/**
 * <p>
 * Control function implementing "move in a direction"
 * </p>
 * @author     Michael Schuresko
 * @version    %I%, %G%
 * @since      1.0
 */
public class ControlFuncMoveDir implements IControlFunc
{

    double [] m_arrDir;
    

    
    
    public ControlFuncMoveDir() 
    {
	m_arrDir = null;
	
	
    }

    public ControlFuncMoveDir(ControlFuncMoveDir src)
    {
    setVel(src.m_arrDir);
    }
    
    public ControlFuncMoveDir(double lfX, double lfY) {
    	m_arrDir = new double[2];
    	m_arrDir[0] = lfX;
    	m_arrDir[1] = lfY;
    }

    public ControlFuncMoveDir(double [] arrPtTowards)
    {
    setVel(arrPtTowards);
	
    }
    
    public boolean directionConstantQ(double lfCurrTime, 
			  double arrLfStateSrc[], 
			  ISensor sensors,
			  IEnvironment env,
			  ILogicVarBundle logicVars,
			  int nIdxOffsetState) {
  	return true;
  }
 



    /**
     * sets a new point to move towards, possibly re-assigning
     * control function dimension (some care must be taken by programmer
     * here)
     */
    public void setVel(double [] arrVel)
    {
	if(m_arrDir == null || 
	   m_arrDir.length != arrVel.length) 
	    {
		m_arrDir = new double[arrVel.length];
	    }
	for(int i = 0; i < arrVel.length; ++i)
	    {
		m_arrDir[i] = arrVel[i];
	    }
    }

    public double [] getVel()
    {
    	return m_arrDir;
    }

    public double [] getVelCopy()
    {
    	if(m_arrDir == null) {
    		return null;
    	}
    	double [] arrLfRes = new double[m_arrDir.length];
    	for(int i = 0; i < m_arrDir.length; ++i) {
    		arrLfRes[i] = m_arrDir[i];
    	}
    	return arrLfRes;
    }
    

    /**
     * clones this object (similar to "clone" supported by IClonable 
     * interface).
     */
    public IControlFunc makeCopy()
    {
	return new ControlFuncMoveDir(this);
    }

    /**
     * <p>
     * Updates arrLfDerivDst with the instantaneous derivatives
     * of the continuous-time component of the agent's state 
     * given its current state and sensor readings
     * </p>
     * @param lfCurrTime current time (for time-varying systems)
     * @param arrLfStateSrc vector of global state of the system
     * @param sensors sensors 
     * @param env environment
     * @param logicVars discrete components of agent internal state
     * @param arrLfDerivDst Destination for storing derivative values.
     * @param nIdxOff Offset index into the global state vector 
     * corresponding to the beginning of the parameters for this agent.
     * @since 1.0
     */
    public void getDerivs(double lfCurrTime, 
			  double arrLfStateSrc[], 
			  ISensor sensors,
			  IEnvironment env,
			  ILogicVarBundle logicVars,
			  double arrLfDerivDst[],
			  int nIdxOff)
    {
	
	for(int i = 0; i < m_arrDir.length; ++i)
	    {
		arrLfDerivDst[nIdxOff+i] = 
		    m_arrDir[i];
	    }
	
	
    }
   
    /**
     * returns dimensionality of the state vector corresponding to one agent
     * @return dimensionality of the state vector corresponding to one agent
     */
    public int getNumStateVars()
    {
	if(m_arrDir == null) { return 0; }
	return m_arrDir.length;
    }

    
}