Cycles : Added light-linking, as well as some tweaks to CyclesMeshLig…

…ht so it can participate in linking.

Changes.md

@@ -5,6 +5,7 @@ Features
 --------
 
 - DeepSlice : Added a new node for clipping out part of an image based on depth.
+- Cycles : Added support for light-linking.
 
 Improvements
 ------------

python/GafferCyclesTest/InteractiveCyclesRenderTest.py

@@ -56,16 +56,6 @@ def testAddAndRemoveOutput( self ) :
 
 		pass
 
-	@unittest.skip( "Light linking not supported" )
-	def testLightLinking( self ) :
-
-		pass
-
-	@unittest.skip( "Light linking not supported" )
-	def testHideLinkedLight( self ) :
-
-		pass
-
 	def _createConstantShader( self ) :
 
 		shader = GafferCycles.CyclesShader()

python/GafferCyclesUI/CyclesMeshLightUI.py

@@ -50,8 +50,7 @@ def __shaderMetadata( plug, name ) :
 	"description",
 	"""
 	Turns mesh primitives into Cycles mesh lights by assigning
-	an emission shader, turning off all visibility except for camera rays,
-	and adding the meshes to the default lights set.
+	an emission shader and adding the meshes to the default lights set.
 	""",
 
 	plugs = {
@@ -64,6 +63,8 @@ def __shaderMetadata( plug, name ) :
 			rays.
 			""",
 
+			"nameValuePlugPlugValueWidget:ignoreNamePlug", True,
+
 		],
 
 		"lightGroup" : [
@@ -73,6 +74,31 @@ def __shaderMetadata( plug, name ) :
 			The light group that the mesh light will contribute to.
 			""",
 
+			"nameValuePlugPlugValueWidget:ignoreNamePlug", True,
+
+		],
+
+		"emissionSamplingMethod" : [
+
+			"description",
+			"""
+			Sampling strategy for emissive surfaces.
+			""",
+
+			"nameValuePlugPlugValueWidget:ignoreNamePlug", True,
+
+		],
+
+		"emissionSamplingMethod.value" : [
+
+			"preset:None", "none",
+			"preset:Auto", "auto",
+			"preset:Front", "front",
+			"preset:Back", "back",
+			"preset:Front-Back", "front_back",
+
+			"plugValueWidget:type", "GafferUI.PresetsPlugValueWidget",
+
 		],
 
 		"parameters" : [

src/GafferCycles/CyclesMeshLight.cpp

@@ -57,27 +57,13 @@ CyclesMeshLight::CyclesMeshLight( const std::string &name )
 	:	GafferScene::FilteredSceneProcessor( name, IECore::PathMatcher::NoMatch )
 {
 
-	// CyclesAttributesNode. This hides the objects from the majority
-	// of ray types, since we don't want to add the poor sampling of the
-	// object on top of the nice sampling of the light. The only visibility
-	// option we don't turn off is camera visibility - instead we promote
-	// so the user can decide whether or not the mesh should be visible in
-	// the render.
-
 	CyclesAttributesPtr attributes = new CyclesAttributes( "__attributes" );
 	attributes->inPlug()->setInput( inPlug() );
 	attributes->filterPlug()->setInput( filterPlug() );
-	for( NameValuePlug::Iterator it( attributes->attributesPlug() ); !it.done(); ++it )
-	{
-		if( boost::ends_with( (*it)->getName().string(), "Visibility" ) && (*it)->getName() != "cameraVisibility" )
-		{
-			(*it)->enabledPlug()->setValue( true );
-			(*it)->valuePlug<BoolPlug>()->setValue( false );
-		}
-	}
-
 	addChild( attributes );
 
+	// Camera visibility
+
 	Plug *internalCameraVisibilityPlug = attributes->attributesPlug()->getChild<Plug>( "cameraVisibility" );
 	PlugPtr cameraVisibilityPlug = internalCameraVisibilityPlug->createCounterpart( "cameraVisibility", Plug::In );
 	addChild( cameraVisibilityPlug );
@@ -90,6 +76,13 @@ CyclesMeshLight::CyclesMeshLight( const std::string &name )
 	addChild( lightGroupPlug );
 	internalLightGroupPlug->setInput( lightGroupPlug );
 
+	// Emission sampling method
+
+	Plug *internalEmissionSamplingMethodPlug = attributes->attributesPlug()->getChild<Plug>( "emissionSamplingMethod" );
+	PlugPtr emissionSamplingMethodPlug = internalEmissionSamplingMethodPlug->createCounterpart( "emissionSamplingMethod", Plug::In );
+	addChild( emissionSamplingMethodPlug );
+	internalEmissionSamplingMethodPlug->setInput( emissionSamplingMethodPlug );
+
 	// Shader node. This loads the Cycles emission shader.
 
 	CyclesShaderPtr shader = new CyclesShader( "__shader" );
@@ -115,13 +108,23 @@ CyclesMeshLight::CyclesMeshLight( const std::string &name )
 	shaderAssignment->shaderPlug()->setInput( shader->outPlug() );
 	addChild( shaderAssignment );
 
+	// Set node. This adds the objects into the __lights set,
+	// so they will be output correctly to the renderer.
+
+	SetPtr set = new Set( "__set" );
+	set->inPlug()->setInput( shaderAssignment->outPlug() );
+	set->filterPlug()->setInput( filterPlug() );
+	set->namePlug()->setValue( "__lights" );
+	set->modePlug()->setValue( Set::Add );
+	addChild( set );
+
 	// Default lights Set node.
 
 	BoolPlugPtr defaultLightPlug = new BoolPlug( "defaultLight", Plug::In, true );
 	addChild( defaultLightPlug );
 
 	SetPtr defaultLightsSet = new Set( "__defaultLightsSet" );
-	defaultLightsSet->inPlug()->setInput( shaderAssignment->outPlug() );
+	defaultLightsSet->inPlug()->setInput( set->outPlug() );
 	defaultLightsSet->filterPlug()->setInput( filterPlug() );
 	defaultLightsSet->enabledPlug()->setInput( defaultLightPlug.get() );
 	defaultLightsSet->namePlug()->setValue( "defaultLights" );