// latlon.cpp
//
// Copyright (C) 2003, 2004 Jason Bevins
//
// This library is free software; you can redistribute it and/or modify it
// under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation; either version 2.1 of the License, or (at
// your option) any later version.
//
// This library is distributed in the hope that it will be useful, but WITHOUT
// ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
// FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
// License (COPYING.txt) for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with this library; if not, write to the Free Software Foundation,
// Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
//
// The developer's email is jlbezigvins@gmzigail.com (for great email, take
// off every 'zig'.)
//
module noise.latlon;

private {
	import std.math;
	import noise.mathconsts;
}

/// Converts latitude/longitude coordinates on a unit sphere into 3D
/// Cartesian coordinates.
///
/// @param lat The latitude, in degrees.
/// @param lon The longitude, in degrees.
/// @param x On exit, this parameter contains the @a x coordinate.
/// @param y On exit, this parameter contains the @a y coordinate.
/// @param z On exit, this parameter contains the @a z coordinate.
///
/// @pre lat must range from @b -90 to @b +90.
/// @pre lon must range from @b -180 to @b +180.
void LatLonToXYZ (double lat, double lon, ref double x, ref double y, ref double z)
{
  double r = cos (DEG_TO_RAD * lat);
  x = r * cos (DEG_TO_RAD * lon);
  y =     sin (DEG_TO_RAD * lat);
  z = r * sin (DEG_TO_RAD * lon);
}