':
+ return check_group(node_tree, node, check_invert_green)
+ elif node.type!='COMBRGB':
+ return (None, None)
+
+ green, g_sock = get_linked_node_and_socket(node_tree, node.inputs["G"])
+ if not green or green.type!='MATH' or green.operation!='SUBTRACT':
+ return (None, None)
+ green, g_sock = get_linked_node_and_socket(node_tree, green.inputs[1])
+
+ red, r_sock = get_linked_node_and_socket(node_tree, node.inputs["R"])
+ blue, b_sock = get_linked_node_and_socket(node_tree, node.inputs["B"])
+ if not red or red.type!='SEPRGB' or blue!=red or green!=red:
+ return (None, None)
+
+ return get_linked_node_and_socket(node_tree, red.inputs["Image"])
+