MBTFPQProjection.java

/*
Copyright 2006 Jerry Huxtable

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

   http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

/*
 * This file was semi-automatically converted from the public-domain USGS PROJ source.
 */
package com.jhlabs.map.proj;

import java.awt.geom.*;
import com.jhlabs.map.*;

public class MBTFPQProjection extends Projection {

	private final static int NITER = 20;
	private final static double EPS = 1e-7;
	private final static double ONETOL = 1.000001;
	private final static double C = 1.70710678118654752440;
	private final static double RC = 0.58578643762690495119;
	private final static double FYC = 1.87475828462269495505;
	private final static double RYC = 0.53340209679417701685;
	private final static double FXC = 0.31245971410378249250;
	private final static double RXC = 3.20041258076506210122;

	public Point2D.Double project(double lplam, double lpphi, Point2D.Double out) {
		double th1, c;
		int i;

		c = C * Math.sin(lpphi);
		for (i = NITER; i > 0; --i) {
			out.y -= th1 = (Math.sin(.5*lpphi) + Math.sin(lpphi) - c) /
				(.5*Math.cos(.5*lpphi)  + Math.cos(lpphi));
			if (Math.abs(th1) < EPS) break;
		}
		out.x = FXC * lplam * (1.0 + 2. * Math.cos(lpphi)/Math.cos(0.5 * lpphi));
		out.y = FYC * Math.sin(0.5 * lpphi);
		return out;
	}

	public Point2D.Double projectInverse(double xyx, double xyy, Point2D.Double out) {
		double t = 0;

		double lpphi = RYC * xyy;
		if (Math.abs(lpphi) > 1.) {
			if (Math.abs(lpphi) > ONETOL)	throw new ProjectionException("I");
			else if (lpphi < 0.) { t = -1.; lpphi = -Math.PI; }
			else { t = 1.; lpphi = Math.PI; }
		} else
			lpphi = 2. * Math.asin(t = lpphi);
		out.x = RXC * xyx / (1. + 2. * Math.cos(lpphi)/Math.cos(0.5 * lpphi));
		lpphi = RC * (t + Math.sin(lpphi));
		if (Math.abs(lpphi) > 1.)
			if (Math.abs(lpphi) > ONETOL)
				throw new ProjectionException("I");
			else
				lpphi = lpphi < 0. ? -MapMath.HALFPI : MapMath.HALFPI;
		else
			lpphi = Math.asin(lpphi);
		out.y = lpphi;
		return out;
	}

	public boolean hasInverse() {
		return true;
	}

	public String toString() {
		return "McBryde-Thomas Flat-Polar Quartic";
	}

}