IECoreUSD::ShaderAlgo : Don't use shader type prefix for Rman

Author: danieldresser-ie

contrib/IECoreUSD/include/IECoreUSD/ShaderAlgo.h

@@ -54,6 +54,9 @@ namespace ShaderAlgo
 {
 
 /// Write ShaderNetwork to USD, placing the shaders under the Prim `shaderContainer`
+IECOREUSD_API pxr::UsdShadeOutput writeShaderNetwork( const IECoreScene::ShaderNetwork *shaderNetwork, pxr::UsdPrim shaderContainer, const std::string &shaderNetworkType );
+
+// \todo : When we can break binary compatibility, this should replaced by providing a default empty value to the last argument of the function above.
 IECOREUSD_API pxr::UsdShadeOutput writeShaderNetwork( const IECoreScene::ShaderNetwork *shaderNetwork, pxr::UsdPrim shaderContainer );
 
 /// Reads a ShaderNetwork from a material output, typically obtained from `UsdShadeMaterial::GetOutput()`.
@@ -65,6 +68,8 @@ bool canReadShaderNetwork( const pxr::UsdShadeOutput &output );
 
 #if PXR_VERSION >= 2111
 /// Writes a UsdLuxLight from a shader network.
+// TODO - if adding shaderNetworkType to writeShaderNetwork is actually the right approach, then it should
+// probably be done here too.
 IECOREUSD_API void writeLight( const IECoreScene::ShaderNetwork *shaderNetwork, pxr::UsdPrim prim );
 /// Reads a ShaderNetwork from a light.
 IECOREUSD_API IECoreScene::ShaderNetworkPtr readLight( const pxr::UsdLuxLightAPI &light );

contrib/IECoreUSD/src/IECoreUSD/ShaderAlgo.cpp

@@ -302,22 +302,40 @@ IECoreScene::ConstShaderNetworkPtr adaptShaderNetworkForWriting( const IECoreSce
 	return result;
 }
 
-pxr::UsdShadeConnectableAPI createShaderPrim( const IECoreScene::Shader *shader, const pxr::UsdStagePtr &stage, const pxr::SdfPath &path )
+pxr::UsdShadeConnectableAPI createShaderPrim( const IECoreScene::Shader *shader, const pxr::UsdStagePtr &stage, const pxr::SdfPath &path, const std::string &shaderNetworkType )
 {
 	pxr::UsdShadeShader usdShader = pxr::UsdShadeShader::Define( stage, path );
 	if( !usdShader )
 	{
 		throw IECore::Exception( "Could not create shader at " + path.GetAsString() );
 	}
+
 	const std::string type = shader->getType();
+
+	bool exportTypePrefixes = false;
+
+	if( shaderNetworkType == "arnold" )
+	{
+		exportTypePrefixes = true;
+	}
+	else if( shaderNetworkType != "ri" )
+	{
+		// \todo : This is currently here just for backwards compatibility. In the long run
+		// we should probably remove this, and only use shader type prefixes for Arnold, which requires them.
+		exportTypePrefixes = true;
+	}
+
 	std::string typePrefix;
-	size_t typeColonPos = type.find( ":" );
-	if( typeColonPos != std::string::npos )
+	if( exportTypePrefixes )
 	{
-		typePrefix = type.substr( 0, typeColonPos ) + ":";
-		if( typePrefix == "ai:" )
+		size_t typeColonPos = type.find( ":" );
+		if( typeColonPos != std::string::npos )
 		{
-			typePrefix = "arnold:";
+			typePrefix = type.substr( 0, typeColonPos ) + ":";
+			if( typePrefix == "ai:" )
+			{
+				typePrefix = "arnold:";
+			}
 		}
 	}
 	usdShader.SetShaderId( pxr::TfToken( typePrefix + shader->getName() ) );
@@ -404,6 +422,11 @@ void writeShaderConnections( const IECoreScene::ShaderNetwork *shaderNetwork, co
 } // namespace
 
 pxr::UsdShadeOutput IECoreUSD::ShaderAlgo::writeShaderNetwork( const IECoreScene::ShaderNetwork *shaderNetwork, pxr::UsdPrim shaderContainer )
+{
+	return writeShaderNetwork( shaderNetwork, shaderContainer, "" );
+}
+
+pxr::UsdShadeOutput IECoreUSD::ShaderAlgo::writeShaderNetwork( const IECoreScene::ShaderNetwork *shaderNetwork, pxr::UsdPrim shaderContainer, const std::string &shaderNetworkType )
 {
 	IECoreScene::ConstShaderNetworkPtr adaptedNetwork = adaptShaderNetworkForWriting( shaderNetwork );
 	shaderNetwork = adaptedNetwork.get();
@@ -423,7 +446,7 @@ pxr::UsdShadeOutput IECoreUSD::ShaderAlgo::writeShaderNetwork( const IECoreScene
 	for( const auto &shader : shaderNetwork->shaders() )
 	{
 		const pxr::SdfPath usdShaderPath = shaderContainer.GetPath().AppendChild( pxr::TfToken( pxr::TfMakeValidIdentifier( shader.first.string() ) ) );
-		pxr::UsdShadeConnectableAPI usdShader = createShaderPrim( shader.second.get(), shaderContainer.GetStage(), usdShaderPath );
+		pxr::UsdShadeConnectableAPI usdShader = createShaderPrim( shader.second.get(), shaderContainer.GetStage(), usdShaderPath, shaderNetworkType );
 		writeShaderParameterValues( shader.second.get(), usdShader );
 		usdShaders[shader.first] = usdShader;
 
@@ -559,7 +582,7 @@ void IECoreUSD::ShaderAlgo::writeLight( const IECoreScene::ShaderNetwork *shader
 			continue;
 		}
 		const pxr::SdfPath usdShaderPath = prim.GetPath().AppendChild( pxr::TfToken( pxr::TfMakeValidIdentifier( shader.first.string() ) ) );
-		pxr::UsdShadeConnectableAPI usdShader = createShaderPrim( shader.second.get(), prim.GetStage(), usdShaderPath );
+		pxr::UsdShadeConnectableAPI usdShader = createShaderPrim( shader.second.get(), prim.GetStage(), usdShaderPath, "" );
 		writeShaderParameterValues( shader.second.get(), usdShader );
 		usdShaders[shader.first] = usdShader;
 	}

contrib/IECoreUSD/src/IECoreUSD/USDScene.cpp

@@ -500,7 +500,16 @@ void populateMaterial( pxr::UsdShadeMaterial &mat, const boost::container::flat_
 
 		std::string shaderContainerName = boost::replace_all_copy( output.GetString(), ":", "_" ) + "_shaders";
 		pxr::UsdGeomScope shaderContainer = pxr::UsdGeomScope::Define( mat.GetPrim().GetStage(), mat.GetPath().AppendChild( pxr::TfToken( shaderContainerName ) ) );
-		pxr::UsdShadeOutput networkOut = ShaderAlgo::writeShaderNetwork( shaderNetwork.get(), shaderContainer.GetPrim() );
+
+		std::string outputString = output.GetString();
+		size_t outputColonPos = outputString.find( ":" );
+		std::string shaderNetworkType = "";
+		if( outputColonPos != std::string::npos )
+		{
+			shaderNetworkType = outputString.substr( 0, outputColonPos );
+		}
+
+		pxr::UsdShadeOutput networkOut = ShaderAlgo::writeShaderNetwork( shaderNetwork.get(), shaderContainer.GetPrim(), shaderNetworkType );
 
 		if( networkOut.GetPrim().IsValid() )
 		{