From f8ceb6346e41d5744901e9cc27e40f544e625646 Mon Sep 17 00:00:00 2001
From: Bernard Kwok <kwokcb@gmail.com>
Date: Wed, 21 May 2025 15:45:16 -0400
Subject: [PATCH 1/3] Initial test.

---
 libraries/stdlib/stdlib_defs.mtlx   | 207 ++++++++++++++++++++++++++++
 libraries/stdlib/stdlib_ng.mtlx     | 189 +------------------------
 source/MaterialXCore/Definition.cpp |   6 +
 source/MaterialXCore/Document.cpp   |  25 +++-
 source/MaterialXCore/Node.cpp       |   9 +-
 5 files changed, 244 insertions(+), 192 deletions(-)

diff --git a/libraries/stdlib/stdlib_defs.mtlx b/libraries/stdlib/stdlib_defs.mtlx
index e8d5029965..e96abb216b 100644
--- a/libraries/stdlib/stdlib_defs.mtlx
+++ b/libraries/stdlib/stdlib_defs.mtlx
@@ -2148,56 +2148,263 @@
     <input name="in1" type="float" value="0.0" />
     <input name="in2" type="float" value="1.0" />
     <output name="out" type="float" defaultinput="in1" />
+
+    <nodegraph name="NG_safepower_float">
+      <sign name="sign_in1" type="float">
+        <input name="in" type="float" interfacename="in1" />
+      </sign>
+      <absval name="abs_in1" type="float">
+        <input name="in" type="float" interfacename="in1" />
+      </absval>
+      <power name="power" type="float">
+        <input name="in1" type="float" nodename="abs_in1" />
+        <input name="in2" type="float" interfacename="in2" />
+      </power>
+      <multiply name="safepower" type="float">
+        <input name="in1" type="float" nodename="sign_in1" />
+        <input name="in2" type="float" nodename="power" />
+      </multiply>
+      <output name="out" type="float" nodename="safepower" />
+    </nodegraph>
+    
   </nodedef>
   <nodedef name="ND_safepower_color3" node="safepower" nodegroup="math">
     <input name="in1" type="color3" value="0.0, 0.0, 0.0" />
     <input name="in2" type="color3" value="1.0, 1.0, 1.0" />
     <output name="out" type="color3" defaultinput="in1" />
+
+    <nodegraph name="NG_safepower_color3">
+      <sign name="sign_in1" type="color3">
+        <input name="in" type="color3" interfacename="in1" />
+      </sign>
+      <absval name="abs_in1" type="color3">
+        <input name="in" type="color3" interfacename="in1" />
+      </absval>
+      <power name="power" type="color3">
+        <input name="in1" type="color3" nodename="abs_in1" />
+        <input name="in2" type="color3" interfacename="in2" />
+      </power>
+      <multiply name="safepower" type="color3">
+        <input name="in1" type="color3" nodename="sign_in1" />
+        <input name="in2" type="color3" nodename="power" />
+      </multiply>
+      <output name="out" type="color3" nodename="safepower" />
+    </nodegraph>
+
   </nodedef>
   <nodedef name="ND_safepower_color4" node="safepower" nodegroup="math">
     <input name="in1" type="color4" value="0.0, 0.0, 0.0, 0.0" />
     <input name="in2" type="color4" value="1.0, 1.0, 1.0, 1.0" />
     <output name="out" type="color4" defaultinput="in1" />
+
+    <nodegraph name="NG_safepower_color4" >
+      <sign name="sign_in1" type="color4">
+        <input name="in" type="color4" interfacename="in1" />
+      </sign>
+      <absval name="abs_in1" type="color4">
+        <input name="in" type="color4" interfacename="in1" />
+      </absval>
+      <power name="power" type="color4">
+        <input name="in1" type="color4" nodename="abs_in1" />
+        <input name="in2" type="color4" interfacename="in2" />
+      </power>
+      <multiply name="safepower" type="color4">
+        <input name="in1" type="color4" nodename="sign_in1" />
+        <input name="in2" type="color4" nodename="power" />
+      </multiply>
+      <output name="out" type="color4" nodename="safepower" />
+    </nodegraph>
+
   </nodedef>
   <nodedef name="ND_safepower_vector2" node="safepower" nodegroup="math">
     <input name="in1" type="vector2" value="0.0, 0.0" />
     <input name="in2" type="vector2" value="1.0, 1.0" />
     <output name="out" type="vector2" defaultinput="in1" />
+
+    <nodegraph name="NG_safepower_vector2" >
+      <sign name="sign_in1" type="vector2">
+        <input name="in" type="vector2" interfacename="in1" />
+      </sign>
+      <absval name="abs_in1" type="vector2">
+        <input name="in" type="vector2" interfacename="in1" />
+      </absval>
+      <power name="power" type="vector2">
+        <input name="in1" type="vector2" nodename="abs_in1" />
+        <input name="in2" type="vector2" interfacename="in2" />
+      </power>
+      <multiply name="safepower" type="vector2">
+        <input name="in1" type="vector2" nodename="sign_in1" />
+        <input name="in2" type="vector2" nodename="power" />
+      </multiply>
+      <output name="out" type="vector2" nodename="safepower" />
+    </nodegraph>
+
   </nodedef>
   <nodedef name="ND_safepower_vector3" node="safepower" nodegroup="math">
     <input name="in1" type="vector3" value="0.0, 0.0, 0.0" />
     <input name="in2" type="vector3" value="1.0, 1.0, 1.0" />
     <output name="out" type="vector3" defaultinput="in1" />
+
+    <nodegraph name="NG_safepower_vector3" >
+      <sign name="sign_in1" type="vector3">
+        <input name="in" type="vector3" interfacename="in1" />
+      </sign>
+      <absval name="abs_in1" type="vector3">
+        <input name="in" type="vector3" interfacename="in1" />
+      </absval>
+      <power name="power" type="vector3">
+        <input name="in1" type="vector3" nodename="abs_in1" />
+        <input name="in2" type="vector3" interfacename="in2" />
+      </power>
+      <multiply name="safepower" type="vector3">
+        <input name="in1" type="vector3" nodename="sign_in1" />
+        <input name="in2" type="vector3" nodename="power" />
+      </multiply>
+      <output name="out" type="vector3" nodename="safepower" />
+    </nodegraph>
+
   </nodedef>
   <nodedef name="ND_safepower_vector4" node="safepower" nodegroup="math">
     <input name="in1" type="vector4" value="0.0, 0.0, 0.0, 0.0" />
     <input name="in2" type="vector4" value="1.0, 1.0, 1.0, 1.0" />
     <output name="out" type="vector4" defaultinput="in1" />
+
+    <nodegraph name="NG_safepower_vector4" >
+      <sign name="sign_in1" type="vector4">
+        <input name="in" type="vector4" interfacename="in1" />
+      </sign>
+      <absval name="abs_in1" type="vector4">
+        <input name="in" type="vector4" interfacename="in1" />
+      </absval>
+      <power name="power" type="vector4">
+        <input name="in1" type="vector4" nodename="abs_in1" />
+        <input name="in2" type="vector4" interfacename="in2" />
+      </power>
+      <multiply name="safepower" type="vector4">
+        <input name="in1" type="vector4" nodename="sign_in1" />
+        <input name="in2" type="vector4" nodename="power" />
+      </multiply>
+      <output name="out" type="vector4" nodename="safepower" />
+    </nodegraph>
+
   </nodedef>
   <nodedef name="ND_safepower_color3FA" node="safepower" nodegroup="math">
     <input name="in1" type="color3" value="0.0, 0.0, 0.0" />
     <input name="in2" type="float" value="1.0" />
     <output name="out" type="color3" defaultinput="in1" />
+
+    <nodegraph name="NG_safepower_color3FA" >
+      <sign name="sign_in1" type="color3">
+        <input name="in" type="color3" interfacename="in1" />
+      </sign>
+      <absval name="abs_in1" type="color3">
+        <input name="in" type="color3" interfacename="in1" />
+      </absval>
+      <power name="power" type="color3">
+        <input name="in1" type="color3" nodename="abs_in1" />
+        <input name="in2" type="float" interfacename="in2" />
+      </power>
+      <multiply name="safepower" type="color3">
+        <input name="in1" type="color3" nodename="sign_in1" />
+        <input name="in2" type="color3" nodename="power" />
+      </multiply>
+      <output name="out" type="color3" nodename="safepower" />
+    </nodegraph>
   </nodedef>
   <nodedef name="ND_safepower_color4FA" node="safepower" nodegroup="math">
     <input name="in1" type="color4" value="0.0, 0.0, 0.0, 0.0" />
     <input name="in2" type="float" value="1.0" />
     <output name="out" type="color4" defaultinput="in1" />
+
+    <nodegraph name="NG_safepower_color4FA" >
+      <sign name="sign_in1" type="color4">
+        <input name="in" type="color4" interfacename="in1" />
+      </sign>
+      <absval name="abs_in1" type="color4">
+        <input name="in" type="color4" interfacename="in1" />
+      </absval>
+      <power name="power" type="color4">
+        <input name="in1" type="color4" nodename="abs_in1" />
+        <input name="in2" type="float" interfacename="in2" />
+      </power>
+      <multiply name="safepower" type="color4">
+        <input name="in1" type="color4" nodename="sign_in1" />
+        <input name="in2" type="color4" nodename="power" />
+      </multiply>
+      <output name="out" type="color4" nodename="safepower" />
+    </nodegraph>
+
   </nodedef>
   <nodedef name="ND_safepower_vector2FA" node="safepower" nodegroup="math">
     <input name="in1" type="vector2" value="0.0, 0.0" />
     <input name="in2" type="float" value="1.0" />
     <output name="out" type="vector2" defaultinput="in1" />
+
+    <nodegraph name="NG_safepower_vector2FA">
+      <sign name="sign_in1" type="vector2">
+        <input name="in" type="vector2" interfacename="in1" />
+      </sign>
+      <absval name="abs_in1" type="vector2">
+        <input name="in" type="vector2" interfacename="in1" />
+      </absval>
+      <power name="power" type="vector2">
+        <input name="in1" type="vector2" nodename="abs_in1" />
+        <input name="in2" type="float" interfacename="in2" />
+      </power>
+      <multiply name="safepower" type="vector2">
+        <input name="in1" type="vector2" nodename="sign_in1" />
+        <input name="in2" type="vector2" nodename="power" />
+      </multiply>
+      <output name="out" type="vector2" nodename="safepower" />
+    </nodegraph>
+
   </nodedef>
   <nodedef name="ND_safepower_vector3FA" node="safepower" nodegroup="math">
     <input name="in1" type="vector3" value="0.0, 0.0, 0.0" />
     <input name="in2" type="float" value="1.0" />
     <output name="out" type="vector3" defaultinput="in1" />
+
+    <nodegraph name="NG_safepower_vector3FA" >
+      <sign name="sign_in1" type="vector3">
+        <input name="in" type="vector3" interfacename="in1" />
+      </sign>
+      <absval name="abs_in1" type="vector3">
+        <input name="in" type="vector3" interfacename="in1" />
+      </absval>
+      <power name="power" type="vector3">
+        <input name="in1" type="vector3" nodename="abs_in1" />
+        <input name="in2" type="float" interfacename="in2" />
+      </power>
+      <multiply name="safepower" type="vector3">
+        <input name="in1" type="vector3" nodename="sign_in1" />
+        <input name="in2" type="vector3" nodename="power" />
+      </multiply>
+      <output name="out" type="vector3" nodename="safepower" />
+    </nodegraph>
+
   </nodedef>
   <nodedef name="ND_safepower_vector4FA" node="safepower" nodegroup="math">
     <input name="in1" type="vector4" value="0.0, 0.0, 0.0, 0.0" />
     <input name="in2" type="float" value="1.0" />
     <output name="out" type="vector4" defaultinput="in1" />
+
+    <nodegraph name="NG_safepower_vector4FA">
+      <sign name="sign_in1" type="vector4">
+        <input name="in" type="vector4" interfacename="in1" />
+      </sign>
+      <absval name="abs_in1" type="vector4">
+        <input name="in" type="vector4" interfacename="in1" />
+      </absval>
+      <power name="power" type="vector4">
+        <input name="in1" type="vector4" nodename="abs_in1" />
+        <input name="in2" type="float" interfacename="in2" />
+      </power>
+      <multiply name="safepower" type="vector4">
+        <input name="in1" type="vector4" nodename="sign_in1" />
+        <input name="in2" type="vector4" nodename="power" />
+      </multiply>
+      <output name="out" type="vector4" nodename="safepower" />
+    </nodegraph>
   </nodedef>
 
   <!--
diff --git a/libraries/stdlib/stdlib_ng.mtlx b/libraries/stdlib/stdlib_ng.mtlx
index 55de4d17d1..af80ea866a 100644
--- a/libraries/stdlib/stdlib_ng.mtlx
+++ b/libraries/stdlib/stdlib_ng.mtlx
@@ -3434,194 +3434,7 @@
     Raise incoming half/float/color/vector values to the "in2" power.
     Negative "in1" values will result in negative output values. ie. out = sign(in1)*pow(abs(in1),in2)
   -->
-  <nodegraph name="NG_safepower_float" nodedef="ND_safepower_float">
-    <sign name="sign_in1" type="float">
-      <input name="in" type="float" interfacename="in1" />
-    </sign>
-    <absval name="abs_in1" type="float">
-      <input name="in" type="float" interfacename="in1" />
-    </absval>
-    <power name="power" type="float">
-      <input name="in1" type="float" nodename="abs_in1" />
-      <input name="in2" type="float" interfacename="in2" />
-    </power>
-    <multiply name="safepower" type="float">
-      <input name="in1" type="float" nodename="sign_in1" />
-      <input name="in2" type="float" nodename="power" />
-    </multiply>
-    <output name="out" type="float" nodename="safepower" />
-  </nodegraph>
-  <nodegraph name="NG_safepower_color3" nodedef="ND_safepower_color3">
-    <sign name="sign_in1" type="color3">
-      <input name="in" type="color3" interfacename="in1" />
-    </sign>
-    <absval name="abs_in1" type="color3">
-      <input name="in" type="color3" interfacename="in1" />
-    </absval>
-    <power name="power" type="color3">
-      <input name="in1" type="color3" nodename="abs_in1" />
-      <input name="in2" type="color3" interfacename="in2" />
-    </power>
-    <multiply name="safepower" type="color3">
-      <input name="in1" type="color3" nodename="sign_in1" />
-      <input name="in2" type="color3" nodename="power" />
-    </multiply>
-    <output name="out" type="color3" nodename="safepower" />
-  </nodegraph>
-  <nodegraph name="NG_safepower_color4" nodedef="ND_safepower_color4">
-    <sign name="sign_in1" type="color4">
-      <input name="in" type="color4" interfacename="in1" />
-    </sign>
-    <absval name="abs_in1" type="color4">
-      <input name="in" type="color4" interfacename="in1" />
-    </absval>
-    <power name="power" type="color4">
-      <input name="in1" type="color4" nodename="abs_in1" />
-      <input name="in2" type="color4" interfacename="in2" />
-    </power>
-    <multiply name="safepower" type="color4">
-      <input name="in1" type="color4" nodename="sign_in1" />
-      <input name="in2" type="color4" nodename="power" />
-    </multiply>
-    <output name="out" type="color4" nodename="safepower" />
-  </nodegraph>
-  <nodegraph name="NG_safepower_vector2" nodedef="ND_safepower_vector2">
-    <sign name="sign_in1" type="vector2">
-      <input name="in" type="vector2" interfacename="in1" />
-    </sign>
-    <absval name="abs_in1" type="vector2">
-      <input name="in" type="vector2" interfacename="in1" />
-    </absval>
-    <power name="power" type="vector2">
-      <input name="in1" type="vector2" nodename="abs_in1" />
-      <input name="in2" type="vector2" interfacename="in2" />
-    </power>
-    <multiply name="safepower" type="vector2">
-      <input name="in1" type="vector2" nodename="sign_in1" />
-      <input name="in2" type="vector2" nodename="power" />
-    </multiply>
-    <output name="out" type="vector2" nodename="safepower" />
-  </nodegraph>
-  <nodegraph name="NG_safepower_vector3" nodedef="ND_safepower_vector3">
-    <sign name="sign_in1" type="vector3">
-      <input name="in" type="vector3" interfacename="in1" />
-    </sign>
-    <absval name="abs_in1" type="vector3">
-      <input name="in" type="vector3" interfacename="in1" />
-    </absval>
-    <power name="power" type="vector3">
-      <input name="in1" type="vector3" nodename="abs_in1" />
-      <input name="in2" type="vector3" interfacename="in2" />
-    </power>
-    <multiply name="safepower" type="vector3">
-      <input name="in1" type="vector3" nodename="sign_in1" />
-      <input name="in2" type="vector3" nodename="power" />
-    </multiply>
-    <output name="out" type="vector3" nodename="safepower" />
-  </nodegraph>
-  <nodegraph name="NG_safepower_vector4" nodedef="ND_safepower_vector4">
-    <sign name="sign_in1" type="vector4">
-      <input name="in" type="vector4" interfacename="in1" />
-    </sign>
-    <absval name="abs_in1" type="vector4">
-      <input name="in" type="vector4" interfacename="in1" />
-    </absval>
-    <power name="power" type="vector4">
-      <input name="in1" type="vector4" nodename="abs_in1" />
-      <input name="in2" type="vector4" interfacename="in2" />
-    </power>
-    <multiply name="safepower" type="vector4">
-      <input name="in1" type="vector4" nodename="sign_in1" />
-      <input name="in2" type="vector4" nodename="power" />
-    </multiply>
-    <output name="out" type="vector4" nodename="safepower" />
-  </nodegraph>
-  <nodegraph name="NG_safepower_color3FA" nodedef="ND_safepower_color3FA">
-    <sign name="sign_in1" type="color3">
-      <input name="in" type="color3" interfacename="in1" />
-    </sign>
-    <absval name="abs_in1" type="color3">
-      <input name="in" type="color3" interfacename="in1" />
-    </absval>
-    <power name="power" type="color3">
-      <input name="in1" type="color3" nodename="abs_in1" />
-      <input name="in2" type="float" interfacename="in2" />
-    </power>
-    <multiply name="safepower" type="color3">
-      <input name="in1" type="color3" nodename="sign_in1" />
-      <input name="in2" type="color3" nodename="power" />
-    </multiply>
-    <output name="out" type="color3" nodename="safepower" />
-  </nodegraph>
-  <nodegraph name="NG_safepower_color4FA" nodedef="ND_safepower_color4FA">
-    <sign name="sign_in1" type="color4">
-      <input name="in" type="color4" interfacename="in1" />
-    </sign>
-    <absval name="abs_in1" type="color4">
-      <input name="in" type="color4" interfacename="in1" />
-    </absval>
-    <power name="power" type="color4">
-      <input name="in1" type="color4" nodename="abs_in1" />
-      <input name="in2" type="float" interfacename="in2" />
-    </power>
-    <multiply name="safepower" type="color4">
-      <input name="in1" type="color4" nodename="sign_in1" />
-      <input name="in2" type="color4" nodename="power" />
-    </multiply>
-    <output name="out" type="color4" nodename="safepower" />
-  </nodegraph>
-  <nodegraph name="NG_safepower_vector2FA" nodedef="ND_safepower_vector2FA">
-    <sign name="sign_in1" type="vector2">
-      <input name="in" type="vector2" interfacename="in1" />
-    </sign>
-    <absval name="abs_in1" type="vector2">
-      <input name="in" type="vector2" interfacename="in1" />
-    </absval>
-    <power name="power" type="vector2">
-      <input name="in1" type="vector2" nodename="abs_in1" />
-      <input name="in2" type="float" interfacename="in2" />
-    </power>
-    <multiply name="safepower" type="vector2">
-      <input name="in1" type="vector2" nodename="sign_in1" />
-      <input name="in2" type="vector2" nodename="power" />
-    </multiply>
-    <output name="out" type="vector2" nodename="safepower" />
-  </nodegraph>
-  <nodegraph name="NG_safepower_vector3FA" nodedef="ND_safepower_vector3FA">
-    <sign name="sign_in1" type="vector3">
-      <input name="in" type="vector3" interfacename="in1" />
-    </sign>
-    <absval name="abs_in1" type="vector3">
-      <input name="in" type="vector3" interfacename="in1" />
-    </absval>
-    <power name="power" type="vector3">
-      <input name="in1" type="vector3" nodename="abs_in1" />
-      <input name="in2" type="float" interfacename="in2" />
-    </power>
-    <multiply name="safepower" type="vector3">
-      <input name="in1" type="vector3" nodename="sign_in1" />
-      <input name="in2" type="vector3" nodename="power" />
-    </multiply>
-    <output name="out" type="vector3" nodename="safepower" />
-  </nodegraph>
-  <nodegraph name="NG_safepower_vector4FA" nodedef="ND_safepower_vector4FA">
-    <sign name="sign_in1" type="vector4">
-      <input name="in" type="vector4" interfacename="in1" />
-    </sign>
-    <absval name="abs_in1" type="vector4">
-      <input name="in" type="vector4" interfacename="in1" />
-    </absval>
-    <power name="power" type="vector4">
-      <input name="in1" type="vector4" nodename="abs_in1" />
-      <input name="in2" type="float" interfacename="in2" />
-    </power>
-    <multiply name="safepower" type="vector4">
-      <input name="in1" type="vector4" nodename="sign_in1" />
-      <input name="in2" type="vector4" nodename="power" />
-    </multiply>
-    <output name="out" type="vector4" nodename="safepower" />
-  </nodegraph>
-
+  
   <!--
     Node: <contrast>
     Increase or decrease contrast of a float/color value using a linear slope multiplier.
diff --git a/source/MaterialXCore/Definition.cpp b/source/MaterialXCore/Definition.cpp
index da6c3ca3af..f4096f9d84 100644
--- a/source/MaterialXCore/Definition.cpp
+++ b/source/MaterialXCore/Definition.cpp
@@ -156,6 +156,12 @@ void Implementation::setNodeDef(ConstNodeDefPtr nodeDef)
 
 NodeDefPtr Implementation::getNodeDef() const
 {
+    ElementPtr parent = getSelfNonConst()->getParent();
+    NodeDefPtr nodedef = parent->asA<NodeDef>();
+    if (nodedef)
+    {
+        return nodedef;
+    }
     return resolveNameReference<NodeDef>(getNodeDefString());
 }
 
diff --git a/source/MaterialXCore/Document.cpp b/source/MaterialXCore/Document.cpp
index 0206ca6ca9..bccacd3a88 100644
--- a/source/MaterialXCore/Document.cpp
+++ b/source/MaterialXCore/Document.cpp
@@ -45,6 +45,7 @@ class Document::Cache
             portElementMap.clear();
             nodeDefMap.clear();
             implementationMap.clear();
+            std::unordered_map<string, std::vector<InterfaceElementPtr>> nonFuncNodeDefMap;
 
             // Traverse the document to build a new cache.
             for (ElementPtr elem : doc.lock()->traverseTree())
@@ -79,6 +80,14 @@ class Document::Cache
                     if (nodeDef)
                     {
                         nodeDefMap[nodeDef->getQualifiedName(nodeString)].push_back(nodeDef);
+
+                        // Look for child nodegraph implementations
+                        vector<NodeGraphPtr> nodeGraphs = nodeDef->getChildrenOfType<NodeGraph>();
+                        for (NodeGraphPtr nodeGraph : nodeGraphs)
+                        {
+                            implementationMap[elem->getName()].push_back(nodeGraph);
+                        }
+                            
                     }
                 }
                 if (!nodeDefString.empty())
@@ -88,7 +97,7 @@ class Document::Cache
                     {
                         if (interface->isA<NodeGraph>())
                         {
-                            implementationMap[interface->getQualifiedName(nodeDefString)].push_back(interface);
+                            nonFuncNodeDefMap[interface->getQualifiedName(nodeDefString)].push_back(interface);
                         }
                         ImplementationPtr impl = interface->asA<Implementation>();
                         if (impl)
@@ -99,17 +108,27 @@ class Document::Cache
                             {
                                 NodeGraphPtr nodeGraph = impl->getDocument()->getNodeGraph(nodeGraphString);
                                 if (nodeGraph)
-                                    implementationMap[interface->getQualifiedName(nodeDefString)].push_back(nodeGraph);
+                                    nonFuncNodeDefMap[interface->getQualifiedName(nodeDefString)].push_back(nodeGraph);
                             }
                             else
                             {
-                                implementationMap[interface->getQualifiedName(nodeDefString)].push_back(interface);
+                                nonFuncNodeDefMap[interface->getQualifiedName(nodeDefString)].push_back(interface);
                             }
                         }
                     }
                 }
             }
 
+            // Functional node definitions have precedence over non-functional ones
+            // So append them to the end of the implementation list assocaited 
+            // with any existing nodedef entry (or create a new one if does not exist).
+            //
+            for (const auto& [nodedefKey, appendImplementations] : nonFuncNodeDefMap)
+            {
+                auto& implementations = implementationMap[nodedefKey];
+                implementations.insert(implementations.end(), appendImplementations.begin(), appendImplementations.end());
+            }
+
             valid = true;
         }
     }
diff --git a/source/MaterialXCore/Node.cpp b/source/MaterialXCore/Node.cpp
index 09d7114098..313bf7183a 100644
--- a/source/MaterialXCore/Node.cpp
+++ b/source/MaterialXCore/Node.cpp
@@ -719,7 +719,14 @@ void NodeGraph::modifyInterfaceName(const string& inputPath, const string& inter
 
 NodeDefPtr NodeGraph::getNodeDef() const
 {
-    NodeDefPtr nodedef = resolveNameReference<NodeDef>(getNodeDefString());
+    ElementPtr parent = getSelfNonConst()->getParent();
+    NodeDefPtr nodedef = parent->asA<NodeDef>();
+    if (nodedef)
+    {
+        return nodedef;
+    }
+
+    nodedef = resolveNameReference<NodeDef>(getNodeDefString());
     // If not directly defined look for an implementation which has a nodedef association
     if (!nodedef)
     {

From cad97bc898aafbcf6ab6e146f1b9dcaa389556e8 Mon Sep 17 00:00:00 2001
From: Bernard Kwok <kwokcb@gmail.com>
Date: Fri, 5 Sep 2025 08:43:52 -0400
Subject: [PATCH 2/3] Add create options and unit test.

---
 source/MaterialXCore/Document.cpp             | 23 +++++++++----
 source/MaterialXCore/Document.h               | 14 +++++++-
 source/MaterialXTest/MaterialXCore/Node.cpp   | 34 ++++++++++++++++---
 .../PyMaterialXCore/PyDocument.cpp            |  5 ++-
 4 files changed, 63 insertions(+), 13 deletions(-)

diff --git a/source/MaterialXCore/Document.cpp b/source/MaterialXCore/Document.cpp
index bccacd3a88..a86f0589e2 100644
--- a/source/MaterialXCore/Document.cpp
+++ b/source/MaterialXCore/Document.cpp
@@ -166,7 +166,8 @@ void Document::initialize()
 }
 
 NodeDefPtr Document::addNodeDefFromGraph(NodeGraphPtr nodeGraph, const string& nodeDefName,
-                                         const string& category, const string& newGraphName)
+                                         const string& category, const string& newGraphName,
+                                         DefinitionOptions *options)
 {
     if (category.empty())
     {
@@ -178,14 +179,20 @@ NodeDefPtr Document::addNodeDefFromGraph(NodeGraphPtr nodeGraph, const string& n
         throw Exception("Cannot create duplicate nodedef: " + nodeDefName);
     }
 
-    if (getNodeGraph(newGraphName))
+    bool addAsChild = options ? options->addImplementationAsChild : false;
+
+    if (!addAsChild && getNodeGraph(newGraphName))
     {
         throw Exception("Cannot create duplicate nodegraph: " + newGraphName);
     }
 
+    // Create a new nodedef and set its category
+    NodeDefPtr nodeDef = addNodeDef(nodeDefName, EMPTY_STRING);
+    nodeDef->setNodeString(category);
+
     // Create a new functional nodegraph, and copy over the
     // contents from the compound nodegraph
-    NodeGraphPtr graph = addNodeGraph(newGraphName);
+    NodeGraphPtr graph = !addAsChild ? addNodeGraph(newGraphName) : nodeDef->addChild<NodeGraph>(newGraphName);
     graph->copyContentFrom(nodeGraph);
 
     for (auto graphChild : graph->getChildren())
@@ -193,11 +200,13 @@ NodeDefPtr Document::addNodeDefFromGraph(NodeGraphPtr nodeGraph, const string& n
         graphChild->removeAttribute(Element::XPOS_ATTRIBUTE);
         graphChild->removeAttribute(Element::YPOS_ATTRIBUTE);
     }
-    graph->setNodeDefString(nodeDefName);
 
-    // Create a new nodedef and set its category
-    NodeDefPtr nodeDef = addNodeDef(nodeDefName, EMPTY_STRING);
-    nodeDef->setNodeString(category);
+    // Reference from nodegraph to nodedef is not required
+    // as the graph is a child of the nodedef.
+    if (!addAsChild)
+    {
+        graph->setNodeDefString(nodeDefName);
+    }
 
     // Expose any existing interfaces from the graph.
     // Any connection attributes ("nodegraph", "nodename", "interfacename") on the
diff --git a/source/MaterialXCore/Document.h b/source/MaterialXCore/Document.h
index ab01bbbc11..a385499c5a 100644
--- a/source/MaterialXCore/Document.h
+++ b/source/MaterialXCore/Document.h
@@ -23,6 +23,8 @@ using DocumentPtr = shared_ptr<Document>;
 /// A shared pointer to a const Document
 using ConstDocumentPtr = shared_ptr<const Document>;
 
+class DefinitionOptions;
+
 /// @class Document
 /// A MaterialX document, which represents the top-level element in the
 /// MaterialX ownership hierarchy.
@@ -363,7 +365,8 @@ class MX_CORE_API Document : public GraphElement
     /// @param category Category of the new NodeDef
     /// @return New declaration if successful.
     NodeDefPtr addNodeDefFromGraph(NodeGraphPtr nodeGraph, const string& nodeDefName,
-                                   const string& category, const string& newGraphName);
+                                   const string& category, const string& newGraphName,
+                                   DefinitionOptions * options = nullptr);
 
     /// Return the NodeDef, if any, with the given name.
     NodeDefPtr getNodeDef(const string& name) const
@@ -708,6 +711,15 @@ class MX_CORE_API Document : public GraphElement
     std::unique_ptr<Cache> _cache;
 };
 
+/// @class DefinitionOptions
+/// Options for defining a NodeDef from an immplementation
+class MX_CORE_API DefinitionOptions
+{
+public:
+    /// Add implementation as child of NodeDef as opposed a sibliing.
+    bool addImplementationAsChild = false;
+};
+
 /// Create a new Document.
 /// @relates Document
 MX_CORE_API DocumentPtr createDocument();
diff --git a/source/MaterialXTest/MaterialXCore/Node.cpp b/source/MaterialXTest/MaterialXCore/Node.cpp
index 6031799afb..77c686637d 100644
--- a/source/MaterialXTest/MaterialXCore/Node.cpp
+++ b/source/MaterialXTest/MaterialXCore/Node.cpp
@@ -675,7 +675,7 @@ TEST_CASE("Organization", "[nodegraph]")
     CHECK(nodeGraph->getBackdrops().empty());
 }
 
-TEST_CASE("Node Definition Creation", "[nodedef]")
+void testNodeDefCreationFromGraph(mx::DefinitionOptions options)
 {
     mx::FileSearchPath searchPath = mx::getDefaultDataSearchPath();
     mx::DocumentPtr stdlib = mx::createDocument();
@@ -714,10 +714,12 @@ TEST_CASE("Node Definition Creation", "[nodedef]")
         bool isDefaultVersion = false;
         const std::string NODENAME = graph->getName();
 
+
         // Create a new functional graph and definition from a compound graph
+        bool addAsChild = options.addImplementationAsChild;
         std::string newNodeDefName = doc->createValidChildName("ND_" + graph->getName());
         std::string newGraphName = doc->createValidChildName("NG_" + graph->getName());
-        mx::NodeDefPtr nodeDef = doc->addNodeDefFromGraph(graph, newNodeDefName, NODENAME, newGraphName);
+        mx::NodeDefPtr nodeDef = doc->addNodeDefFromGraph(graph, newNodeDefName, NODENAME, newGraphName, &options);
         REQUIRE(nodeDef != nullptr);
         nodeDef->setVersionString(VERSION1);
         nodeDef->setDefaultVersion(isDefaultVersion);
@@ -759,9 +761,16 @@ TEST_CASE("Node Definition Creation", "[nodedef]")
         }
 
         // Check validity of new functional nodegraph
-        mx::NodeGraphPtr newGraph = doc->getNodeGraph(newGraphName);
+        mx::NodeGraphPtr newGraph = !addAsChild ? doc->getNodeGraph(newGraphName) : nodeDef->getChildOfType<mx::NodeGraph>(newGraphName);
         REQUIRE(newGraph != nullptr);
-        REQUIRE(newGraph->getNodeDefString() == newNodeDefName);
+        if (!addAsChild)
+        {
+            REQUIRE(newGraph->getNodeDefString() == newNodeDefName);
+        }
+        else
+        {
+            REQUIRE(newGraph->getNodeDefString().empty());
+        }
         mx::ConstInterfaceElementPtr decl = newGraph->getDeclaration();
         REQUIRE(decl->getName() == nodeDef->getName());
         REQUIRE(doc->validate());
@@ -826,6 +835,23 @@ TEST_CASE("Node Definition Creation", "[nodedef]")
     REQUIRE(doc->validate());
 }
 
+TEST_CASE("Node Definition Creation", "[nodedef_create]")
+{
+    mx::DefinitionOptions defOptions;
+
+    SECTION("Without implementation as child")
+    {
+        defOptions.addImplementationAsChild = false;
+        testNodeDefCreationFromGraph(defOptions);
+    }
+
+    SECTION("With implementation as child")
+    {
+        defOptions.addImplementationAsChild = true;
+        testNodeDefCreationFromGraph(defOptions);
+    }
+}
+
 TEST_CASE("Set Name Global", "[node, nodegraph]")
 {
     mx::DocumentPtr doc = mx::createDocument();
diff --git a/source/PyMaterialX/PyMaterialXCore/PyDocument.cpp b/source/PyMaterialX/PyMaterialXCore/PyDocument.cpp
index e021bc92de..caadcd77ff 100644
--- a/source/PyMaterialX/PyMaterialXCore/PyDocument.cpp
+++ b/source/PyMaterialX/PyMaterialXCore/PyDocument.cpp
@@ -26,6 +26,9 @@ void bindPyDocument(py::module& mod)
 {
     mod.def("createDocument", &mx::createDocument);
 
+    py::class_<mx::DefinitionOptions>(mod, "DefinitionOptions")
+        .def_readwrite("addImplementationAsChild", &mx::DefinitionOptions::addImplementationAsChild);
+
     py::class_<mx::Document, mx::DocumentPtr, mx::GraphElement>(mod, "Document")
         .def("initialize", &mx::Document::initialize)
         .def("copy", &mx::Document::copy)
@@ -74,7 +77,7 @@ void bindPyDocument(py::module& mod)
         .def("removeTypeDef", &mx::Document::removeTypeDef)
         .def("addNodeDef", &mx::Document::addNodeDef,
             py::arg("name") = mx::EMPTY_STRING, py::arg("type") = mx::DEFAULT_TYPE_STRING, py::arg("node") = mx::EMPTY_STRING)
-        .def("addNodeDefFromGraph", (mx::NodeDefPtr (mx::Document::*)(mx::NodeGraphPtr, const std::string&, const std::string&, const std::string&)) & mx::Document::addNodeDefFromGraph)
+        .def("addNodeDefFromGraph", (mx::NodeDefPtr (mx::Document::*)(mx::NodeGraphPtr, const std::string&, const std::string&, const std::string&, mx::DefinitionOptions*)) & mx::Document::addNodeDefFromGraph)
         .def("addNodeDefFromGraph", (mx::NodeDefPtr(mx::Document::*)(mx::NodeGraphPtr, const std::string&, const std::string&, const std::string&,
             bool, const std::string&, const std::string& )) & PyBindDocument::old_addNodeDefFromGraph)
         .def("getNodeDef", &mx::Document::getNodeDef)

From 5ac34e52b6f8686d36ea964cadceb094c4015ac7 Mon Sep 17 00:00:00 2001
From: Bernard Kwok <kwokcb@gmail.com>
Date: Sun, 7 Sep 2025 10:34:01 -0400
Subject: [PATCH 3/3] Add doc for DefinitionsOptions arg on
 addNodeDefFromGraph().

---
 source/MaterialXCore/Document.h | 1 +
 1 file changed, 1 insertion(+)

diff --git a/source/MaterialXCore/Document.h b/source/MaterialXCore/Document.h
index a385499c5a..8dc01b3cff 100644
--- a/source/MaterialXCore/Document.h
+++ b/source/MaterialXCore/Document.h
@@ -363,6 +363,7 @@ class MX_CORE_API Document : public GraphElement
     /// @param newGraphName Name of new functional NodeGraph.
     /// @param nodeDefName Name of new NodeDef
     /// @param category Category of the new NodeDef
+    /// @param options Optional creation options. Default is nullptr.
     /// @return New declaration if successful.
     NodeDefPtr addNodeDefFromGraph(NodeGraphPtr nodeGraph, const string& nodeDefName,
                                    const string& category, const string& newGraphName,