From 02748ad414e4d209189a1fbf99ddc370cc39b418 Mon Sep 17 00:00:00 2001
From: Mikko Rasa <tdb@tdb.fi>
Date: Sat, 5 Mar 2022 19:56:34 +0200
Subject: [PATCH] Handle arbitrary channel inversions in material inputs.

---
 blender/io_mspgl/material.py | 33 +++++++++++++++++++--------------
 1 file changed, 19 insertions(+), 14 deletions(-)

diff --git a/blender/io_mspgl/material.py b/blender/io_mspgl/material.py
index db68d0ba..84226130 100644
--- a/blender/io_mspgl/material.py
+++ b/blender/io_mspgl/material.py
@@ -20,7 +20,7 @@ class PropertyNode:
 		checks = [self.check_group,
 			self.check_gray,
 			self.check_normal,
-			self.check_invert_green,
+			self.check_invert_channels,
 			self.check_additive_blend,
 			self.check_texture]
 		for c in checks:
@@ -60,24 +60,29 @@ class PropertyNode:
 			self.type = 'NORMAL'
 			return self.set_input_from_linked(self.node.inputs["Color"])
 
-	def check_invert_green(self):
+	def check_invert_channels(self):
 		if self.node.type!='COMBRGB':
 			return
 
 		from .util import get_linked_node_and_socket
 
-		green, _ = get_linked_node_and_socket(self.node_tree, self.node.inputs["G"])
-		if not green or green.type!='MATH' or green.operation!='SUBTRACT':
-			return
-		green, _ = get_linked_node_and_socket(self.node_tree, green.inputs[1])
+		separate = None
+		invert_channels = ""
+		for c in ("R", "G", "B"):
+			from_node, _ = get_linked_node_and_socket(self.node_tree, self.node.inputs[c])
+			if from_node.type=='MATH' and from_node.operation=='SUBTRACT' and not from_node.inputs[0].is_linked and from_node.inputs[0].default_value==1.0:
+				invert_channels += c
+				from_node, _ = get_linked_node_and_socket(self.node_tree, from_node.inputs[1])
 
-		red, _ = get_linked_node_and_socket(self.node_tree, self.node.inputs["R"])
-		blue, _ = get_linked_node_and_socket(self.node_tree, self.node.inputs["B"])
-		if not red or red.type!='SEPRGB' or blue!=red or green!=red:
-			return
+			if from_node.type=='SEPRGB' and (separate is None or from_node==separate):
+				separate = from_node
+			else:
+				return
+
+		self.type = 'INVERT'
+		self.data = invert_channels
 
-		self.type = 'INVERT_GREEN'
-		return self.set_input_from_linked(red.inputs["Image"])
+		return self.set_input_from_linked(separate.inputs["Image"])
 
 	def check_additive_blend(self):
 		if self.node.type=='ADD_SHADER':
@@ -152,8 +157,8 @@ class MaterialProperty:
 						channels = ['R', 'G', 'B']
 					elif n.type=='GRAY':
 						channels = ['Y']
-					elif n.type=='INVERT_GREEN':
-						channels[1] = '~G'
+					elif n.type=='INVERT':
+						channels = ['~'+c if c in n.data else c for c in channels]
 					elif n.type=='TEXTURE':
 						self.texture = n.node
 					n = n.input
-- 
2.43.0