Premult/Unpremult : Add ignoreMissingAlpha plug

Changes.md

@@ -16,6 +16,7 @@ Improvements
   - The following parameters can now be made visible in the GraphEditor :
     - The `flake_layers` parameter of the `car_paint` shader.
     - The `data_seed`, `proc_seed`, `obj_seed`, and `face_seed` parameters of the `color_jitter` shader.
+- Premultiply / Unpremultiply : Added ignoreMissingAlpha plug.
 
 Fixes
 -----

include/GafferImage/Premultiply.h

@@ -61,6 +61,9 @@ class GAFFERIMAGE_API Premultiply : public ChannelDataProcessor
 		Gaffer::StringPlug *alphaChannelPlug();
 		const Gaffer::StringPlug *alphaChannelPlug() const;
 
+		Gaffer::BoolPlug *ignoreMissingAlphaPlug();
+		const Gaffer::BoolPlug *ignoreMissingAlphaPlug() const;
+
 		Gaffer::BoolPlug *useDeepVisibilityPlug();
 		const Gaffer::BoolPlug *useDeepVisibilityPlug() const;
 		//@}

include/GafferImage/Unpremultiply.h

@@ -60,6 +60,9 @@ class GAFFERIMAGE_API Unpremultiply : public ChannelDataProcessor
 		//@{
 		Gaffer::StringPlug *alphaChannelPlug();
 		const Gaffer::StringPlug *alphaChannelPlug() const;
+
+		Gaffer::BoolPlug *ignoreMissingAlphaPlug();
+		const Gaffer::BoolPlug *ignoreMissingAlphaPlug() const;
 		//@}
 
 		void affects( const Gaffer::Plug *input, AffectedPlugsContainer &outputs ) const override;

python/GafferImageTest/PremultiplyTest.py

@@ -64,6 +64,13 @@ def testAlphaChannel( self ) :
 		h2 = premult["out"].channelData( "R", imath.V2i( 0 ) ).hash()
 		self.assertNotEqual( h1, h2 )
 
+		premult["alphaChannel"].setValue("doesNotExist")
+		with self.assertRaisesRegex( Gaffer.ProcessException, "Channel 'doesNotExist' does not exist" ) :
+			GafferImageTest.processTiles( premult["out"] )
+
+		premult["ignoreMissingAlpha"].setValue( True )
+		self.assertImagesEqual( premult["out"], premult["in"] )
+
 	def testEnableBehaviour( self ) :
 
 		g = GafferImage.Premultiply()

python/GafferImageTest/UnpremultiplyTest.py

@@ -64,6 +64,14 @@ def testAlphaChannel( self ) :
 		h2 = unpremult["out"].channelData( "R", imath.V2i( 0 ) ).hash()
 		self.assertNotEqual( h1, h2 )
 
+		unpremult["alphaChannel"].setValue("doesNotExist")
+		with self.assertRaisesRegex( Gaffer.ProcessException, "Channel 'doesNotExist' does not exist" ) :
+			GafferImageTest.processTiles( unpremult["out"] )
+
+		unpremult["ignoreMissingAlpha"].setValue( True )
+		self.assertImagesEqual( unpremult["out"], unpremult["in"] )
+
+
 	def testEnableBehaviour( self ) :
 
 		g = GafferImage.Unpremultiply()

python/GafferImageUI/PremultiplyUI.py

@@ -65,6 +65,16 @@
 
 		],
 
+		"ignoreMissingAlpha" : [
+
+			"description",
+			"""
+			If set, this node will do nothing if the specified `alphaChannel`
+			is not found, instead of throwing an error.
+			""",
+
+		],
+
 		"useDeepVisibility" : [
 
 			"description",

python/GafferImageUI/UnpremultiplyUI.py

@@ -67,6 +67,16 @@
 
 		],
 
+		"ignoreMissingAlpha" : [
+
+			"description",
+			"""
+			If set, this node will do nothing if the specified `alphaChannel`
+			is not found, instead of throwing an error.
+			""",
+
+		],
+
 	}
 
 )

src/GafferImage/Premultiply.cpp

@@ -54,6 +54,7 @@ Premultiply::Premultiply( const std::string &name )
 {
 	storeIndexOfNextChild( g_firstPlugIndex );
 	addChild( new StringPlug( "alphaChannel", Gaffer::Plug::In, "A" ) );
+	addChild( new BoolPlug( "ignoreMissingAlpha", Gaffer::Plug::In, false ) );
 	addChild( new BoolPlug( "useDeepVisibility", Gaffer::Plug::In, false ) );
 }
 
@@ -71,16 +72,26 @@ const Gaffer::StringPlug *Premultiply::alphaChannelPlug() const
 	return getChild<StringPlug>( g_firstPlugIndex );
 }
 
-Gaffer::BoolPlug *Premultiply::useDeepVisibilityPlug()
+Gaffer::BoolPlug *Premultiply::ignoreMissingAlphaPlug()
 {
 	return getChild<BoolPlug>( g_firstPlugIndex + 1 );
 }
 
-const Gaffer::BoolPlug *Premultiply::useDeepVisibilityPlug() const
+const Gaffer::BoolPlug *Premultiply::ignoreMissingAlphaPlug() const
 {
 	return getChild<BoolPlug>( g_firstPlugIndex + 1 );
 }
 
+Gaffer::BoolPlug *Premultiply::useDeepVisibilityPlug()
+{
+	return getChild<BoolPlug>( g_firstPlugIndex + 2 );
+}
+
+const Gaffer::BoolPlug *Premultiply::useDeepVisibilityPlug() const
+{
+	return getChild<BoolPlug>( g_firstPlugIndex + 2 );
+}
+
 void Premultiply::affects( const Gaffer::Plug *input, AffectedPlugsContainer &outputs ) const
 {
 	ChannelDataProcessor::affects( input, outputs );
@@ -91,6 +102,7 @@ void Premultiply::affects( const Gaffer::Plug *input, AffectedPlugsContainer &ou
 		input == inPlug()->deepPlug() ||
 		input == inPlug()->sampleOffsetsPlug() ||
 		input == alphaChannelPlug() ||
+		input == ignoreMissingAlphaPlug() ||
 		input == useDeepVisibilityPlug()
 	)
 	{
@@ -100,29 +112,44 @@ void Premultiply::affects( const Gaffer::Plug *input, AffectedPlugsContainer &ou
 
 void Premultiply::hashChannelData( const GafferImage::ImagePlug *output, const Gaffer::Context *context, IECore::MurmurHash &h ) const
 {
-
-	ChannelDataProcessor::hashChannelData( output, context, h );
-
 	std::string alphaChannel;
 	ConstStringVectorDataPtr inChannelNamesPtr;
+	bool ignoreMissingAlpha;
 	bool useDeepVisibility;
+	bool deep;
 	{
 		ImagePlug::GlobalScope c( context );
 		alphaChannel = alphaChannelPlug()->getValue();
 		inChannelNamesPtr = inPlug()->channelNamesPlug()->getValue();
+		ignoreMissingAlpha = ignoreMissingAlphaPlug()->getValue();
 		useDeepVisibility = useDeepVisibilityPlug()->getValue();
-		inPlug()->deepPlug()->hash( h );
+		deep = inPlug()->deepPlug()->getValue();
 	}
 
-	h.append( alphaChannel == context->get<std::string>( ImagePlug::channelNameContextName ) );
+	if(
+		(!useDeepVisibility && alphaChannel == context->get<std::string>( ImagePlug::channelNameContextName ) ) ||
+		( useDeepVisibility && !deep )
+	)
+	{
+		h = inPlug()->channelDataPlug()->hash();
+		return;
+	}
 
 	const std::vector<std::string> &inChannelNames = inChannelNamesPtr->readable();
 	if ( std::find( inChannelNames.begin(), inChannelNames.end(), alphaChannel ) == inChannelNames.end() )
 	{
-		throw IECore::Exception( fmt::format( "Channel '{}' does not exist", alphaChannel ) );
+		if( ignoreMissingAlpha )
+		{
+			h = inPlug()->channelDataPlug()->hash();
+			return;
+		}
+		else
+		{
+			throw IECore::Exception( fmt::format( "Channel '{}' does not exist", alphaChannel ) );
+		}
 	}
 
-	inPlug()->channelDataPlug()->hash( h );
+	ChannelDataProcessor::hashChannelData( output, context, h );
 
 	ImagePlug::ChannelDataScope channelDataScope( context );
 	channelDataScope.setChannelName( &alphaChannel );
@@ -142,24 +169,39 @@ void Premultiply::processChannelData( const Gaffer::Context *context, const Imag
 	std::string alphaChannel;
 	ConstStringVectorDataPtr inChannelNamesPtr;
 	bool useDeepVisibility;
+	bool ignoreMissingAlpha;
 	bool deep;
 	{
 		ImagePlug::GlobalScope c( context );
 		alphaChannel = alphaChannelPlug()->getValue();
 		inChannelNamesPtr = inPlug()->channelNamesPlug()->getValue();
 		useDeepVisibility = useDeepVisibilityPlug()->getValue();
+		ignoreMissingAlpha = ignoreMissingAlphaPlug()->getValue();
 		deep = inPlug()->deepPlug()->getValue();
 	}
 
-	if( !useDeepVisibility && channel == alphaChannel )
+	if(
+		// Unless we're doing useDeepVisibility, we don't process the alpha channel
+		( !useDeepVisibility && channel == alphaChannel ) ||
+		// If it's a flat image, useDeepVisibility means don't do anything
+		// ( There is never a sample in front, so the visibility is always 100% )
+		( useDeepVisibility && !deep )
+	)
 	{
 		return;
 	}
 
 	const std::vector<std::string> &inChannelNames = inChannelNamesPtr->readable();
 	if ( std::find( inChannelNames.begin(), inChannelNames.end(), alphaChannel ) == inChannelNames.end() )
 	{
-		throw IECore::Exception( fmt::format( "Channel '{}' does not exist", alphaChannel ) );
+		if( ignoreMissingAlpha )
+		{
+			return;
+		}
+		else
+		{
+			throw IECore::Exception( fmt::format( "Channel '{}' does not exist", alphaChannel ) );
+		}
 	}
 
 	ImagePlug::ChannelDataScope channelDataScope( context );
@@ -179,13 +221,6 @@ void Premultiply::processChannelData( const Gaffer::Context *context, const Imag
 		return;
 	}
 
-	if( !deep )
-	{
-		// If it's a flat image, useDeepVisibility means don't do anything
-		// ( There is never a sample in front, so the visibility is always 100%
-		return;
-	}
-
 	channelDataScope.remove( ImagePlug::channelNameContextName );
 	ConstIntVectorDataPtr sampleOffsetsData = inPlug()->sampleOffsetsPlug()->getValue();
 

src/GafferImage/Unpremultiply.cpp

@@ -54,6 +54,7 @@ Unpremultiply::Unpremultiply( const std::string &name )
 {
 	storeIndexOfNextChild( g_firstPlugIndex );
 	addChild( new StringPlug( "alphaChannel", Gaffer::Plug::In, "A" ) );
+	addChild( new BoolPlug( "ignoreMissingAlpha", Gaffer::Plug::In, false ) );
 }
 
 Unpremultiply::~Unpremultiply()
@@ -70,13 +71,24 @@ const Gaffer::StringPlug *Unpremultiply::alphaChannelPlug() const
 	return getChild<StringPlug>( g_firstPlugIndex );
 }
 
+Gaffer::BoolPlug *Unpremultiply::ignoreMissingAlphaPlug()
+{
+	return getChild<BoolPlug>( g_firstPlugIndex + 1 );
+}
+
+const Gaffer::BoolPlug *Unpremultiply::ignoreMissingAlphaPlug() const
+{
+	return getChild<BoolPlug>( g_firstPlugIndex + 1 );
+}
+
 void Unpremultiply::affects( const Gaffer::Plug *input, AffectedPlugsContainer &outputs ) const
 {
 	ChannelDataProcessor::affects( input, outputs );
 
 	if(
 		input == inPlug()->channelDataPlug() ||
-		input == alphaChannelPlug()
+		input == alphaChannelPlug() ||
+		input == ignoreMissingAlphaPlug()
 	)
 	{
 		outputs.push_back( outPlug()->channelDataPlug() );
@@ -85,11 +97,32 @@ void Unpremultiply::affects( const Gaffer::Plug *input, AffectedPlugsContainer &
 
 void Unpremultiply::hashChannelData( const GafferImage::ImagePlug *output, const Gaffer::Context *context, IECore::MurmurHash &h ) const
 {
-	std::string alphaChannel = alphaChannelPlug()->getValue();
+	std::string alphaChannel;
+	ConstStringVectorDataPtr inChannelNamesPtr;
+	bool ignoreMissingAlpha;
 
-	ChannelDataProcessor::hashChannelData( output, context, h );
+	{
+		ImagePlug::GlobalScope c( context );
+		alphaChannel = alphaChannelPlug()->getValue();
+		inChannelNamesPtr = inPlug()->channelNamesPlug()->getValue();
+		ignoreMissingAlpha = ignoreMissingAlphaPlug()->getValue();
+	}
 
-	inPlug()->channelDataPlug()->hash( h );
+	const std::vector<std::string> &inChannelNames = inChannelNamesPtr->readable();
+	if ( std::find( inChannelNames.begin(), inChannelNames.end(), alphaChannel ) == inChannelNames.end() )
+	{
+		if( ignoreMissingAlpha )
+		{
+			h = inPlug()->channelDataPlug()->hash();
+			return;
+		}
+		else
+		{
+			throw IECore::Exception( fmt::format( "Channel '{}' does not exist", alphaChannel ) );
+		}
+	}
+
+	ChannelDataProcessor::hashChannelData( output, context, h );
 
 	ImagePlug::ChannelDataScope channelDataScope( context );
 	channelDataScope.setChannelName( &alphaChannel );
@@ -99,25 +132,33 @@ void Unpremultiply::hashChannelData( const GafferImage::ImagePlug *output, const
 
 void Unpremultiply::processChannelData( const Gaffer::Context *context, const ImagePlug *parent, const std::string &channel, FloatVectorDataPtr outData ) const
 {
-	std::string alphaChannel = alphaChannelPlug()->getValue();
+	std::string alphaChannel;
+	ConstStringVectorDataPtr inChannelNamesPtr;
+	bool ignoreMissingAlpha;
 
-	if ( channel == alphaChannel )
 	{
-		return;
+		ImagePlug::GlobalScope c( context );
+		alphaChannel = alphaChannelPlug()->getValue();
+		inChannelNamesPtr = inPlug()->channelNamesPlug()->getValue();
+		ignoreMissingAlpha = ignoreMissingAlphaPlug()->getValue();
 	}
 
-	ConstStringVectorDataPtr inChannelNamesPtr;
+	if ( channel == alphaChannel )
 	{
-		ImagePlug::GlobalScope c( context );
-		inChannelNamesPtr = inPlug()->channelNamesPlug()->getValue();
+		return;
 	}
 
 	const std::vector<std::string> &inChannelNames = inChannelNamesPtr->readable();
 	if ( std::find( inChannelNames.begin(), inChannelNames.end(), alphaChannel ) == inChannelNames.end() )
 	{
-		std::ostringstream channelError;
-		channelError << "Channel '" << alphaChannel << "' does not exist";
-		throw( IECore::Exception( channelError.str() ) );
+		if( ignoreMissingAlpha )
+		{
+			return;
+		}
+		else
+		{
+			throw IECore::Exception( fmt::format( "Channel '{}' does not exist", alphaChannel ) );
+		}
 	}
 
 	ImagePlug::ChannelDataScope channelDataScope( context );