package graph.distort;
import graph.*;
import graph.filter.*;

/**
 * A filter that distorts the graph, based on work by
 * Sarkar and Brown at DEC research.
 * The transformations are:
 *
 * <PRE>
 *      T(x) = (d + 1)x / (dx + 1)      //translation
 *      M(x) = (d + 1) / (dx + 1)^2     //magnification
 * </PRE>
 *
 * @see graph.filter.Filter
 * @see graph.distort.PolarDistortion
 *
 * @author Michael Shilman <michaels@eecs.berkeley.edu>
 * @version $Id$
 */
 
class CartesianDistortion implements Filter {
	public int focus[] = new int[2];
	public int k;
	public static int s_distortIndex = AttributeManager.NO_INDEX;;
	public EmbedCanvas c;
	
	public CartesianDistortion() {
    	if(s_distortIndex == AttributeManager.NO_INDEX) {
    		s_distortIndex = AttributeManager.getIndex("Distortion");
    	}
	}
	
    public void apply(DistortionCanvas c) {

        float focusX = ((float)(focus[0] - c.BORDER)/(c.IMG_X/2.0f));
        float focusY = ((float)(focus[1] - c.BORDER)/(c.IMG_Y/2.0f));

//        float focusX = ((float)(c.focus[0] - c.BORDER + c.IMG_X/2.0f)/(float)c.IMG_X);
//        float focusY = ((float)(c.focus[1] - c.BORDER + c.IMG_Y/2.0f)/(float)c.IMG_Y);

		DistortionAttr a = (DistortionAttr)n.attrs[s_distortIndex];
        float x = n.x;
        float y = n.y;
        float nx = Math.abs(focusX - x);
        float ny = Math.abs(focusY - y);
        float mx = (c.k + 1.0f)/((c.k*nx + 1.0f)*(c.k*nx + 1.0f));
        float my = (c.k + 1.0f)/((c.k*ny + 1.0f)*(c.k*ny + 1.0f));
        float tx = (c.k + 1.0f)*nx/(c.k*nx + 1);
        float ty = (c.k + 1.0f)*ny/(c.k*ny + 1);
        if(x < focusX)
            tx = -tx;
        if(y < focusY)
            ty = -ty;

        c.points[i][j][0] = (tx*(c.IMG_X/2) + c.focus[0]);
        c.points[i][j][1] = (ty*(c.IMG_Y/2) + c.focus[1]);
        c.dims[i][j][0] = (mx*c.BOX_X);
        c.dims[i][j][1] = (my*c.BOX_Y);
    }
    
	public Frame buildGUI() { return new Frame(getName()); }
	public Component buildThumbnail() { return null; }
	public String getName() { return "Cartesian Distortion"; }
}