text: //////////////////////////////////////////////////////////////////////////
  //  
  //  Copyright (c) 2012, John Haddon. All rights reserved.
  //  Copyright (c) 2013, Image Engine Design Inc. All rights reserved.
  //  
  //  Redistribution and use in source and binary forms, with or without
  //  modification, are permitted provided that the following conditions are
  //  met:
  //  
  //      * Redistributions of source code must retain the above
  //        copyright notice, this list of conditions and the following
  //        disclaimer.
  //  
  //      * Redistributions in binary form must reproduce the above
  //        copyright notice, this list of conditions and the following
  //        disclaimer in the documentation and/or other materials provided with
  //        the distribution.
  //  
  //      * Neither the name of John Haddon nor the names of
  //        any other contributors to this software may be used to endorse or
  //        promote products derived from this software without specific prior
  //        written permission.
  //  
  //  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
  //  IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
  //  THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  //  PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
  //  CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
  //  EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
  //  PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
  //  PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
  //  LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
  //  NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
  //  SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  //  
  //////////////////////////////////////////////////////////////////////////
  
  #include "GafferScene/SceneProcessor.h"
  
  using namespace Gaffer;
  using namespace GafferScene;
  
  IE_CORE_DEFINERUNTIMETYPED( SceneProcessor );
  
  size_t SceneProcessor::g_firstPlugIndex = 0;
  
  SceneProcessor::SceneProcessor( const std::string &name )
  	:	SceneNode( name )
  {
  	storeIndexOfNextChild( g_firstPlugIndex );
  	addChild( new ScenePlug( "in", Gaffer::Plug::In ) );
  }
  
  SceneProcessor::~SceneProcessor()
  {
  }
  
  ScenePlug *SceneProcessor::inPlug()
  {
  	return getChild<ScenePlug>( g_firstPlugIndex );
  }
  
  const ScenePlug *SceneProcessor::inPlug() const
  {
  	return getChild<ScenePlug>( g_firstPlugIndex );
  }
  
  Plug *SceneProcessor::correspondingInput( const Plug *output )
  {
  	if ( output == outPlug() )
  	{
  		return inPlug();
  	}
  	
  	return SceneNode::correspondingInput( output );
  }
  
  const Plug *SceneProcessor::correspondingInput( const Plug *output ) const
  {
  	if ( output == outPlug() )
  	{
  		return inPlug();
  	}
  	
  	return SceneNode::correspondingInput( output );
  }
  
  void SceneProcessor::hash( const Gaffer::ValuePlug *output, const Gaffer::Context *context, IECore::MurmurHash &h ) const
  {
  	const ScenePlug *scenePlug = output->parent<ScenePlug>();
  	if( scenePlug && !enabledPlug()->getValue() )
  	{
  		// if we're hashing the output scene, and we're disabled, we need to
  		// pass through the hash from the inPlug().
  		h = inPlug()->getChild<ValuePlug>( output->getName() )->hash();
  	}
  	else
  	{
  		// if not, we can let the base class take care of everything.
  		SceneNode::hash( output, context, h );
  	}
  }
  
  void SceneProcessor::compute( Gaffer::ValuePlug *output, const Gaffer::Context *context ) const
  {
  	const ScenePlug *scenePlug = output->parent<ScenePlug>();
  	if( scenePlug && !enabledPlug()->getValue() )
  	{
  		// if we're computing the output scene, and we're disabled, we need to
  		// pass through the scene from inPlug().
  		output->setFrom( inPlug()->getChild<ValuePlug>( output->getName() ) );
  	}
  	else
  	{
  		// otherwise, we can let the base class take care of everything.
  		SceneNode::compute( output, context );
  	}
  }
  