From 210266bc6f85816ae5723633206759bf4f336c42 Mon Sep 17 00:00:00 2001
From: Charlotte Manning <charlotte0m@gmail.com>
Date: Sat, 28 Sep 2024 20:08:15 -0700
Subject: [PATCH] Support transmission in translation from Standard Surface to
 glTF PBR (#2027)

This corrects the translation of transmission parameters from Standard Surface to glTF PBR.
Issue: https://github.com/AcademySoftwareFoundation/MaterialX/issues/1599
---
 .../standard_surface_to_gltf_pbr.mtlx         | 29 ++++++++++++++++---
 1 file changed, 25 insertions(+), 4 deletions(-)

diff --git a/libraries/bxdf/translation/standard_surface_to_gltf_pbr.mtlx b/libraries/bxdf/translation/standard_surface_to_gltf_pbr.mtlx
index 461e918400..51dfc6c634 100644
--- a/libraries/bxdf/translation/standard_surface_to_gltf_pbr.mtlx
+++ b/libraries/bxdf/translation/standard_surface_to_gltf_pbr.mtlx
@@ -76,12 +76,24 @@
     </dotproduct>
 
     <!-- Metallic roughness -->
-    <ifequal name="base_color" type="color3">
+    <ifequal name="baseColor" type="color3">
       <input name="value1" type="float" nodename="hasCoatColor" />
       <input name="value2" type="float" value="0" />
       <input name="in1" type="color3" nodename="scaledBaseColor" />
       <input name="in2" type="color3" nodename="mixedBaseColor" />
     </ifequal>
+    <ifgreater name="transmissionBaseColor" type="color3">
+      <input name="value1" type="float" interfacename="transmission_depth" />
+      <input name="value2" type="float" value="0" />
+      <input name="in1" type="color3" value="1, 1, 1" />
+      <input name="in2" type="color3" interfacename="transmission_color" />
+    </ifgreater>
+    <ifgreater name="base_color" type="color3">
+      <input name="value1" type="float" interfacename="transmission" />
+      <input name="value2" type="float" value="0" />
+      <input name="in1" type="color3" nodename="transmissionBaseColor" />
+      <input name="in2" type="color3" nodename="baseColor" />
+    </ifgreater>
     <dot name="metallic" type="float">
       <input name="in" type="float" interfacename="metalness" />
     </dot>
@@ -96,9 +108,18 @@
     <dot name="thickness" type="float">
       <input name="in" type="float" interfacename="transmission_depth" />
     </dot>
-    <dot name="attenuation_color" type="color3">
-      <input name="in" type="color3" interfacename="transmission_color" />
-    </dot>
+    <ifgreater name="transmissionAttenuationColor" type="color3">
+      <input name="value1" type="float" interfacename="transmission_depth" />
+      <input name="value2" type="float" value="0" />
+      <input name="in1" type="color3" interfacename="transmission_color" />
+      <input name="in2" type="color3" value="1, 1, 1" />
+    </ifgreater>
+    <ifgreater name="attenuation_color" type="color3">
+      <input name="value1" type="float" interfacename="transmission" />
+      <input name="value2" type="float" value="0" />
+      <input name="in1" type="color3" nodename="transmissionAttenuationColor" />
+      <input name="in2" type="color3" value="1, 1, 1" />
+    </ifgreater>
 
     <!-- Sheen -->
     <multiply name="sheen_color" type="color3">