/* -*- 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_pointprojected.h"

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

		pi->name = "Point Projected Planar (Stereographic and Gnomonic)";
		pi->author = "Hugo Mills";
		pi->copyright = "©2005 Hugo Mills";
		pi->version = 0x10000;
		pi->parser = XfMap_PointProjected::parser;
		return pi;
	}
	else
		return NULL;
}

XfMap* XfMap_PointProjected::parser(
	ConfigLexer* lex,
	const std::string& type,
	const std::string& subtype
	)
{
	if(type == "planar" && subtype == "stereographic")
		return new XfMap_PointProjected(1.0);
	if(type == "planar" && subtype == "gnomonic")
		return new XfMap_PointProjected(0.0);

	if(type == "planar" && subtype == "point-projected")
	{
		double pos = 0.0;

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

		return new XfMap_PointProjected(pos);
	}
	else
		return NULL;
}

bool XfMap_PointProjected::f(dvec2& result, const dvec3& pos) const
{
	double m = (proj+1) / (proj+pos[2]);
	result[0] = pos[0] * m;
	result[1] = pos[1] * m;

	return true;
}

bool XfMap_PointProjected::g(dvec3& result, const dvec2& pos) const
{
	// Ouch
	// Radius on the projection surface
	double r2 = pos[0]*pos[0] + pos[1]*pos[1];
	double r = sqrt(r2);
	// Radius from the z-axis on the sphere
	double s = pp1 + sqrt(r2*q + p12);
	s /= p12 + r2;
	// s *= r; -- This is in the equations to give the correct value of s,
	//            however note that you would have to multiply by r to get 
	//            the appropriate multiplier for result[0] and [1], so...

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

	return true;
}