From 3537f7b58819e8b091853d42be073dee0ccf209a Mon Sep 17 00:00:00 2001
From: Jonathan Stone <jstone@lucasfilm.com>
Date: Wed, 6 Dec 2017 18:41:51 -0800
Subject: [PATCH] Add a validation rule for shader references to non-shader
 nodedefs

---
 source/MaterialXCore/Definition.cpp |  5 ++++-
 source/MaterialXCore/Definition.h   |  3 +++
 source/MaterialXCore/Material.cpp   | 14 +++++++++++++-
 source/MaterialXCore/Material.h     | 10 +++++++++-
 4 files changed, 29 insertions(+), 3 deletions(-)

diff --git a/source/MaterialXCore/Definition.cpp b/source/MaterialXCore/Definition.cpp
index 7a1f2d5d52..b130f086aa 100644
--- a/source/MaterialXCore/Definition.cpp
+++ b/source/MaterialXCore/Definition.cpp
@@ -3,13 +3,16 @@
 // All rights reserved.  See LICENSE.txt for license.
 //
 
-#include <MaterialXCore/Node.h>
+#include <MaterialXCore/Definition.h>
 
 #include <MaterialXCore/Document.h>
 
 namespace MaterialX
 {
 
+const string COLOR_SEMANTIC = "color";
+const string SHADER_SEMANTIC = "shader";
+
 const string NodeDef::NODE_ATTRIBUTE = "node";
 const string TypeDef::SEMANTIC_ATTRIBUTE = "semantic";
 const string TypeDef::CONTEXT_ATTRIBUTE = "context";
diff --git a/source/MaterialXCore/Definition.h b/source/MaterialXCore/Definition.h
index c2d42cebaf..87446c9904 100644
--- a/source/MaterialXCore/Definition.h
+++ b/source/MaterialXCore/Definition.h
@@ -16,6 +16,9 @@
 namespace MaterialX
 {
 
+extern const string COLOR_SEMANTIC;
+extern const string SHADER_SEMANTIC;
+
 /// A shared pointer to a NodeDef
 using NodeDefPtr = shared_ptr<class NodeDef>;
 /// A shared pointer to a const NodeDef
diff --git a/source/MaterialXCore/Material.cpp b/source/MaterialXCore/Material.cpp
index c3e9537b7c..09a2d5f58d 100644
--- a/source/MaterialXCore/Material.cpp
+++ b/source/MaterialXCore/Material.cpp
@@ -189,7 +189,7 @@ OutputPtr BindInput::getConnectedOutput() const
 // ShaderRef methods
 //
 
-NodeDefPtr ShaderRef::getNodeDef()
+NodeDefPtr ShaderRef::getNodeDef() const
 {
     if (hasNodeDefString())
     {
@@ -203,6 +203,18 @@ NodeDefPtr ShaderRef::getNodeDef()
     return NodeDefPtr();
 }
 
+bool ShaderRef::validate(string * message) const
+{
+    bool res = true;
+    NodeDefPtr nodeDef = getNodeDef();
+    TypeDefPtr typeDef = nodeDef ? getDocument()->getTypeDef(nodeDef->getType()) : TypeDefPtr();
+    if (typeDef)
+    {
+        validateRequire(typeDef->getSemantic() == SHADER_SEMANTIC, res, message, "Shader reference to a non-shader nodedef");
+    }
+    return Element::validate(message) && res;
+}
+
 //
 // Override methods
 //
diff --git a/source/MaterialXCore/Material.h b/source/MaterialXCore/Material.h
index 207465833c..a7b6b27edd 100644
--- a/source/MaterialXCore/Material.h
+++ b/source/MaterialXCore/Material.h
@@ -486,7 +486,7 @@ class ShaderRef : public Element
     /// @{
 
     /// Return the NodeDef, if any, that this element references.
-    NodeDefPtr getNodeDef();
+    NodeDefPtr getNodeDef() const;
 
     /// @}
     /// @name Output References
@@ -508,6 +508,14 @@ class ShaderRef : public Element
     }
 
     /// @}
+    /// @name Validation
+    /// @{
+
+    /// Validate that the given element tree, including all descendants, is
+    /// consistent with the MaterialX specification.
+    bool validate(string* message = nullptr) const override;
+
+    /// @}
 
   public:
     static const string CATEGORY;