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Unigine::NodeReference Class

Header: #include <UnigineNodes.h>
Inherits from: Node

A node reference is a node that refers to an external .node asset on the disk, which is obtained by exporting a node from the world. The world can contain several node references referring to the same .node file.

The .node file usually contains a pre-fabricated node (or a hierarchy of nodes) with links to all the materials, properties and physical bodies that are required for its rendering and behaviour. All changes that are made for the node reference via UnigineEditor are saved into this file. When editing the node reference via code, implement saving changes into the .node file.

Node references should be used to propagate a lot of identical objects repeated in the world: unlike regular nodes, reference nodes are loaded into the world faster because of the internal cache usage. It will also make it easier to apply the same changes to all repeated objects.

Notice
Each Node Reference has its internal copy of nodes loaded from the .node asset, therefore it is required to save changes to the asset and reload all node references. Automatic reloading is available.

Node reference supports nesting, i.e. a node reference can include other node references which is helpful for implementing complex instancing solutions.

Notice
A NodeReference itself does not have bounds and is excluded from the spatial tree.

A NodeReference instance is a Posessor of the nodes stored by it, so it is responsible for loading and deleting them. You can detach the node from the NodeReference instance to make it managed by the World.

Automatic Unpacking#

The Automatic Unpacking mode defines where the content of NodeReferences is placed in the world nodes hierarchy when it is loaded at run time (at the world startup or when a new NodeReference is created). When enabled, the content of node references is extracted to simplify hierarchy management. This is a global setting for all worlds used in your project.

Notice
  • Auto-unpacking is disabled in C++ and UnigineScript only projects by default for backward compatibility.
  • Auto-unpacking is enabled in C# projects by default.

Use World::isUnpackNodeReferences() to check if auto-unpacking is enabled in your project.

You can toggle the auto-unpacking mode by calling World::setUnpackNodeReferences() in the system logic before a world is loaded:

Source code (C++)
// AppSystemLogic.cpp
#include <UnigineWorld.h>

using namespace Unigine;

int AppSystemLogic::init() {

	// enable automatic unpacking before the world is loaded
	World::setUnpackNodeReferences(1);

	return 1;
}

The auto-unpacking mode affects the relation between the transformations of the NodeReference and the nodes stored by it.

Automatic Unpacking Disabled#

If auto-unpacking is disabled (by default in C++ / UnigineScript only projects), the content of NodeReference nodes is added to the root of the world nodes hierarchy and can be accessed only as references.

Automatic Unpacking is disabled.
Source code (C++)
// AppWorldLogic.cpp

#include <UnigineNodes.h>

using namespace Unigine;

int AppWorldLogic::init() {
	
	// create a NodeReference instance
	NodeReferencePtr nodeRef = NodeReference::create("unigine_project/nodes/node_reference_0.node");
	
	// get the reference node
	NodePtr group = nodeRef->getReference();

	// find the desired node
	NodePtr node_2 = group->getChild(group->findChild("Node_2"));

	return 1;
}

Automatic Unpacking Enabled#

When automatic unpacking of node references is enabled (by default in C# projects), the content of NodeReference nodes is extracted to simplify hierarchy management. It is done only at run time and does not affect your *.world and *.node files.

Automatic Unpacking is enabled.

The heirarchy of NodeReference's contents is attached to it as an immediate child, so you can access it in a straightforward manner:

Source code (C++)
// AppWorldLogic.cpp

#include <UnigineNodes.h>

using namespace Unigine;

int AppWorldLogic::init() {
	
	// create a NodeReference instance
	NodeReferencePtr nodeRef = NodeReference::create("nodes/node_reference_0.node");

	// get the root node of the pre-fabricated hierarchy
	NodePtr group = nodeRef->getChild(0);

	// find the desired node among all descendants
	NodePtr node_2 = nodeRef->findNode("Node_2", 1);

	return 1;
}

Node Reference Transformations#

Local transformation of the root node stored by the NodeReference is not necessarily identity, it can be displaced relative to the NodeReference position, for example.

Notice
Changing transformation of nodes stored by the NodeReference does not affect the transformation of the NodeReference itself.

If automatic unpacking of node references is enabled, the transformations of nodes are simply subject to parent-child relation. However, if automatic unpacking was disabled (i.e. the node content was added to the root of world nodes hierarchy), matrix hierarchy is used for the content of the NodeReference. Thus, when moving the NodeReference, the root node of its content also moves relatively to this NodeReference. At that, the local transformation matrix of the root reference node changes.

Notice
Changing transformation of the NodeReference resets all changes made to the local transformation of the root node stored by it only if automatic unpacking is disabled.

This relation of transformations can be destroyed by detaching the reference node from the NodeReference instance. Keep note that the unpacked detached node will remain child of the NodeReference and its tranformation matrix will still be affected by the NodeReference transformation. In this case you may need to unparent the detached node by using setParent() method.

See Also#

  • Article on Nodes that lists the main differences between the regular nodes and reference nodes
  • Article on Node Reference

Creating a Node Reference#

To create a NodeReference, you should specify a path to the existing .node file. For example, you can export a node into a .node file and then create a NodeReference by using it:

Source code (C++)
#include <UnigineEditor.h>
#include <UnigineNodes.h>
#include <UnigineObjects.h>
#include <UnigineWorld.h>

using namespace Unigine;

int AppWorldLogic::init() {

	// create a mesh
	MeshPtr mesh = Mesh::create();
	mesh->addBoxSurface("box_0", Math::vec3(1.0f));
	// create a dynamic mesh by using the mesh
	ObjectMeshDynamicPtr dynamic = ObjectMeshDynamic::create(mesh);
	// export the dynamic mesh into a .node file
	World::saveNode("unigine_project/nodes/node_reference_0.node", dynamic->getNode());
	// create a node reference
	NodeReferencePtr nodeRef = NodeReference::create("unigine_project/nodes/node_reference_0.node");

	return 1;
}

Also you can cast a Node instance to the NodeReference. However, such type casting is possible only if the Node type is NODE_REFERENCE. For example:

Source code (C++)
// AppWorldLogic.h

#include <UnigineLogic.h>
#include <UnigineStreams.h>
#include <UnigineNode.h>
#include <UnigineNodes.h>

class AppWorldLogic : public Unigine::WorldLogic {
	
public:
	AppWorldLogic();
	virtual ~AppWorldLogic();
	
	virtual int init();
	
	virtual int update();
	virtual int postUpdate();
	virtual int updatePhysics();
	
	virtual int shutdown();
	
	virtual int save(const Unigine::StreamPtr &stream);
	virtual int restore(const Unigine::StreamPtr &stream);

private:

	void nodeCast(Unigine::NodePtr node);
};
Source code (C++)
// AppWorldLogic.cpp

#include <UnigineConsole.h>
#include <UnigineObjects.h>
#include <UnigineWorld.h>

using namespace Unigine;

void AppWorldLogic::nodeCast(NodePtr node) {
	
	// check if the node is a NodeReference
	if (node->getType() == Node::NODE_REFERENCE)
	{	
		// cast the node to the NodeReference
		NodeReferencePtr nodeRef = checked_ptr_cast<NodeReference>(node);
		// set a name for the NodeReference
		nodeRef->setName("NodeReference_casted");
	}
}

int AppWorldLogic::init() {
	
	// create a NodeReference from the file
	NodeReferencePtr nodeRef_0 = NodeReference::create("unigine_project/nodes/node_reference_0.node");

	// set a name
	nodeRef_0->setName("NodeReference_0");

	// save changes into the .world file
	Console::run("world_save");
	// get the added NodeReference as a Node
	NodePtr node = World::getNodeByName("NodeReference_0");
	// cast the obtained Node to a NodeReference
	nodeCast(node);

	return 1;
}

In the result, the NodeReference_0 node will be converted to the NodeReference_casted node.

Editing a Node Reference#

Editing a NodeReference includes:

  • Changing the path to the referenced .node file.
  • Editing the node stored by the reference.

To access the node to which the NodeReference refers, use the getReference() method. To save the modified reference node to the same .node asset, use World::saveNode() method as follows:

Source code (C++)
#include <UnigineConsole.h>
#include <UnigineEditor.h>
#include <UnigineNodes.h>
#include <UnigineObjects.h>
#include <UnigineWorld.h>

using namespace Unigine;

int AppWorldLogic::init() {
	
	// create a NodeReference instance
	NodeReferencePtr nodeRef = NodeReference::create("unigine_project/nodes/node_reference_0.node");

	// set a name
	nodeRef->setName("NodeReference_0");

	// get a node stored by the reference and check if it is an ObjectMeshDynamic
	if (nodeRef->getReference()->getType() == Node::OBJECT_MESH_DYNAMIC) {
		// cast the referenced node to the ObjectMeshDynamic type
		ObjectMeshDynamicPtr dynamic = checked_ptr_cast<ObjectMeshDynamic>(nodeRef->getReference());
		// set a material
		dynamic->setMaterial("mesh_base", 0);
		// save changes on the referenced node into the .node file
		World::saveNode(nodeRef->getNodeName(), dynamic);
	}

	return 1;
}

In the result, the source .node file, to which the NodeReference refers, will be updated and the NodeReference_0 node will refer to the updated node with the material assigned. If you want all NodeReferences that refer to the modifed .node asset to update automatically, you should enable automatic reloading of NodeReferences by calling the setAutoReloadNodeReferences() method preliminarily.

Notice
Saving nodes into a *.node asset takes into account their local transformation.

NodeReference Class

Members


static NodeReferencePtr create ( const char * name ) #

Constructor. Creates a new object that references a node from a given file.

Arguments

  • const char * name - Path to a *.node file.

void setNodeName ( const char * name ) #

Sets a reference to a new *.node file.
Source code (C++)
// create an NodeReference instance
NodeReferencePtr nodeRef = NodeReference::create("unigine_project/nodes/reference_0.node");
// ...
// change a reference node
nodeRef->setNodeName("unigine_project/nodes/reference_1.node");

Arguments

  • const char * name - Path to a *.node file.

const char * getNodeName ( ) #

Returns the path to the referenced *.node file.
Source code (C++)
// create an NodeReference instance
NodeReferencePtr nodeRef = NodeReference::create("unigine_project/nodes/reference_0.node");
// ...
// return the path to the reference node
Log::message("The referenced node is: %s\n",nodeRef->getNodeName());

Return value

Path to the referenced *.node file.

Ptr<Node> getReference ( ) #

Returns the node stored by the reference. The method should be used when you need to change the referenced node. If getReference() has returned a NodeDummy instance, it means that several nodes of the same hierarchy level has been converted into the NodeReference.
Source code (C++)
// create a NodeReference instance
NodeReferencePtr nodeRef = NodeReference::create("unigine_project/nodes/single_nref.node");
// get a node stored by the reference
NodePtr node = nodeRef->getReference();
// if the node is a NodeDummy
if (node->>getType() == Node::NODE_DUMMY){
	// print the type name of each child node of the root node stored by the reference 
	for(int i = 0; i & node->getNumChildren(); i++) {
		Log::message("%d: %s\n",i,node->getChild(i)->getTypeName());
	}
}

Return value

Node instance.

static bool canBeReference ( const char * name, const Ptr<Node> & node ) #

Returns a value indicating if the hierarchy of the given node does not contain a node reference with the given name.

Arguments

  • const char * name - Node reference name.
  • const Ptr<Node> & node - Node to check.

Return value

true if the hierarchy of the given node does not contain a node reference with the given name; otherwise, false.

Ptr<Node> detachReference ( ) #

Returns the node stored by the reference and releases this node of ownership so it is no longer owned and referred to by the NodeReference. The node is managed by the World.

To remove the node do the following:

Source code (C++)
// create a new NodeReference instance
NodeReferencePtr nodeRef = NodeReference::create("unigine_project/nodes/node_reference_0.node");
// perform something
// ...
// get the node stored by the reference and release NodeReference ownership of the node
NodePtr node = nodeRef->detachReference();
// destroy the NodeReference pointer as the NodeReference doesn't refer to a node any more
nodeRef.destroy();

Return value

Root node of the internal hierarchy.

static int type ( ) #

Returns the type of the node.

Return value

NodeReference type identifier.
Last update: 2021-04-29
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