/* -*- c++ -*-
 * Copyright ©2008 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 "content_loxodrome.h"

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

		pi->name = "Loxodrome paths";
		pi->author = "Hugo Mills";
		pi->copyright = "©2008 Hugo Mills";
		pi->version = 0x00200;
		pi->parser = Content_Loxodrome::parse;
		return pi;
	}
	else
		return NULL;
}

Content* Content_Loxodrome::parse(
	ConfigLexer* lex,
	const std::string& type,
	const std::string& subtype
	)
{
	if(type != "loxodrome")
		return NULL;

	double x0 = 0.0;
	double y0 = 0.0;
	double x1 = 1.0;
	double y1 = 1.0;
	int loops = 0;
	bool solid = false;
	ivec3 col1(255);

	while(!lex->eos())
	{
		if(readkeyedvalue(lex, "start", &x0, &y0)
		   || readkeyedvalue(lex, "end", &x1, &y1)
		   || readkeyedvalue(lex, "loops", &loops)
		   || readbooleanvalue(lex, "solid", &solid)
		   || readkeyedvalue(lex, "colour", &col1[0], &col1[1], &col1[2])
			)
		{
		}
		else
			throw(UnknownConfigToken(lex));
	}

	return new Content_Loxodrome(x0, y0, x1, y1, loops-1, solid, col1);
}

Content_Loxodrome::Content_Loxodrome(
	double x0, double y0,
	double x1, double y1,
	int loops, bool s,
	const ivec3& col1
	)
	: solid(s), colour(col1)
{
	x0 = degrad(x0);
	x1 = degrad(x1);
	y0 = degrad(y0);
	y1 = degrad(y1);

	double sigma0 = asinh(tan(y0));
	double sigma1 = asinh(tan(y1));

	double l = 2*M_PI*loops;

	lon0 = x0;                     // Longitude origin for t=0
	lons = (x1 + l - x0);          // Longitude distance for t=0 to t=1
	k = (sigma1-sigma0)/lons;      // "Slope" value
	C = x0 - sigma0/k;             // "Offset" value
}

void Content_Loxodrome::plot(
	Output* bitmap,
	XfView* viewport,
	XfMap* projection,
	XfOrbit* orbit,
	XfSphere* sphere
	)
{
	dvec2 latlong;
	dvec3 globe_pos;
	dvec3 shifted_pos;
	dvec2 map_pos;
	ivec2 vp_pos;

	// Draw loxodrome
	double t = 0.0;
	while(t <= 1.0)
	{
		latlong[0] = lon0 + lons * t;
		latlong[1] = atan(sinh(k * (latlong[0]-C)));

		if(sphere->f(globe_pos, latlong)
		   && orbit->f(shifted_pos, globe_pos)
		   && projection->f(map_pos, shifted_pos)
		   && viewport->f(vp_pos, map_pos))
		{
			bitmap->setpixel(vp_pos, colour);
		}
		else
		{
			// Do nothing, and move on to the next point
		}
		t += 0.01;
	}
}