161 lines
4.1 KiB
C++
161 lines
4.1 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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// 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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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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point2d cart_to_polar_2d(point2d in) {
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point2d result;
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result.dist = sqrt( in.x * in.x + in.y * in.y );
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result.theta = atan2(in.y, in.x);
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return(result);
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}
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void batch_cart_to_polar_2d(point2d *in, point2d *out, int size) {
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int i;
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for ( i = 0; i < size; i++ ) {
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out[i] = cart_to_polar_2d( in[i] );
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}
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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, as well as a potential orientation
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// angle, generate the corresponding lon and lat of the original 2d
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// verticies.
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void make_area(point2d orig, point2d *cart, point2d *result,
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int size, double angle ) {
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point2d rad[size];
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int i;
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// convert to polar coordinates
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batch_cart_to_polar_2d(cart, rad, size);
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for ( i = 0; i < size; i++ ) {
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printf("(%.2f, %.2f)\n", rad[i].dist, rad[i].theta);
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}
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printf("\n");
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// rotate by specified angle
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for ( i = 0; i < size; i++ ) {
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rad[i].theta += angle;
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while ( rad[i].theta > FG_2PI ) {
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rad[i].theta -= FG_2PI;
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}
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printf("(%.2f, %.2f)\n", rad[i].dist, rad[i].theta);
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}
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printf("\n");
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for ( i = 0; i < size; i++ ) {
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result[i] = calc_lon_lat(orig, rad[i]);
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printf("(%.8f, %.8f)\n", result[i].lon, result[i].lat);
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}
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printf("\n");
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}
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// generate an area for a runway
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void gen_runway_area( double lon, double lat, double heading,
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double length, double width,
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point2d *result, int *count)
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{
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point2d cart[4];
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point2d orig;
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double l, w;
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int i;
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orig.lon = lon;
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orig.lat = lat;
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l = (length / 2.0) + (length * 0.1);
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w = (width / 2.0) + (width * 0.1);
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// generate untransformed runway area vertices
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cart[0].x = l; cart[0].y = w;
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cart[1].x = l; cart[1].y = -w;
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cart[2].x = -l; cart[2].y = -w;
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cart[3].x = -l; cart[3].y = w;
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for ( i = 0; i < 4; i++ ) {
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printf("(%.2f, %.2f)\n", cart[i].x, cart[i].y);
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}
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printf("\n");
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make_area(orig, cart, result, 4, heading);
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for ( i = 0; i < 4; i++ ) {
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printf("(%.8f, %.8f)\n", result[i].lon, result[i].lat);
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}
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printf("\n");
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*count = 4;
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}
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// $Log$
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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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