/* -*- 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_cylorthographic.h"

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

		pi->name = "Cylindrical Orthographic";
		pi->author = "Hugo Mills";
		pi->copyright = "©2005 Hugo Mills";
		pi->version = 0x10000;
		pi->parser = XfMap_CylindricalOrthographic::parser;
		return pi;
	}
	else
		return NULL;
}

XfMap* XfMap_CylindricalOrthographic::parser(
	ConfigLexer* lex,
	const std::string& type,
	const std::string& subtype
	)
{
	if(type == "cylindrical" && subtype == "orthographic")
	{
		double parallel = 0.0;

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

		return new XfMap_CylindricalOrthographic(degrad(parallel));
	}
	else
		return NULL;
}

bool XfMap_CylindricalOrthographic::f(dvec2& result, const dvec3& pos) const
{
	result[0] = atan2(pos[0], pos[2]) / M_PI;
	result[1] = pos[1] / scale / M_PI;

	return true;
}

bool XfMap_CylindricalOrthographic::g(dvec3& result, const dvec2& pos) const
{
	result[1] = pos[1] * scale * M_PI;

	if(result[1] < -1 || result[1] > 1)
		return false;
	if(pos[0] < -1 || pos[0] > 1)
		return false;

	double m = sqrt(1-result[1]*result[1]);
	double a = pos[0] * M_PI;

	result[0] = m * sin(a);
	result[2] = m * cos(a);

	return true;
}

TraceState* XfMap_CylindricalOrthographic::initpath(
	TPCInsertIterator it,
	const dvec3& point) const
{
	CylindricalOrthographic_TraceState* rv 
		= new CylindricalOrthographic_TraceState();

	f(rv->previous, point);
	*it = TracePoint(rv->previous);

	return rv;
}

// We define 0.0 <= lambda < 4.0, running anti-clockwise from
// bottom-right. Integer values of lambda lie on the corners of the
// rectangle.

void XfMap_CylindricalOrthographic::pathpoint(TraceState* _state,
											  TPCInsertIterator it,
											  const dvec3& point) const
{
	CylindricalOrthographic_TraceState* state
		= dynamic_cast<CylindricalOrthographic_TraceState*>(_state);

	double maxy = 1.0 / (scale * M_PI);

	dvec2 current;
	f(current, point);

	if(fabs(state->previous[0] - current[0]) > 1.75)
	{
		if(state->previous[0] < current[0])
		{
			state->previous[0] += 2.0;
			double frac = (state->previous[0] - 1.0) / (state->previous[0] - current[0]);
			double y = (state->previous[1] - current[1]) * frac;
			double lambda = (y + maxy) / (2 * maxy);

			*it = TracePoint(-1.0, y, 3.0-lambda, false);
			*it = TracePoint(1.0, y, lambda, true);

			state->previous = current;
		}
		else
		{
			state->previous[0] -= 2.0;
			// FIXME: Similar code to the preceding
			state->previous = current;
		}
	}

	*it = current;
}

void XfMap_CylindricalOrthographic::tracepath(
	TPCInsertIterator it,
	double lambdafrom, double lambdato) const
{
	double maxy = 1.0 / (scale * M_PI);

	while(int(lambdafrom) != int(lambdato))
	{
		switch(int(lambdafrom))
		{
		case 0:
			// Draw to top right
			*it = TracePoint(1.0, maxy);
			lambdafrom = 1.0;
			break;
		case 1:
			// Draw to top left
			*it = TracePoint(-1.0, maxy);
			lambdafrom = 2.0;
			break;
		case 2:
			// Draw to bottom left
			*it = TracePoint(-1.0, -maxy);
			lambdafrom = 3.0;
			break;
		case 3:
			// Draw to bottom right
			*it = TracePoint(1.0, -maxy);
			lambdafrom = 0.0;
			break;
		}
	}
}