233 lines
6.2 KiB
C++
233 lines
6.2 KiB
C++
// area.c -- routines to assist with inserting "areas" into FG terrain
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//
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// Written by Curtis Olson, started March 1998.
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//
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// Copyright (C) 1998 Curtis L. Olson - curt@me.umn.edu
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//
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// This program is free software; you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation; either version 2 of the License, or
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// (at your option) any later version.
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//
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// This program is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with this program; if not, write to the Free Software
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// Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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//
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// $Id$
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// (Log is kept at end of this file)
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//
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#include <math.h>
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#include <stdio.h>
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#include <Include/fg_constants.h>
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#include "area.hxx"
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#include "point2d.hxx"
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// calc new x, y for a rotation
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double rot_x(double x, double y, double theta) {
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return ( x * cos(theta) + y * sin(theta) );
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}
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// calc new x, y for a rotation
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double rot_y(double x, double y, double theta) {
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return ( -x * sin(theta) + y * cos(theta) );
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}
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// calc new lon/lat given starting lon/lat, and offset radial, and
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// distance. NOTE: distance is specified in meters (and converted
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// internally to radians)
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point2d calc_lon_lat( point2d orig, point2d offset ) {
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point2d result;
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// printf("calc_lon_lat() offset.theta = %.2f offset.dist = %.2f\n",
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// offset.theta, offset.dist);
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offset.dist *= METER_TO_NM * NM_TO_RAD;
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result.lat = asin( sin(orig.lat) * cos(offset.dist) +
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cos(orig.lat) * sin(offset.dist) * cos(offset.theta) );
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if ( cos(result.lat) < FG_EPSILON ) {
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result.lon = orig.lon; // endpoint a pole
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} else {
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result.lon =
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fmod(orig.lon - asin( sin(offset.theta) * sin(offset.dist) /
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cos(result.lat) ) + FG_PI, FG_2PI) - FG_PI;
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}
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return(result);
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}
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list < point2d >
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batch_cart_to_polar_2d( list < point2d > in_list)
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{
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list < point2d > out_list;
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list < point2d > :: iterator current;
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list < point2d > :: iterator last;
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point2d p;
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current = in_list.begin();
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last = in_list.end();
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while ( current != last ) {
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p = cart_to_polar_2d( *current );
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out_list.push_back(p);
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++current;
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}
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return out_list;
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}
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// given a set of 2d coordinates relative to a center point, and the
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// lon, lat of that center point (specified in degrees), as well as a
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// potential orientation angle, generate the corresponding lon and lat
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// of the original 2d verticies.
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list < point2d >
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gen_area(point2d origin, double angle, list < point2d > cart_list)
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{
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list < point2d > rad_list;
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list < point2d > result_list;
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list < point2d > :: iterator current;
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list < point2d > :: iterator last;
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point2d origin_rad, p;
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origin_rad.lon = origin.lon * DEG_TO_RAD;
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origin_rad.lat = origin.lat * DEG_TO_RAD;
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// convert to polar coordinates
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rad_list = batch_cart_to_polar_2d(cart_list);
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/*
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// display points
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printf("converted to polar\n");
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current = rad_list.begin();
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last = rad_list.end();
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while ( current != last ) {
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printf("(%.2f, %.2f)\n", current->theta, current->dist);
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++current;
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}
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printf("\n");
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*/
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// rotate by specified angle
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// printf("Rotating points by %.2f\n", angle);
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current = rad_list.begin();
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last = rad_list.end();
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while ( current != last ) {
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current->theta -= angle;
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while ( current->theta > FG_2PI ) {
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current->theta -= FG_2PI;
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}
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// printf("(%.2f, %.2f)\n", current->theta, current->dist);
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++current;
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}
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// printf("\n");
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// find actual lon,lat of coordinates
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// printf("convert to lon, lat relative to %.2f %.2f\n",
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// origin.lon, origin.lat);
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current = rad_list.begin();
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last = rad_list.end();
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while ( current != last ) {
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p = calc_lon_lat(origin_rad, *current);
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// convert from radians to degress
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p.lon *= RAD_TO_DEG;
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p.lat *= RAD_TO_DEG;
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// printf("(%.8f, %.8f)\n", p.lon, p.lat);
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result_list.push_back(p);
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++current;
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}
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// printf("\n");
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return result_list;
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}
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// generate an area for a runway
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list < point2d >
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gen_runway_area( double lon, double lat, double heading,
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double length, double width)
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{
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list < point2d > result_list;
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list < point2d > tmp_list;
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list < point2d > :: iterator current;
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list < point2d > :: iterator last;
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point2d p;
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point2d origin;
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double l, w;
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int i;
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/*
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printf("runway: lon = %.2f lat = %.2f hdg = %.2f len = %.2f width = %.2f\n",
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lon, lat, heading, length, width);
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*/
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origin.lon = lon;
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origin.lat = lat;
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l = length / 2.0;
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w = width / 2.0;
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// generate untransformed runway area vertices
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p.x = l; p.y = w; tmp_list.push_back(p);
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p.x = l; p.y = -w; tmp_list.push_back(p);
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p.x = -l; p.y = -w; tmp_list.push_back(p);
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p.x = -l; p.y = w; tmp_list.push_back(p);
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/*
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// display points
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printf("Untransformed, unrotated runway\n");
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current = tmp_list.begin();
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last = tmp_list.end();
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while ( current != last ) {
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printf("(%.2f, %.2f)\n", current->x, current->y);
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++current;
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}
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printf("\n");
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*/
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// rotate, transform, and convert points to lon, lat in degrees
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result_list = gen_area(origin, heading, tmp_list);
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/*
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// display points
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printf("Results in radians.\n");
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current = result_list.begin();
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last = result_list.end();
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while ( current != last ) {
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printf("(%.8f, %.8f)\n", current->lon, current->lat);
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++current;
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}
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printf("\n");
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*/
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return result_list;
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}
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// $Log$
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// Revision 1.3 1998/09/09 16:26:31 curt
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// Continued progress in implementing the convex hull algorithm.
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//
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// Revision 1.2 1998/09/04 23:04:48 curt
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// Beginning of convex hull genereration routine.
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//
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// Revision 1.1 1998/09/01 19:34:33 curt
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// Initial revision.
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//
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// Revision 1.1 1998/07/20 12:54:05 curt
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// Initial revision.
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//
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//
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