Adding a Behavior

Adding a Behavior allows you to code and give a specific behavior (code, actions, things to do) to an object in the scene.

After you've created the Behaviour through the use of a game plugin, you will be able to give a Behavior to an object directly within the Maratis Editor.

Behaviors also allow to set a given number of variables to the object which has the Behavior; those variables can be then edited directly within the Maratis Editor or with the use of scripts.

In this example we will make an object rotating with the use of a Behavior.

Game Plugin

First you need to create a game plugin as shown here: How to add your own C++ code (Game Plugin tutorial)

Source code

Now you can create the MyBehavior.h and MyBehavior.cpp files which will contain the code for your Behavior.

MyBehavior.h

/////////////////////////////////////////////////////////////////////////////////////////////////////////
// GamePlugin
// MyBehavior.h
// 
// Code : Anael Seghezzi
/////////////////////////////////////////////////////////////////////////////////////////////////////////

#ifndef _MY_BEHAVIOR_H
#define _MY_BEHAVIOR_H

#include <MEngine.h>


class MyBehavior : public MBehavior
{
public:

	// constructors / destructors
	MyBehavior(MObject3d * parentObject);
	MyBehavior(MyBehavior & behavior, MObject3d * parentObject);
	~MyBehavior(void);

private:
	
	// cutom variables
	float m_rotationSpeed;
	
public:

	// destroy
	void destroy(void);

	// get new
	static MBehavior * getNew(MObject3d * parentObject);

	// get copy
	MBehavior * getCopy(MObject3d * parentObject);

	// name
	static const char * getStaticName(void){ return "MyBehavior"; }
	const char * getName(void){ return getStaticName(); }

	// variables
	unsigned int getVariablesNumber(void);
	MVariable getVariable(unsigned int id);

	// events (virtuals from MBehavior class)
	void update(void);
	void runEvent(int param){}
};

#endif

MyBehavior.cpp

/////////////////////////////////////////////////////////////////////////////////////////////////////////
// GamePlugin
// MyBehavior.cpp
// 
// Code : Anael Seghezzi
/////////////////////////////////////////////////////////////////////////////////////////////////////////

#include "MyBehavior.h"


/////////////////////////////////////////////////////////////////////////////////////////////////////////
// Init, this part is always similar, constructor, copy constructor, etc
/////////////////////////////////////////////////////////////////////////////////////////////////////////

// constructor
MyBehavior::MyBehavior(MObject3d * parentObject):
MBehavior(parentObject),
m_rotationSpeed(1)
{}

// copy constructor
MyBehavior::MyBehavior(MyBehavior & behavior, MObject3d * parentObject):
MBehavior(parentObject),
m_rotationSpeed(behavior.m_rotationSpeed)
{}

// destructor
MyBehavior::~MyBehavior(void)
{}

// destroy function : always similar
void MyBehavior::destroy(void)
{
	delete this;
}

// getNew function : always similar
MBehavior * MyBehavior::getNew(MObject3d * parentObject)
{
	return new MyBehavior(parentObject);
}

// getCopy function : always similar
MBehavior * MyBehavior::getCopy(MObject3d * parentObject)
{
	return new MyBehavior(*this, parentObject);
}

/////////////////////////////////////////////////////////////////////////////////////////////////////////
// Variables; allows to access custom variables from script and from Maratis Editor
/////////////////////////////////////////////////////////////////////////////////////////////////////////

unsigned int MyBehavior::getVariablesNumber(void){
	return 1;
}

MVariable MyBehavior::getVariable(unsigned int id)
{
	switch(id)
	{
	default:
		return MVariable("NULL", NULL, M_VARIABLE_NULL);
	case 0:
		return MVariable("rotationSpeed", &m_rotationSpeed, M_VARIABLE_FLOAT);
	}
}

/////////////////////////////////////////////////////////////////////////////////////////////////////////
// Events
/////////////////////////////////////////////////////////////////////////////////////////////////////////

// update function (called by MGame class by default)
void MyBehavior::update(void)
{
	MEngine * engine = MEngine::getInstance();
	MGame * game = engine->getGame();

	// check if the game is running, removing thif test will enable In-Editor update (like for the lookAt behavior)
	if(! game->isRunning())
		return;

	// get the associated parent object (who is using this behavior)
	MObject3d * parent = getParentObject();

	// lets rotate the parent object around the z axis, using our custom "rotationSpeed" variable
	parent->addAxisAngleRotation(MVector3(0, 0, 1), m_rotationSpeed);
}

GamePlugin.cpp

Now we have to edit our GamePlugin.cpp file to make it actually add our Behavior to the game, using MBehaviorManager.

//[...]
void StartPlugin(void)
{
	// get engine
	MEngine * engine = MEngine::getInstance();

	// add our behavior
	MBehaviorManager * behaviorManager = engine->getBehaviorManager();
	behaviorManager->addBehavior(MyBehavior::getStaticName(), M_OBJECT3D, MyBehavior::getNew);

	// set game
	game = new MyGame();
	engine->setGame(game);
}
//[...]