fixup! 3Delight ShaderNetworkAlgo : Translate UsdPreviewSurface to 3D…

…elight

Ensure dlPrimitiveAttribute outputs UVs in older 3Delight versions

python/IECoreDelightTest/ShaderNetworkAlgoTest.py

@@ -513,7 +513,7 @@ def testConvertUSDPrimvarReader( self ) :
 
 			reader = network.getShader( "reader" )
 			self.assertEqual( reader.name, convertedShaderType )
-			self.assertEqual( len( reader.parameters ), 2 )
+			self.assertEqual( len( reader.parameters ), 3 if convertedShaderType == "dlPrimitiveAttribute" else 2 )
 			self.assertEqual( reader.parameters["attribute_name" if convertedShaderType == "dlPrimitiveAttribute" else "name"].value, "test" )
 			self.assertEqual( reader.parameters["fallback_value" if convertedShaderType == "dlPrimitiveAttribute" else "defaultValue"].value, convertedDefault )
 

src/IECoreDelight/ShaderNetworkAlgo.cpp

@@ -398,6 +398,7 @@ Color3f blackbody( float kelvins )
 
 const InternedString g_angleParameter( "angle" );
 const InternedString g_attributeNameParameter( "attribute_name" );
+const InternedString g_attributeTypeParameter( "attribute_type" );
 const InternedString g_aParameter( "a" );
 const InternedString g_bParameter( "b" );
 const InternedString g_baseParameter( "base" );
@@ -903,6 +904,7 @@ void convertUSDShaders( ShaderNetwork *shaderNetwork )
 		else if( shader->getName() == "UsdPrimvarReader_float2" )
 		{
 			newShader = new Shader( "dlPrimitiveAttribute", "osl:surface" );
+			newShader->parameters()[g_attributeTypeParameter] = new IntData( 3 ); // UV
 			transferUSDParameter( shaderNetwork, handle, shader.get(), g_varnameParameter, newShader.get(), g_attributeNameParameter, std::string() );
 			transferUSDParameter( shaderNetwork, handle, shader.get(), g_fallbackParameter, newShader.get(), g_fallbackValueParameter, V2f( 0 ) );
 			convertVecToColor<V2f, Color3f>( newShader.get(), g_fallbackValueParameter );