From 1b795894be58dbf06b235aec436335227118bbfc Mon Sep 17 00:00:00 2001
From: Rasmus Bonnedal <rasmus.bonnedal@gmail.com>
Date: Sat, 22 Oct 2022 22:50:54 +0200
Subject: [PATCH] Fix implementation of screen node (#1111)

The parentheses were incorrectly placed in the implementation of the screen compositing node.

Changes from this:
    (mix * ((1 - (1 - fg)) * (1 - bg))) + ((1 - mix) * bg)

to this:
    (mix * ((1 - (1 - fg) * (1 - bg)))) + ((1 - mix) * bg)
---
 libraries/stdlib/genglsl/mx_screen.inline       | 2 +-
 libraries/stdlib/genmdl/stdlib_genmdl_impl.mtlx | 4 ++--
 libraries/stdlib/genosl/mx_screen.inline        | 2 +-
 source/MaterialXGenMdl/mdl/materialx/stdlib.mdl | 4 ++--
 4 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/libraries/stdlib/genglsl/mx_screen.inline b/libraries/stdlib/genglsl/mx_screen.inline
index cbfa5872e1..a3bbccf7af 100644
--- a/libraries/stdlib/genglsl/mx_screen.inline
+++ b/libraries/stdlib/genglsl/mx_screen.inline
@@ -1 +1 @@
-({{mix}}*((1.0 - (1.0 - {{fg}})) * (1.0 - {{bg}}))) + ((1.0-{{mix}})*{{bg}})
+({{mix}}*((1.0 - (1.0 - {{fg}}) * (1.0 - {{bg}})))) + ((1.0-{{mix}})*{{bg}})
diff --git a/libraries/stdlib/genmdl/stdlib_genmdl_impl.mtlx b/libraries/stdlib/genmdl/stdlib_genmdl_impl.mtlx
index bb792523b1..bf848d7b3d 100644
--- a/libraries/stdlib/genmdl/stdlib_genmdl_impl.mtlx
+++ b/libraries/stdlib/genmdl/stdlib_genmdl_impl.mtlx
@@ -562,8 +562,8 @@
   <implementation name="IM_dodge_color4_genmdl" nodedef="ND_dodge_color4" sourcecode="mx::stdlib::mx_dodge_color4({{fg}}, {{bg}}, {{mix}})" target="genmdl" />
 
   <!-- <screen> -->
-  <implementation name="IM_screen_float_genmdl" nodedef="ND_screen_float" sourcecode="({{mix}}*((1.0 - (1.0 - {{fg}})) * (1 - {{bg}}))) + ((1.0-{{mix}})*{{bg}})" target="genmdl" />
-  <implementation name="IM_screen_color3_genmdl" nodedef="ND_screen_color3" sourcecode="({{mix}}*((1.0 - (1.0 - {{fg}})) * (1 - {{bg}}))) + ((1.0-{{mix}})*{{bg}})" target="genmdl" />
+  <implementation name="IM_screen_float_genmdl" nodedef="ND_screen_float" sourcecode="({{mix}}*((1.0 - (1.0 - {{fg}}) * (1 - {{bg}})))) + ((1.0-{{mix}})*{{bg}})" target="genmdl" />
+  <implementation name="IM_screen_color3_genmdl" nodedef="ND_screen_color3" sourcecode="({{mix}}*((1.0 - (1.0 - {{fg}}) * (1 - {{bg}})))) + ((1.0-{{mix}})*{{bg}})" target="genmdl" />
   <implementation name="IM_screen_color4_genmdl" nodedef="ND_screen_color4" sourcecode="mx::stdlib::mx_screen_color4({{fg}}, {{bg}}, {{mix}})" target="genmdl" />
 
   <!-- <overlay> -->
diff --git a/libraries/stdlib/genosl/mx_screen.inline b/libraries/stdlib/genosl/mx_screen.inline
index 741b58d953..3a741aaba3 100644
--- a/libraries/stdlib/genosl/mx_screen.inline
+++ b/libraries/stdlib/genosl/mx_screen.inline
@@ -1 +1 @@
-({{mix}}*((1.0 - (1.0 - {{fg}})) * (1 - {{bg}}))) + ((1.0-{{mix}})*{{bg}})
+({{mix}}*((1.0 - (1.0 - {{fg}}) * (1 - {{bg}})))) + ((1.0-{{mix}})*{{bg}})
diff --git a/source/MaterialXGenMdl/mdl/materialx/stdlib.mdl b/source/MaterialXGenMdl/mdl/materialx/stdlib.mdl
index 5e022ec7d7..3df67214ba 100644
--- a/source/MaterialXGenMdl/mdl/materialx/stdlib.mdl
+++ b/source/MaterialXGenMdl/mdl/materialx/stdlib.mdl
@@ -2770,8 +2770,8 @@ export color4 mx_screen_color4(
 		anno::description("Node Group: compositing")
 	]]
 {
-	color rgb = (mxp_mix*((1.0 - (1.0 - mxp_fg.rgb)) * (1 - mxp_bg.rgb))) + ((1.0-mxp_mix)*mxp_bg.rgb);
-	float a   = (mxp_mix*((1.0 - (1.0 - mxp_fg.a  )) * (1 - mxp_bg.a  ))) + ((1.0-mxp_mix)*mxp_bg.a  );
+	color rgb = (mxp_mix*((1.0 - (1.0 - mxp_fg.rgb) * (1 - mxp_bg.rgb)))) + ((1.0-mxp_mix)*mxp_bg.rgb);
+	float a   = (mxp_mix*((1.0 - (1.0 - mxp_fg.a  ) * (1 - mxp_bg.a  )))) + ((1.0-mxp_mix)*mxp_bg.a  );
 	return color4(rgb,a);
 }