import java.awt.*;
import java.awt.image.*;

class HFEngine extends Thread {

    static final float C = (float)Math.tan(85*Math.PI/180);
    //constant for viewing angle between the eyes
    static final float C4 = C*C*C*C;
    static final float C2 = C*C;
    private int[] dest, pattern;
    private int patternwidth, destwidth, h;
    MemoryImageSource yar;

    HFEngine (int[] dest, int[] pattern,
              int destwidth, int patternwidth, int h) {
	this.dest = dest;
	this.pattern = pattern;
	this.patternwidth = patternwidth;
	this.destwidth = destwidth;
        this.h = h;
    }

    public void run() {
        System.out.println("Running");
        float[] lastSegment = new float[patternwidth*2];
	float[] newSegment = new float[patternwidth*2];
	float[] pointer;
	int lastwidth = 0;
	int newwidth = 0;
	int index = 0; int x = 0; int y = 0; int lastx = 0;
	float radius = (destwidth-patternwidth)/2;
	float rx = 0; float xe = 0; float scalefactor = 0; float xval = 0;
	float lastxe = 0;
	while (index < dest.length) {
	    if (Math.abs(y-radius) != radius)
		scalefactor =
		    (float)(Math.sqrt(radius*radius-(y-radius)*(y-radius)));
	    else scalefactor = 1;
	    for (x = 0; x< patternwidth; x++) {
		dest[index] = pattern[y*patternwidth+x];
		lastSegment[x] = x;
		index++;
	    }
	    lastwidth = patternwidth-1;
	    lastx = x;
	    newwidth = -1;
	    for ( ; x< destwidth; x++) {
		rx = (x-patternwidth-radius)/scalefactor;
		if ( (4*C4*rx*rx-4*(1+C2)*(C2*rx*rx-1)) >= 0)
		    xe = (float)(2*C2*rx+Math.sqrt(4*C4*rx*rx-4*(1+C2)*(C2*rx*rx-1)))/(2*(1+C2));
		else xe = rx;
		if (x == patternwidth) lastxe = xe;
		if ((xe-lastxe)*scalefactor > lastwidth) {
		    pointer = lastSegment;
		    lastSegment = newSegment;
		    newSegment = pointer;
		    lastwidth = newwidth;
		    newwidth = -1;
		    lastx = x;
		    lastxe = xe;
		    x--;
		} else {
                    xval = interpolate(lastSegment,(xe-lastxe)*scalefactor);
		    newSegment[x-lastx] = xval;
		    dest[index] = pattern[y*patternwidth+Math.round(xval)];
		    newwidth++;
		    index++;
		}
	    }
	    y++;
	}
        yar = new MemoryImageSource(destwidth, h, dest, 0, destwidth);
    }

    float interpolate(float[] array, float index) {
	int ceil = (int)Math.ceil(index);
	int floor = (int)Math.floor(index);
	if (ceil==floor) return array[ceil];
	else return (index-floor)*array[ceil]+(ceil-index)*array[floor];
    }

}