Method update

src/IECoreScene/ShaderNetwork.cpp:712–766

		}

		void update() const
		{
			std::unique_lock<std::mutex> lock( m_updateMutex );
			if( m_dirty )
			{
				m_hash = MurmurHash();
				m_neededSubstitutions.clear();
				m_parmsNeedingSubstitution.clear();
				for( const auto &node : m_nodes )
				{
					m_hash.append( node.handle );
					node.shader->hash( m_hash );
					std::vector< InternedString > parmsNeedingSub;

					for( const auto &connection : node.inputConnections )
					{
						m_hash.append( connection.source.shader );
						m_hash.append( connection.source.name );
						m_hash.append( connection.destination.name );
					}

					for( const auto &parm : node.shader->parameters() )
					{
						bool needed = false;
						StringData *stringParm = IECore::runTimeCast< StringData >( parm.second.get() );
						StringVectorData *stringVectorParm = IECore::runTimeCast< StringVectorData >( parm.second.get() );
						if( stringParm )
						{
							needed |= stringFindSubstitutions( stringParm->readable(), m_neededSubstitutions );
						}
						if( stringVectorParm )
						{
							for( const std::string &i : stringVectorParm->readable() )
							{
								needed |= stringFindSubstitutions( i, m_neededSubstitutions );
							}
						}
						if( needed )
						{
							parmsNeedingSub.push_back( parm.first );
						}
					}

					if( parmsNeedingSub.size() )
					{
						m_parmsNeedingSubstitution[ node.handle ] = parmsNeedingSub;
					}
				}

				m_hash.append( m_output.shader );
				m_hash.append( m_output.name );

				m_dirty = false;
			}
		}

		static unsigned int g_ioVersion;