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Unigine::WorldTrigger Class

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

World triggers trigger events when any nodes (colliders or not) get inside or outside of them. The trigger can detect a node of any type by its bounding box.

You can either specify a list of nodes, for which the event handlers will be executed, or let the trigger react to all nodes (default behavior). In the latter case, the list of target nodes should be empty. There can be also specified a list of nodes that are skipped by the trigger and are free to pass unnoticed.

The handler function of World Trigger is actually executed only when the next engine function is called: that is, before updatePhysics() (in the current frame) or before update() (in the next frame) — whatever comes first.

Notice
If you have moved some nodes and want to execute event handlers based on changed positions in the same frame, you need to call World::updateSpatial() first.

Example#

The example below allows creating a line of boxes moving in and out of the World Trigger area and triggering the events. Getting inside the World Trigger enables emission for the boxes, and getting out of it disables the emission.

Source code (C++)
/* .. */
#include "AppWorldLogic.h"
#include <UnigineObjects.h>
#include <UnigineGame.h>
#include <UnigineVisualizer.h>

using namespace Unigine;

using namespace Math;

WorldTriggerPtr trigger;

const int MAX_OBJECTS = 10;
Vector<ObjectMeshStaticPtr> objects;

static void set_state(const NodePtr& node, const char* name, int value)
{
	ObjectPtr object = checked_ptr_cast<Object>(node);
	if (object.get() == NULL)
		return;

	for (int i = 0; i < object->getNumSurfaces(); i++)
	{
		MaterialPtr material = object->getMaterialInherit(i);
		if (material.get() == NULL)
			continue;
		int id = material->findState(name);
		if (id != -1)
			material->setState(id, value);
	}
}

static void trigger_enter(const NodePtr &node)
{
	set_state(node, "emission", 1);
}

static void trigger_leave(const NodePtr &node)
{
	set_state(node, "emission", 0);
}

int AppWorldLogic::init()
{

	// create trigger
	trigger = WorldTrigger::create(vec3(3.0f));
	trigger->getEventEnter().connect(&trigger_enter);
	trigger->getEventLeave().connect(&trigger_leave);

	// create objects
	for (int i = 0; i < MAX_OBJECTS; i++)
	{
		ObjectMeshStaticPtr mesh = ObjectMeshStatic::create("cbox.mesh");
		mesh->setTriggerInteractionEnabled(true);
		mesh->setMaterialParameterFloat4("albedo_color", vec4(1.0f, 0.0f, 0.0f, 1.0f), 0);
		objects.append(mesh);
	}

	// enable the visualizer
	Visualizer::setEnabled(true);

	return 1;
}

int AppWorldLogic::update()
{

	trigger->renderVisualizer();
	float time = Game::getTime();

	float hsize = objects.size() / 2.0f;

	for (int i = 0; i < objects.size(); i++)
	{
		float x = Math::sin(time) * hsize - hsize + i;
		objects[i]->setWorldTransform(translate(Vec3(x, -x, 0.0f)));
	}

	return 1;
}

int AppWorldLogic::shutdown()
{

	objects.clear();

	return 1;
}

See Also#

  • A video tutorial on How To Use World Triggers to Detect Nodes by Their Bounds
  • An article on Event Handling
  • A C++ API sample located in the <UnigineSDK>/source/samples/Api/Nodes/WorldTrigger folder
  • A C# API sample located in the <UnigineSDK>/source/csharp/samples/Api/Nodes/WorldTrigger folder
  • A set of UnigineScript API samples located in the <UnigineSDK>/data/samples/worlds/ folder:
    • trigger_00
    • trigger_01
    • trigger_02

WorldTrigger Class

Members

getNumNodes() const#

Returns the current number of nodes contained in the world trigger.

Return value

Current

Event<const Ptr<Node> &> getEventLeave() const#

event triggered when a node leaves the world trigger. You can subscribe to events via connect()  and unsubscribe via disconnect(). You can also use EventConnection  and EventConnections  classes for convenience (see examples below).

Usage Example

Source code (C++)
// implement the Leave event handler
void leave_event_handler(const Ptr<Node> & node)
{
	Log::message("\Handling Leave event\n");
}


//////////////////////////////////////////////////////////////////////////////
//  1. Multiple subscriptions can be linked to an instance of the EventConnections 
//  class that you can use later to remove all these subscriptions at once
//////////////////////////////////////////////////////////////////////////////

// create an instance of the EventConnections class
EventConnections leave_event_connections;

// link to this instance when subscribing for an event (subscription for various events can be linked)
worldtrigger->getEventLeave().connect(leave_event_connections, leave_event_handler);

// other subscriptions are also linked to this EventConnections instance 
// (e.g. you can subscribe using lambdas)
worldtrigger->getEventLeave().connect(leave_event_connections, [](const Ptr<Node> & node) { 
		Log::message("\Handling Leave event (lambda).\n");
	}
);

// ...

// later all of these linked subscriptions can be removed with a single line
leave_event_connections.disconnectAll();

//////////////////////////////////////////////////////////////////////////////
//  2. You can subscribe and unsubscribe via an instance of the EventConnection 
//  class. And toggle this particular connection off and on, when necessary.
//////////////////////////////////////////////////////////////////////////////

// create an instance of the EventConnection class
EventConnection leave_event_connection;

// subscribe for the Leave event with a handler function keeping the connection
worldtrigger->getEventLeave().connect(leave_event_connection, leave_event_handler);

// ...

// you can temporarily disable a particular event connection to perform certain actions
leave_event_connection.setEnabled(false);

// ... actions to be performed

// and enable it back when necessary
leave_event_connection.setEnabled(true);

// ...

// remove subscription for the Leave event via the connection
leave_event_connection.disconnect();

//////////////////////////////////////////////////////////////////////////////
//  3. You can add EventConnection/EventConnections instance as a member of the
//  class that handles the event. In this case all linked subscriptions will be 
//  automatically removed when class destructor is called
//////////////////////////////////////////////////////////////////////////////

// Class handling the event
class SomeClass
{
public:
	// instance of the EventConnections class as a class member
	EventConnections e_connections;

	// A Leave event handler implemented as a class member
	void event_handler(const Ptr<Node> & node)
	{
		Log::message("\Handling Leave event\n");
		// ...
	}
};

SomeClass *sc = new SomeClass();

// ...

// specify a class instance in case a handler method belongs to some class
worldtrigger->getEventLeave().connect(sc->e_connections, sc, &SomeClass::event_handler);

// ...

// handler class instance is deleted with all its subscriptions removed automatically
delete sc;

//////////////////////////////////////////////////////////////////////////////
//  4. You can subscribe and unsubscribe via the handler function directly
//////////////////////////////////////////////////////////////////////////////

// subscribe for the Leave event with a handler function
worldtrigger->getEventLeave().connect(leave_event_handler);


// remove subscription for the Leave event later by the handler function
worldtrigger->getEventLeave().disconnect(leave_event_handler);


//////////////////////////////////////////////////////////////////////////////
//   5. Subscribe to an event saving an ID and unsubscribe later by this ID
//////////////////////////////////////////////////////////////////////////////

// define a connection ID to be used to unsubscribe later
EventConnectionId leave_handler_id;

// subscribe for the Leave event with a lambda handler function and keeping connection ID
leave_handler_id = worldtrigger->getEventLeave().connect([](const Ptr<Node> & node) { 
		Log::message("\Handling Leave event (lambda).\n");
	}
);

// remove the subscription later using the ID
worldtrigger->getEventLeave().disconnect(leave_handler_id);


//////////////////////////////////////////////////////////////////////////////
//   6. Ignoring all Leave events when necessary
//////////////////////////////////////////////////////////////////////////////

// you can temporarily disable the event to perform certain actions without triggering it
worldtrigger->getEventLeave().setEnabled(false);

// ... actions to be performed

// and enable it back when necessary
worldtrigger->getEventLeave().setEnabled(true);
Notice
For more details see the Event Handling article.
The event handler signature is as follows: myhandler(const Ptr<Node> & node)

Return value

Current

Event<const Ptr<Node> &> getEventEnter() const#

event triggered when a node enters the world trigger. You can subscribe to events via connect()  and unsubscribe via disconnect(). You can also use EventConnection  and EventConnections  classes for convenience (see examples below).

Usage Example

Source code (C++)
// implement the Enter event handler
void enter_event_handler(const Ptr<Node> & node)
{
	Log::message("\Handling Enter event\n");
}


//////////////////////////////////////////////////////////////////////////////
//  1. Multiple subscriptions can be linked to an instance of the EventConnections 
//  class that you can use later to remove all these subscriptions at once
//////////////////////////////////////////////////////////////////////////////

// create an instance of the EventConnections class
EventConnections enter_event_connections;

// link to this instance when subscribing for an event (subscription for various events can be linked)
worldtrigger->getEventEnter().connect(enter_event_connections, enter_event_handler);

// other subscriptions are also linked to this EventConnections instance 
// (e.g. you can subscribe using lambdas)
worldtrigger->getEventEnter().connect(enter_event_connections, [](const Ptr<Node> & node) { 
		Log::message("\Handling Enter event (lambda).\n");
	}
);

// ...

// later all of these linked subscriptions can be removed with a single line
enter_event_connections.disconnectAll();

//////////////////////////////////////////////////////////////////////////////
//  2. You can subscribe and unsubscribe via an instance of the EventConnection 
//  class. And toggle this particular connection off and on, when necessary.
//////////////////////////////////////////////////////////////////////////////

// create an instance of the EventConnection class
EventConnection enter_event_connection;

// subscribe for the Enter event with a handler function keeping the connection
worldtrigger->getEventEnter().connect(enter_event_connection, enter_event_handler);

// ...

// you can temporarily disable a particular event connection to perform certain actions
enter_event_connection.setEnabled(false);

// ... actions to be performed

// and enable it back when necessary
enter_event_connection.setEnabled(true);

// ...

// remove subscription for the Enter event via the connection
enter_event_connection.disconnect();

//////////////////////////////////////////////////////////////////////////////
//  3. You can add EventConnection/EventConnections instance as a member of the
//  class that handles the event. In this case all linked subscriptions will be 
//  automatically removed when class destructor is called
//////////////////////////////////////////////////////////////////////////////

// Class handling the event
class SomeClass
{
public:
	// instance of the EventConnections class as a class member
	EventConnections e_connections;

	// A Enter event handler implemented as a class member
	void event_handler(const Ptr<Node> & node)
	{
		Log::message("\Handling Enter event\n");
		// ...
	}
};

SomeClass *sc = new SomeClass();

// ...

// specify a class instance in case a handler method belongs to some class
worldtrigger->getEventEnter().connect(sc->e_connections, sc, &SomeClass::event_handler);

// ...

// handler class instance is deleted with all its subscriptions removed automatically
delete sc;

//////////////////////////////////////////////////////////////////////////////
//  4. You can subscribe and unsubscribe via the handler function directly
//////////////////////////////////////////////////////////////////////////////

// subscribe for the Enter event with a handler function
worldtrigger->getEventEnter().connect(enter_event_handler);


// remove subscription for the Enter event later by the handler function
worldtrigger->getEventEnter().disconnect(enter_event_handler);


//////////////////////////////////////////////////////////////////////////////
//   5. Subscribe to an event saving an ID and unsubscribe later by this ID
//////////////////////////////////////////////////////////////////////////////

// define a connection ID to be used to unsubscribe later
EventConnectionId enter_handler_id;

// subscribe for the Enter event with a lambda handler function and keeping connection ID
enter_handler_id = worldtrigger->getEventEnter().connect([](const Ptr<Node> & node) { 
		Log::message("\Handling Enter event (lambda).\n");
	}
);

// remove the subscription later using the ID
worldtrigger->getEventEnter().disconnect(enter_handler_id);


//////////////////////////////////////////////////////////////////////////////
//   6. Ignoring all Enter events when necessary
//////////////////////////////////////////////////////////////////////////////

// you can temporarily disable the event to perform certain actions without triggering it
worldtrigger->getEventEnter().setEnabled(false);

// ... actions to be performed

// and enable it back when necessary
worldtrigger->getEventEnter().setEnabled(true);
Notice
For more details see the Event Handling article.
The event handler signature is as follows: myhandler(const Ptr<Node> & node)

Return value

Current

static WorldTriggerPtr create ( const Math::vec3 & size ) #

Constructor. Creates a new world trigger with given dimensions.

Arguments

  • const Math::vec3 & size - Dimensions of the new world trigger. If negative values are provided, 0 will be used instead of them.

void setEnterCallbackName ( const char * name ) #

Sets a name of a handler function to be executed when nodes are entering the world trigger.

Arguments

  • const char * name - World script function name.

const char * getEnterCallbackName ( ) const#

Returns the name of handler function to be executed on entering the world trigger.

Return value

World script function name.

void setExcludeNodes ( const Set<Ptr<Node>> & nodes ) #

Sets a list of excluded nodes, on which the world trigger will not react.

Arguments

  • const Set<Ptr<Node>> & nodes - Exclude nodes vector.

Set<Ptr<Node>> getExcludeNodes ( ) const#

Returns the current list of excluded nodes, on which the world trigger does not react.

Arguments

    void setExcludeTypes ( const Set<int> & types ) #

    Sets a list of excluded node types, on which the world trigger will not react.

    Arguments

    • const Set<int> & types - Exclude node types vector.

    Set<int> getExcludeTypes ( ) const#

    Returns the current list of excluded node types, on which the world trigger does not react.

    Arguments

      void setLeaveCallbackName ( const char * name ) #

      Sets a handler function to be executed when nodes are leaving the world trigger.

      Arguments

      • const char * name - World script function name.

      const char * getLeaveCallbackName ( ) const#

      Returns the name of the handler function name to be executed on leaving the world trigger.

      Return value

      World script function name.

      Ptr<Node> getNode ( int num ) const#

      Returns a specified node contained in the world trigger.
      Source code (C++)
      #include <UnigineWorlds.h>
      
      #include <UnigineInput.h>
      
      using namespace Unigine;
      
      WorldTriggerPtr trigger;
      
      int AppWorldLogic::init()
      {
      
      	// create a world trigger node
      	trigger = WorldTrigger::create(Math::vec3(3.0f));
      
      	return 1;
      }
      
      int AppWorldLogic::update()
      {
      	// press the i key to get the info about nodes inside the trigger
      	if (trigger && Input::isKeyDown(Input::KEY_I))
      	{
      		//get the number of nodes inside the trigger
      		int numNodes = trigger->getNumNodes();
      		Log::message("The number of nodes inside the trigger is %i \n", numNodes);
      
      		//loop through all nodes to print their names and types
      		for (int i = 0; i < numNodes; i++)
      		{
      			NodePtr node = trigger->getNode(i);
      			Log::message("The type of the %f node is %f \n", node->getName(), node->getType());
      		}
      	}
      	return 1;
      }

      Arguments

      • int num - Node number in range from 0 to the total number of nodes.

      Return value

      Node pointer.

      Vector<Ptr<Node>> getNodes ( ) const#

      Gets nodes contained in the trigger.

      Arguments

        int getNumNodes ( ) const#

        Returns the number of nodes contained in the world trigger.

        Return value

        Number of nodes contained in the trigger.

        void setSize ( const Math::vec3 & size ) #

        Updates the current dimensions of the world trigger. The minimum size is vec3(0,0,0).

        Arguments

        • const Math::vec3 & size - Dimensions of the world trigger. If negative values are provided, 0 will be used instead of them.

        Math::vec3 getSize ( ) const#

        Returns the current dimensions of the world trigger.

        Return value

        Current dimensions of the world trigger.

        void setTargetNodes ( const Set<Ptr<Node>> & nodes ) #

        Sets a list of target nodes, which will fire callbacks. If this list is empty, all nodes fire callbacks.

        Arguments

        • const Set<Ptr<Node>> & nodes - Target nodes vector.

        Set<Ptr<Node>> getTargetNodes ( ) const#

        Returns the current list of target nodes, which fire callbacks. If this list is empty, all nodes fire callbacks.

        Arguments

          void setTargetTypes ( const Set<int> & types ) #

          Sets a list of target node types, which will fire callbacks. If this list is empty, all nodes fire callbacks.

          Arguments

          • const Set<int> & types - Target node types vector.

          Set<int> getTargetTypes ( ) const#

          Returns the current list of target node types, which fire callbacks. If this list is empty, all nodes fire callbacks.

          Arguments

            void setTouch ( bool touch ) #

            Sets a touch mode for the trigger. With this mode on, the trigger will react to the node by partial contact. When set to off, the trigger reacts only if the whole bounding sphere/box gets inside or outside of it. The default is 0.

            Arguments

            • bool touch - Touch mode flag: true to enable the touch mode, false to disable it.

            bool isTouch ( ) const#

            Returns a value indicating if a touch mode is enabled for the trigger. With this mode on, the trigger will react to the node by partial contact. When set to off, the trigger reacts only if the whole bounding sphere/box gets inside or outside of it.

            Return value

            true if the touch mode is enabled; otherwise, false.

            static int type ( ) #

            Returns the type of the node.

            Return value

            World type identifier.
            Last update: 2023-12-22
            Build: ()