Fixed disabled Shader pass-through bug.

We were overwriting the handle of the shader every time we accessed it, and the handle was being based on the node passed to shaderHandle(). We now never overwrite a handle once it has been generated, and also base the handle on the shader itself rather than the node it was computed for. When we do GafferHQ#335, we'll now be able to extract a useful label from the shader to use as part of the handle.

python/GafferRenderManTest/RenderManShaderTest.py

@@ -1003,6 +1003,48 @@ def testCoshaderTypeAnnotations( self ) :
 		self.assertFalse( shaderNode["parameters"]["coshaderArrayParameterType2"]["in1"].acceptsInput( coshaderNode["out"] ) )
 		self.assertFalse( shaderNode["parameters"]["coshaderArrayParameterType2"]["in1"].acceptsInput( coshaderType1Node["out"] ) )
 		self.assertTrue( shaderNode["parameters"]["coshaderArrayParameterType2"]["in1"].acceptsInput( coshaderType2Node["out"] ) )
+
+	def testSplitCoshaderPassThrough( self ) :
+
+		#   C ----S      S is connected to C both directly
+		#   |     |      and as a pass-through of the disabled
+		#   D ----       node D.
+		#
+
+		shader = self.compileShader( os.path.dirname( __file__ ) + "/shaders/coshaderArrayParameters.sl" )
+		S = GafferRenderMan.RenderManShader()
+		S.loadShader( shader )
+
+		passThroughCoshader = self.compileShader( os.path.dirname( __file__ ) + "/shaders/coshaderWithPassThrough.sl" )
+		D = GafferRenderMan.RenderManShader()
+		D.loadShader( passThroughCoshader )
 
+		coshader = self.compileShader( os.path.dirname( __file__ ) + "/shaders/coshader.sl" )
+		C = GafferRenderMan.RenderManShader()
+		C.loadShader( coshader )
+
+		S["parameters"]["fixedShaderArray"][0].setInput( C["out"] )
+		S["parameters"]["fixedShaderArray"][1].setInput( D["out"] )
+		D["parameters"]["aColorIWillTint"].setInput( C["out"] )
+
+		h = S.stateHash()
+		s = S.state()
+
+		self.assertEqual( len( s ), 3 )
+		self.assertEqual( s[2].parameters["fixedShaderArray"], IECore.StringVectorData( [ s[0].parameters["__handle"].value, s[1].parameters["__handle"].value, "", "" ] ) )
+		self.assertEqual( s[0].name, coshader )
+		self.assertEqual( s[1].parameters["aColorIWillTint"], s[0].parameters["__handle"] )
+		self.assertEqual( s[1].name, passThroughCoshader )
+
+		D["enabled"].setValue( False )
+
+		self.assertNotEqual( S.stateHash(), h )
+
+		s = S.state()
+
+		self.assertEqual( len( s ), 2 )
+		self.assertEqual( s[1].parameters["fixedShaderArray"], IECore.StringVectorData( [ s[0].parameters["__handle"].value, s[0].parameters["__handle"].value, "", "" ] ) )
+		self.assertEqual( s[0].name, coshader )
+
 if __name__ == "__main__":
 	unittest.main()

src/GafferScene/Shader.cpp

@@ -284,9 +284,13 @@ const std::string &Shader::NetworkBuilder::shaderHandle( const Shader *shaderNod
 		return emptyString;
 	}
 
-	s->setType( "shader" );
-	IECore::StringDataPtr handleData = new IECore::StringData( boost::lexical_cast<std::string>( shaderNode ) );
-	s->parameters()["__handle"] = handleData;
+	IECore::StringDataPtr handleData = s->parametersData()->member<IECore::StringData>( "__handle" );
+	if( !handleData )
+	{
+		s->setType( "shader" );
+		handleData = new IECore::StringData( boost::lexical_cast<std::string>( s ) );
+		s->parameters()["__handle"] = handleData;
+	}
 	return handleData->readable();
 }