Hermite.java

package curves;

import java.util.ArrayList;

/**
 * Hermite Spline calculator created using PMT(t). Hermetic curves pass directly through 
 * the points provided and may be handy in our situation.
 * 
 * @author asevans
 * 
 */
public class Hermite{

	private int order=4;
	private ArrayList<PointObject> controlObjects;
	
	public Hermite(){
		
	}
	
	

	public int getOrder() {
		return order;
	}



	public void setOrder(int order) {
		this.order = order;
	}



	public ArrayList<PointObject> getControlObjects() {
		return controlObjects;
	}

	public void setControlObjects(ArrayList<PointObject> controlObjects) {
		this.controlObjects = controlObjects;
	}
	
	/**
	 * Get a Point from a hermite curve from four PointObject objects
	 * by reducing the matrix equation from right to left.
	 * 
	 * @param p1
	 * @param p2
	 * @param p3
	 * @param p4
	 * @return
	 */
	private PointObject calcPoint(PointObject p1, PointObject p2, PointObject p3, PointObject p4){
		PointObject retobject=new PointObject();
	
		
		float basisax=(float)((2*p1.getX())-(2*p2.getX())+p3.getX()+p4.getX());
		float basisay=(float)((2*p1.getY())-(2*p2.getY())+p3.getY()+p4.getY());
		
		float basisbx=(float)((-3*p1.getX())+(3*p2.getX())-(2*p3.getX())-p4.getX());
		float basisby=(float)((-3*p1.getY())+(3*p2.getY())-(2*p3.getY())-p4.getY());
		
		float basiscx=(float)p3.getX();
		float basiscy=(float)p3.getY();
		
		float basisdx=(float)p1.getX();
		float basisdy=(float)p1.getY();
		
		float t;
		
		//get the vector determinant
		for(int i=0;i<(order-1);i++){
			t=i/order;
			retobject.setX(((basiscx+t*(basisbx+t*basisax))*t+basisdx));
			retobject.setY(((basiscy+t*(basisby+t*basisay))*t+basisdy));
		}
		
		return retobject;
	}
	
	/**
	 * Calculates a hermite curve
	 * @return
	 */
	private ArrayList<PointObject> calcCurvePoints(){
		//TODO calculate the hermite curve
		ArrayList<PointObject> po=new ArrayList<PointObject>();
		
		int start=0;
		
		if(controlObjects.size()>=3)
		{
			po.add(controlObjects.get(0));
			po.add(controlObjects.get(1));
			po.add(controlObjects.get(2));
			
			if(controlObjects.size()>3){
				for(int i=3;i<controlObjects.size();i++){
					po.add(calcPoint(controlObjects.get(start),controlObjects.get((start+1)),controlObjects.get(start+2),controlObjects.get(start+3)));
				}
			}
		}
		else
		{
			if(controlObjects==null)
			{
				try{
					throw new NullPointerException("No Control Points Provided");
				}catch(NullPointerException e){
					e.printStackTrace();
				}
			}
			else{
				for(int i=0;i<controlObjects.size();i++){
					po.add(controlObjects.get(i));
				}
			}
			
		}
		
		return po;
	}
	
	/**
	 * Run the program and get an ArrayList<PointObject> of spline points.
	 * The number of points returned depends on the number of control points provided.
	 * @return
	 */
	public ArrayList<PointObject> getCurvePoints(){
		return calcCurvePoints();
	}
	
}