/* -*- C++ -*-
 * Copyright ©2004 Hugo Mills <hugo@carfax.org.uk>
 *
 * This software is distributed under the terms of the GNU GPL v3
 * For more information on the GPL, see the file COPYING or 
 * visit http://www.gnu.org/
 *
 * This software is distributed without warranty
 */

#include "xfmap_planarequalarea.h"

extern "C" PluginInfo* getmodules(int i)
{
	if(i==0)
	{
		PluginInfo_Map* pi = new PluginInfo_Map();

		pi->name = "Lambert's Azimuthal Equal Area";
		pi->author = "Hugo Mills";
		pi->copyright = "©2005 Hugo Mills";
		pi->version = 0x10000;
		pi->parser = XfMap_PlanarEqualArea::parser;
		return pi;
	}
	else
		return NULL;
}

XfMap* XfMap_PlanarEqualArea::parser(ConfigLexer* lex,
									 const std::string& type,
									 const std::string& subtype
	)
{
	if(type == "planar" && subtype == "equal-area"
	   || type == "lambert-equal-area" && subtype == ""
	   || type == "lambert" && subtype == "")
	{
		double limit = 180.0;

		while(!lex->eos())
		{
			if(!readkeyedvalue(lex, "limit", &limit))
				throw(UnknownConfigToken(lex));
		}

		return new XfMap_PlanarEqualArea(degrad(limit));
	}
	else
		return NULL;
}

bool XfMap_PlanarEqualArea::f(dvec2& result, const dvec3& pos) const
{
	if(acos(pos[2]) > limit)
		return false;
	double m = sqrt(2*(1-pos[2]) / (pos[0]*pos[0] + pos[1]*pos[1])) / 2;

	result[0] = m * pos[0];
	result[1] = m * pos[1];

	return true;
}

bool XfMap_PlanarEqualArea::g(dvec3& result, const dvec2& pos) const
{
	double r2 = pos[0]*pos[0] + pos[1]*pos[1];

	result[2] = 1-r2*2;
	if(result[2] < -1
	   || result[2] > 1
	   || acos(result[2]) > limit)
		return false;

	double m = sqrt(1-r2) * 2;
	result[0] = m * pos[0];
	result[1] = m * pos[1];

	return true;
}