void Ring::length(double x1, double x2, double y1, double y2){
double L = arclen(x1,x2,y1,y2);
int x = getBin(x2);
int y = getBin(y1);
probMap[make_pair(x,y)]+= L;
probMap[make_pair(y,x)]+= L;
}
/**
* @brief geodist 计算2个经纬度表示的地球上的两个地点之间的距离
* @param lat1
* @param lon1
* @param lat2
* @param lon2
* @param d 返回的距离, 海里单位
* @return
*/
int geodist(double lat1,
double lon1,
double lat2,
double lon2,
double *d) {
if (lat1 < -90.0 || lat1 > 90.0 || lat2 < -90.0 || lat2 > 90.0 ) {
return -1;
}
if (lon1 < -180.0 || lon1 > 180.0 || lon2 < -180.0 || lon2 > 180.0 ) {
return -1;
}
SPoint p1, p2;
//将经纬度转成球座标点
getSPointFromLatLon (lat1, lon1, &p1);
getSPointFromLatLon (lat2, lon2, &p2);
arclen (&p1, &p2, d);
return 0;
}
int geodist(double lat1, double lon1, double lat2, double lon2, double *d)
{
SPoint p1, p2;
/*****************************************************************************
* Validate the coordinates. *
*****************************************************************************/
if (lat1 < -90.0 || lat1 > 90.0 || lat2 < -90.0 || lat2 > 90.0)
return -1;
if (lon1 < -180.0 || lon1 > 180.0 || lon2 < -180.0 || lon2 > 180.0)
return -1;
/*****************************************************************************
* Convert each latitude and longitude to spherical coordinates in radians *
* using the earth's radius for rho. *
*****************************************************************************/
p1.rho = EARTH_RADIUS;
p1.theta = -1.0 * DEGTORAD(lon1);
p1.phi = (DEGTORAD(-1.0 * lat1)) + DEGTORAD(90.0);
p2.rho = EARTH_RADIUS;
p2.theta = -1.0 * DEGTORAD(lon2);
p2.phi = (DEGTORAD(-1.0 * lat2)) + DEGTORAD(90.0);
/*****************************************************************************
* Compute the distance between the points. *
*****************************************************************************/
arclen(p1, p2, d);
return 0;
}
// sin(lat) ]
//
// |v0 x v1| ~ sqrt( cos(lat0)^2 cos(lat1)^2 dlon^2 + dlat^2 )
float cos_lat1_sq = cosf(lat1_rad);
cos_lat1_sq *= cos_lat1_sq;
float dlat = lat1_rad - lat0_rad;
float dlon = lon1_rad - lon0_rad;
return Rearth * sqrtf( dlon*dlon * cos_lat0_sq * cos_lat1_sq +
dlat*dlat );
}
float len = arclen( pois[ipoi].lat_rad, pois[ipoi].lon_rad );
return MIN_MARKER_DIST < len && len < MAX_MARKER_DIST;
}
static void addToActive( int ipoi )
{
active_pois[N_active_pois++] = ipoi;
}
void initPOIs( float lat_rad, float lon_rad )
{
// alloc an upper-bound amount of memory. It's probably too much, but I know
// we'll never run out
int Npois = sizeof(pois) / sizeof(pois[0]);
if( active_pois == NULL )
