import java.io.*;
import java.util.*;
import java.lang.Math.*;

public class spline3D
{
    private double minhop = 0.39;
    private double maxhop = 0.40;
	private double D = 0.001;
    
    
    private static double[][][] mA =
    {
        {{1,0,0,0},{0,0,0,0},{0,0,0,0},{0,0,0,0}},
        {{1,0,0,0},{-1,1,0,0},{0,0,0,0},{0,0,0,0}},
        {{1,0,0,0},{-3,4,-1,0},{2,-4,2,0},{0,0,0,0}},
        {{1,0,0,0},{-5.5,9,-4.5,1},{9,-22.5,18,-4.5},{-4.5,13.5,-13.5,4.5}}
    };

    public spline3D()
    {
    }
    
    public Vector generate( vector3D[] vA )
    {
        Vector V = new Vector();
	    
	    double T = 0;
	    double TT = 0;
	    vector3D newPoint = null;
	    vector3D oldPoint = null;
        vector3D tmpPoint = null;
        vector3D endPoint = null;
        
	    // add first point
	    oldPoint = new vector3D( vA[0] );
	    V.addElement( new vector3D( oldPoint ) );
	    
	    // while not finished
	    do
	    {
	        // first guess at point
	        TT = T + D;
	        //System.out.println( "trying " + TT );
	        newPoint = matrix( vA, TT );
	        tmpPoint = new vector3D( newPoint );
	        tmpPoint.sub( oldPoint );
	        
	        // while to long
	        while( tmpPoint.length() > maxhop )
	        {
	            TT -= D;
	            //System.out.println( "trying " + TT );
	            newPoint = matrix( vA, TT );
	            tmpPoint = new vector3D( newPoint );
	            tmpPoint.sub( oldPoint );
	        }

            // while too short
	        while( tmpPoint.length() < minhop )
	        {
	            TT += D;
	            //System.out.println( "trying " + TT );
	            newPoint = matrix( vA, TT );
	            tmpPoint = new vector3D( newPoint );
	            tmpPoint.sub( oldPoint );
	        }
	        
	        // just right
	        T = TT;
	        V.addElement( newPoint );
	        oldPoint.set( newPoint );
	        
	        // check distance
	        endPoint = new vector3D( vA[1] );
	        endPoint.sub( newPoint );
	    }
	    while( endPoint.length() > maxhop );
	    
	    return V;
    }

    private vector3D matrix( vector3D[] vP, double fT )
    {
	    int dS = vP.length;
	    double viT[] = new double[dS];
	    viT[0] = 1;
	    for( int viC = 1; viC < dS; viC++ )
		    viT[viC] = viT[viC-1] * fT;
		    
		vector3D result = new vector3D();
	    for( int vmR = 0; vmR < dS; vmR++ )
	    {
	        for( int vmC = 0; vmC < dS; vmC++ )
	        {
	            vector3D temp = new vector3D( vP[vmC] );
	            temp.mul( mA[dS-1][vmR][vmC] );
	            temp.mul( viT[vmR] );
	            result.add( temp );
			}
		}
	    return result;
    }
}