From 1ebae998eb54c3f33900dc76de3b34c2d5252e58 Mon Sep 17 00:00:00 2001
From: Mikko Rasa <tdb@tdb.fi>
Date: Sat, 5 Mar 2022 11:00:58 +0200
Subject: [PATCH] Make texture channel handling in the Blender exporter more
 flexible

Any channel can now be inverted (though the shader graph inspection does
not detect this yet), so a separate invert_green channel is no longer
needed.
---
 blender/io_mspgl/export_material.py |  2 +-
 blender/io_mspgl/export_texture.py  | 31 +++++++++++++++++------------
 blender/io_mspgl/material.py        | 20 +++++++++----------
 3 files changed, 29 insertions(+), 24 deletions(-)

diff --git a/blender/io_mspgl/export_material.py b/blender/io_mspgl/export_material.py
index a109ed24..ffdae1cc 100644
--- a/blender/io_mspgl/export_material.py
+++ b/blender/io_mspgl/export_material.py
@@ -79,7 +79,7 @@ class MaterialExporter:
 
 			tex_name = p.texture.image.name+".tex2d"
 			if tex_name not in resources:
-				resources[tex_name] = texture_export.export_texture(p.texture, p.tex_usage, invert_green=p.invert_green)
+				resources[tex_name] = texture_export.export_texture(p.texture, p.tex_channels)
 
 			samp_name = sampler_export.get_sampler_name(p.texture)
 			if samp_name not in resources:
diff --git a/blender/io_mspgl/export_texture.py b/blender/io_mspgl/export_texture.py
index c304fd7e..eb6fa223 100644
--- a/blender/io_mspgl/export_texture.py
+++ b/blender/io_mspgl/export_texture.py
@@ -11,18 +11,21 @@ def pixels_to_rgb(pixels):
 		yield int(pixels[i+1]*255)
 		yield int(pixels[i+2]*255)
 
-def pixels_to_rgb_invert_green(pixels):
+def pixels_to_rgb_invert(pixels, mask):
 	for i in range(0, len(pixels), 4):
-		yield int(pixels[i]*255)
-		yield 255-int(pixels[i+1]*255)
-		yield int(pixels[i+2]*255)
+		r = int(pixels[i]*255)
+		yield 255-r if mask&1 else r
+		g = int(pixels[i+1]*255)
+		yield 255-g if mask&2 else g
+		b = int(pixels[i+2]*255)
+		yield 255-b if mask&4 else b
 
 def pixels_to_gray(pixels):
 	for i in range(0, len(pixels), 4):
 		yield int((pixels[i]+pixels[i+1]+pixels[i+2])*255/3)
 
 class TextureExporter:
-	def export_texture(self, tex_node, usage='RGB', *, invert_green=False):
+	def export_texture(self, tex_node, channels=['R', 'G', 'B']):
 		image = tex_node.image
 		from .datafile import RawData, Resource, Statement, Token
 		tex_res = Resource(image.name+".tex", "texture")
@@ -33,20 +36,22 @@ class TextureExporter:
 			tex_res.statements.append(Statement("generate_mipmap", True))
 
 		colorspace = image.colorspace_settings.name
-		if usage=='GRAY' and colorspace=='sRGB':
+		if len(channels)==1 and colorspace=='sRGB':
 			raise Exception("Unsupported configuration on texture {}: Grayscale with sRGB".format(image.name))
 
+		invert_mask = sum(1<<i for i, c in enumerate(channels) if c[0]=='~')
+
 		from .util import basename
 		fn = basename(image.filepath)
-		if not invert_green and fn:
+		if not invert_mask and fn:
 			if not tex_node.use_mipmap:
 				tex_res.statements.append(Statement("mipmap_levels", 1))
 			srgb = "_srgb" if colorspace=='sRGB' else ""
 			tex_res.statements.append(Statement("external_image"+srgb, fn))
 		else:
-			if usage=='RGBA':
+			if len(channels)==4:
 				fmt = 'SRGB8_ALPHA8' if colorspace=='sRGB' else 'RGBA8'
-			elif usage=='GRAY':
+			elif len(channels)==1:
 				fmt = 'LUMINANCE8'
 			else:
 				fmt = 'SRGB8' if colorspace=='sRGB' else 'RGB8'
@@ -55,12 +60,12 @@ class TextureExporter:
 
 			pixels = tuple(image.pixels)
 			texdata = ""
-			if usage=='RGBA':
+			if len(channels)==4:
 				texdata = pixels_to_rgba(pixels)
-			elif usage=='GRAY':
+			elif len(channels)==1:
 				texdata = pixels_to_gray(pixels)
-			elif invert_green:
-				texdata = pixels_to_rgb_invert_green(pixels)
+			elif invert_mask:
+				texdata = pixels_to_rgb_invert(pixels, invert_mask)
 			else:
 				texdata = pixels_to_rgb(pixels)
 
diff --git a/blender/io_mspgl/material.py b/blender/io_mspgl/material.py
index 87e9479b..b30a2ef5 100644
--- a/blender/io_mspgl/material.py
+++ b/blender/io_mspgl/material.py
@@ -89,8 +89,7 @@ class MaterialProperty:
 		self.tex_keyword = tex_keyword
 		self.value = value
 		self.texture = None
-		self.tex_usage = None
-		self.invert_green = False
+		self.tex_channels = None
 
 	def set_from_input(self, node_tree, input_socket, alpha_socket=None):
 		if self.keyword:
@@ -108,16 +107,17 @@ class MaterialProperty:
 			from_node, _ = get_linked_node_and_socket(node_tree, input_socket)
 			alpha_from = None
 			if from_node:
-				usage = None
+				channels = None
 				if from_node.type=='NORMAL_MAP':
 					from_node, _ = get_linked_node_and_socket(node_tree, from_node.inputs["Color"])
 					invert, _ = check_invert_green(node_tree, from_node)
+					channels = ['R', 'G', 'B']
 					if invert:
 						from_node = invert
-						self.invert_green = True
-					usage = 'RGB'
+						channels[1] = '~G';
 				elif from_node.type=='RGBTOBW':
 					from_node, _ = get_linked_node_and_socket(node_tree, from_node.inputs["Color"])
+					channels = ['Y']
 
 				if alpha_socket:
 					alpha_from, _ = get_linked_node_and_socket(node_tree, alpha_socket)
@@ -126,14 +126,14 @@ class MaterialProperty:
 
 				if from_node.type=='TEX_IMAGE':
 					self.texture = from_node
-					if usage:
-						self.tex_usage = usage
+					if channels:
+						self.tex_channels = channels
 					elif alpha_from:
-						self.tex_usage = 'RGBA'
+						self.tex_channels = ['R', 'G', 'B', 'A']
 					elif type(self.value)==tuple:
-						self.tex_usage = 'RGB'
+						self.tex_channels = ['R', 'G', 'B']
 					else:
-						self.tex_usage = 'GRAY'
+						self.tex_channels = ['Y']
 				else:
 					raise Exception("Unsupported property input node type "+from_node.type)
 
-- 
2.43.0