TweakPlug : Specify when a fallback value is appropriate

This works around issues with CreateIfMissing mode where the fallback value would mask missing values and no tweak would be created as nothing would be considered missing.
GafferHQ · May 23, 2024 · db87ba8 · db87ba8
1 parent e535b88
commit db87ba8
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Showing 8 changed files with 31 additions and 8 deletions.
diff --git a/include/Gaffer/TweakPlug.inl b/include/Gaffer/TweakPlug.inl
@@ -93,7 +93,7 @@ bool TweakPlug::applyTweak(
 		return setDataFunctor( name, newData );
 	}
 
-	const IECore::Data *currentValue = getDataFunctor( name );
+	const IECore::Data *currentValue = getDataFunctor( name, /* fallback = */ mode != Gaffer::TweakPlug::CreateIfMissing );
 
 	if( IECore::runTimeCast<const IECore::InternedStringData>( currentValue ) )
 	{

diff --git a/python/GafferSceneTest/AttributeTweaksTest.py b/python/GafferSceneTest/AttributeTweaksTest.py
@@ -227,5 +227,28 @@ def testLinkedLightsSourceSubstitution( self ) :
 		standardAttributes["attributes"]["linkedLights"]["value"].setValue( "someLights" )
 		self.assertEqual( tweaks["out"].attributes( "/plane" )["linkedLights"], IECore.StringData( "(someLights) - unwantedLights" ) )
 
+	def testLinkedLightsCreateIfMissing( self ) :
+
+		plane = GafferScene.Plane()
+
+		planeFilter = GafferScene.PathFilter()
+		planeFilter["paths"].setValue( IECore.StringVectorData( [ "/plane" ] ) )
+
+		standardAttributes = GafferScene.StandardAttributes()
+		standardAttributes["in"].setInput( plane["out"] )
+		standardAttributes["filter"].setInput( planeFilter["out"] )
+
+		self.assertNotIn( "linkedLights", standardAttributes["out"].attributes( "/plane" ) )
+
+		tweaks = GafferScene.AttributeTweaks()
+		tweaks["in"].setInput( standardAttributes["out"] )
+		tweaks["filter"].setInput( planeFilter["out"] )
+
+		testTweak = Gaffer.TweakPlug( "linkedLights", "defaultLights" )
+		testTweak["mode"].setValue( Gaffer.TweakPlug.Mode.CreateIfMissing )
+		tweaks["tweaks"].addChild( testTweak )
+
+		self.assertEqual( tweaks["out"].attributes( "/plane" )["linkedLights"], IECore.StringData( "defaultLights" ) )
+
 if __name__ == "__main__" :
 	unittest.main()
diff --git a/src/Gaffer/ContextVariableTweaks.cpp b/src/Gaffer/ContextVariableTweaks.cpp
@@ -97,7 +97,7 @@ void ContextVariableTweaks::processContext( Context::EditableScope &context, IEC
 	IECore::ObjectVectorPtr storageVector = new ObjectVector();
 
 	tweaksPlug->applyTweaks(
-		[&context, &sourceData]( const std::string &valueName )
+		[&context, &sourceData]( const std::string &valueName, const bool fallback )
 		{
 			DataPtr value = context.context()->getAsData( valueName, nullptr );
 			sourceData = value;

diff --git a/src/Gaffer/TweakPlug.cpp b/src/Gaffer/TweakPlug.cpp
@@ -279,7 +279,7 @@ Gaffer::PlugPtr TweakPlug::createCounterpart( const std::string &name, Direction
 bool TweakPlug::applyTweak( IECore::CompoundData *parameters, MissingMode missingMode ) const
 {
 	return applyTweak(
-		[&parameters]( const std::string &valueName ) { return parameters->member( valueName ); },
+		[&parameters]( const std::string &valueName, const bool fallback ) { return parameters->member( valueName ); },
 		[&parameters]( const std::string &valueName, DataPtr newData )
 		{
 			if( newData == nullptr )

diff --git a/src/GafferScene/AttributeTweaks.cpp b/src/GafferScene/AttributeTweaks.cpp
@@ -154,10 +154,10 @@ IECore::ConstCompoundObjectPtr AttributeTweaks::computeProcessedAttributes( cons
 	}
 
 	tweaksPlug->applyTweaks(
-		[&source]( const std::string &valueName ) -> const IECore::Data *
+		[&source]( const std::string &valueName, const bool fallback ) -> const IECore::Data *
 		{
 			const Data *result = source->member<Data>( valueName );
-			if( !result && valueName == "linkedLights" )
+			if( fallback && !result && valueName == "linkedLights" )
 			{
 				/// \todo Use a registry to provide default values for
 				/// all attributes.

diff --git a/src/GafferScene/CameraTweaks.cpp b/src/GafferScene/CameraTweaks.cpp
@@ -125,7 +125,7 @@ IECore::ConstObjectPtr CameraTweaks::computeProcessedObject( const ScenePath &pa
 	tweaksPlug->applyTweaks(
 
 		// Getter
-		[&] ( const std::string &name ) {
+		[&] ( const std::string &name, const bool fallback ) {
 			if( name == "fieldOfView" )
 			{
 				virtualParameter = new FloatData( result->calculateFieldOfView()[0] );

diff --git a/src/GafferScene/OptionTweaks.cpp b/src/GafferScene/OptionTweaks.cpp
@@ -121,7 +121,7 @@ IECore::ConstCompoundObjectPtr OptionTweaks::computeProcessedGlobals(
 	result->members() = inputGlobals->members();
 
 	tweaksPlug->applyTweaks(
-		[&result]( const std::string &valueName )
+		[&result]( const std::string &valueName, const bool fallback )
 		{
 			return result->member<Data>( g_namePrefix + valueName );
 		},

diff --git a/src/GafferScene/ShaderTweaks.cpp b/src/GafferScene/ShaderTweaks.cpp
@@ -332,7 +332,7 @@ bool ShaderTweaks::applyTweaks( IECoreScene::ShaderNetwork *shaderNetwork, Tweak
 
 			if(
 				tweakPlug->applyTweak(
-					[&parameter, &modifiedShader]( const std::string &valueName )
+					[&parameter, &modifiedShader]( const std::string &valueName, const bool fallback )
 					{
 						return modifiedShader.first->second->parametersData()->member( parameter.name );
 					},