NodesGraphModelInterface Manual

Table of Contents

• About
• Access
• Use

About

maxon::nodes::NodesGraphModelInterface is an implementation of maxon::GraphModelInterface and presents the node system (NodeSystemInterface Manual) as a graph model.

Note

If possible, one should work with the more generic maxon::GraphModelInterface, see GraphModelInterface Manual.

Access

The maxon::nodes::NodesGraphModelRef is obtained from the NodeMaterial:

• NodeMaterial::GetGraph(): Returns the node graph for the given node space ID.

See NodeMaterial Manual.

  // This example obtains the NodesGraphModelRef from the given NodeMaterial.
 
  // access node space
 
  const maxon::Id nodeSpaceID = GetActiveNodeSpaceId();
 
  if (nodeMaterial->HasSpace(nodeSpaceID) == false)
    return maxon::IllegalArgumentError(MAXON_SOURCE_LOCATION);
 
  const maxon::nodes::NodesGraphModelRef& graph = nodeMaterial->GetGraph(nodeSpaceID) iferr_return;

Use

The node graph model gives access to the stored node system:

• maxon::nodes::NodesGraphModelInterface::GetNodeSystem(): Returns the node system.
• maxon::nodes::NodesGraphModelInterface::GetMutableNodeSystem(): Returns the mutable node system.

See NodeSystemInterface Manual.

  // This example obtains the NodeSystem from the given NodeMaterial.
 
  const maxon::nodes::NodesGraphModelRef& graph  = nodeMaterial->GetGraph(nodeSpaceID) iferr_return;
  const maxon::nodes::NodeSystem&         system = graph.GetNodeSystem();

A new nodes graph can be created with the class maxon::nodes::NodesGraphModelClass().

• maxon::nodes::NodesGraphModelInterface::Init(): Initializes a new NodesGraphModelRef view for the node system.

  // This example creates a new NodesGraphModelRef.
  
  maxon::AssetRepositoryRef repository = maxon::AssetInterface::GetBuiltinRepository();
  maxon::nodes::MutableRoot root = maxon::nodes::CoreNodesNodeSystemClass().CreateNodeSystem(repository) iferr_return;
  maxon::nodes::NodeSystem  sys  = root.EndModification(maxon::NO_VALUE, maxon::nodes::NodeSystemInterface::FINALIZE_FLAGS::NONE) iferr_return;
 
  const auto filter = maxon::nodes::NodeSystemManagerInterface::FILTER::INCLUDE_INNER | maxon::nodes::NodeSystemManagerInterface::FILTER::INCLUDE_HIDDEN;
 
  const auto nodesGraphModelClass = maxon::nodes::NodesGraphModelClass();
  maxon::nodes::NodesGraphModelRef nodesGraphModel = nodesGraphModelClass.Create() iferr_return;
 
  nodesGraphModel.Init(sys, repository, filter, true) iferr_return;

A view on a node graph is a new node graph that presents only a subset of the original node graph.

• maxon::nodes::NodesGraphModelInterface::CreateView(): Returns a view on the node graph.

A node system can contain multiple children under the root node:

• maxon::nodes::NodesGraphModelInterface::AddChild(): Adds an instance of a node system or a node based on a node template as child.
• maxon::nodes::NodesGraphModelInterface::ReplaceChild(): Replaces the given child node with an instance of a node system.

  // This example obtains a node graph from a node material and inserts a new node.
 
  // get graph
  const maxon::nodes::NodesGraphModelRef& nodeGraph = nodeMaterial->GetGraph(nodeSpaceID) iferr_return;
 
  if (nodeGraph.IsReadOnly())
    return maxon::IllegalStateError(MAXON_SOURCE_LOCATION);
 
  // start a new change list if we want to apply the changes also to a different graph
  nodeGraph.StartNewChangeList() iferr_return;
 
  // start transaction
  maxon::GraphTransaction transaction = nodeGraph.BeginTransaction() iferr_return;
 
  // prepare for adding a new node
  const maxon::Id nodeAssetId { "net.maxonexample.noderenderer.usernode" };
  const maxon::AssetRepositoryRef& repository = maxon::AssetInterface::GetBuiltinRepository();
  maxon::nodes::NodeTemplate       nodeTemplate = maxon::nodes::NodesLib::LoadTemplate(repository, nodeAssetId) iferr_return;
 
  // add new node
  // leave the 'childId' parameter empty to create a UUID
  maxon::GraphNode userGraphNode = nodeGraph.AddChild(maxon::Id(), nodeTemplate) iferr_return;
  // set node name
  userGraphNode.SetValue<decltype(maxon::NODE::BASE::NAME)>("My user node"_s) iferr_return;
 
  // commit transaction
  transaction.Commit() iferr_return;
 
  // this change list contains the latest changes
  const maxon::ChangeList& list = nodeGraph.GetChangeList();

Nodes can be organized in group nodes:

• maxon::nodes::NodesGraphModelInterface::MoveToGroup(): Groups the selection of nodes of this graph into a new group node.
• maxon::nodes::NodesGraphModelInterface::Ungroup(): Dissolves the given group into its children.

Nodes are based on assets from the asset repository:

• maxon::nodes::NodesGraphModelInterface::GetLookupRepository(): Returns the asset repository to use for lookups for the node graph.
• maxon::nodes::NodesGraphModelInterface::MoveToAsset(): Makes an asset for the given node and replaces the node by a reference to that asset.

A maxon::nodes::NodeSystemManagerInterface manages a node system and its views:

• maxon::nodes::NodesGraphModelInterface::GetManager(): Returns the manager which manages this graph model.
• maxon::nodes::NodesGraphModelInterface::CreateManager(): This method should not be invoked by user code.