From d89b65cc91a63544168b5330ba1a288f5c826e15 Mon Sep 17 00:00:00 2001
From: Bastien Montagne <montagne29@wanadoo.fr>
Date: Thu, 17 Oct 2019 11:35:38 +0200
Subject: Node shader wrapper: use 'Non-Color' profile for BW textures inputs.
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All the single-value texture inputs of Principled BSDF node should use
non-color colorspace profile, not sRGB one (issue raised in
https://blender.stackexchange.com/questions/155617, thanks).

That also revealed another issue - since those color space settings are
stored at the image level itself, not the node one, we need to
duplicate those image data-blocks when we use same picture for e.g. base
color (sRGB) and specular (non-color) inputs...

For now using a basic mechanism for that, might generate several extra,
uneeded copies of the image ID, but that’s better than breaking custom
settings and such.

Note that while this will modify the behavior of the impporters using
that node wrapper, no change should be needed in IO add-ons themselves.
---
 release/scripts/modules/bpy_extras/node_shader_utils.py | 16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)

(limited to 'release/scripts/modules')

diff --git a/release/scripts/modules/bpy_extras/node_shader_utils.py b/release/scripts/modules/bpy_extras/node_shader_utils.py
index 720d1d8af5a..ce5edde5adf 100644
--- a/release/scripts/modules/bpy_extras/node_shader_utils.py
+++ b/release/scripts/modules/bpy_extras/node_shader_utils.py
@@ -336,6 +336,7 @@ class PrincipledBSDFWrapper(ShaderWrapper):
             self, self.node_principled_bsdf,
             self.node_principled_bsdf.inputs["Specular"],
             grid_row_diff=0,
+            colorspace_name='Non-Color',
         )
 
     specular_texture = property(specular_texture_get)
@@ -367,6 +368,7 @@ class PrincipledBSDFWrapper(ShaderWrapper):
             self, self.node_principled_bsdf,
             self.node_principled_bsdf.inputs["Roughness"],
             grid_row_diff=0,
+            colorspace_name='Non-Color',
         )
 
     roughness_texture = property(roughness_texture_get)
@@ -398,6 +400,7 @@ class PrincipledBSDFWrapper(ShaderWrapper):
             self, self.node_principled_bsdf,
             self.node_principled_bsdf.inputs["Metallic"],
             grid_row_diff=0,
+            colorspace_name='Non-Color',
         )
 
     metallic_texture = property(metallic_texture_get)
@@ -428,6 +431,7 @@ class PrincipledBSDFWrapper(ShaderWrapper):
             self, self.node_principled_bsdf,
             self.node_principled_bsdf.inputs["IOR"],
             grid_row_diff=-1,
+            colorspace_name='Non-Color',
         )
 
     ior_texture = property(ior_texture_get)
@@ -455,6 +459,7 @@ class PrincipledBSDFWrapper(ShaderWrapper):
             self, self.node_principled_bsdf,
             self.node_principled_bsdf.inputs["Transmission"],
             grid_row_diff=-1,
+            colorspace_name='Non-Color',
         )
 
     transmission_texture = property(transmission_texture_get)
@@ -482,6 +487,7 @@ class PrincipledBSDFWrapper(ShaderWrapper):
             self, self.node_principled_bsdf,
             self.node_principled_bsdf.inputs["Alpha"],
             grid_row_diff=-1,
+            colorspace_name='Non-Color',
         )
 
     alpha_texture = property(alpha_texture_get)
@@ -568,6 +574,7 @@ class ShaderImageTextureWrapper():
         "grid_row_diff",
         "use_alpha",
         "colorspace_is_data",
+        "colorspace_name",
         *NODES_LIST,
     )
 
@@ -580,7 +587,7 @@ class ShaderImageTextureWrapper():
         return instance
 
     def __init__(self, owner_shader: ShaderWrapper, node_dst, socket_dst, grid_row_diff=0,
-                 use_alpha=False, colorspace_is_data=...):
+                 use_alpha=False, colorspace_is_data=..., colorspace_name=...):
         self.owner_shader = owner_shader
         self.is_readonly = owner_shader.is_readonly
         self.node_dst = node_dst
@@ -588,6 +595,7 @@ class ShaderImageTextureWrapper():
         self.grid_row_diff = grid_row_diff
         self.use_alpha = use_alpha
         self.colorspace_is_data = colorspace_is_data
+        self.colorspace_name = colorspace_name
 
         self._node_image = ...
         self._node_mapping = ...
@@ -685,7 +693,13 @@ class ShaderImageTextureWrapper():
     @_set_check
     def image_set(self, image):
         if self.colorspace_is_data is not ...:
+            if image.colorspace_settings.is_data != self.colorspace_is_data and image.users >= 1:
+                image = image.copy()
             image.colorspace_settings.is_data = self.colorspace_is_data
+        if self.colorspace_name is not ...:
+            if image.colorspace_settings.is_data != self.colorspace_is_data and image.users >= 1:
+                image = image.copy()
+            image.colorspace_settings.name = self.colorspace_name
         self.node_image.image = image
 
     image = property(image_get, image_set)
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