#include "stdafx.h"
#include "BaiDuMap.h"
#include <math.h>
#include "stdlib.h" 

double BaiDuMap::DEF_PI = 3.14159265359; // PI
double BaiDuMap::DEF_2PI = 6.28318530712; // 2*PI
double BaiDuMap::DEF_PI180 = 0.01745329252; // PI/180.0
double BaiDuMap::DEF_R = 6370693.5; // radius of earth

BaiDuMap::BaiDuMap()
{
}


BaiDuMap::~BaiDuMap()
{
}

double BaiDuMap::GetShortDistance(double lon1, double lat1, double lon2, double lat2)
{
	double ew1, ns1, ew2, ns2;
	double dx, dy, dew;
	double distance;
	// 角度转换为弧度
	ew1 = lon1 * DEF_PI180;
	ns1 = lat1 * DEF_PI180;
	ew2 = lon2 * DEF_PI180;
	ns2 = lat2 * DEF_PI180;
	// 经度差
	dew = ew1 - ew2;
	// 若跨东经和西经180 度，进行调整
	if (dew > DEF_PI)
		dew = DEF_2PI - dew;
	else if (dew < -DEF_PI)
		dew = DEF_2PI + dew;
	dx = DEF_R * cos(ns1) * dew; // 东西方向长度(在纬度圈上的投影长度)
	dy = DEF_R * (ns1 - ns2); // 南北方向长度(在经度圈上的投影长度)
	// 勾股定理求斜边长
	distance = sqrt(dx * dx + dy * dy);
	return distance;
}

double BaiDuMap::GetLongDistance(double lon1, double lat1, double lon2, double lat2)
{
	double ew1, ns1, ew2, ns2;
	double distance;

	// 角度转换为弧度
	ew1 = lon1 * DEF_PI180;
	ns1 = lat1 * DEF_PI180;
	ew2 = lon2 * DEF_PI180;
	ns2 = lat2 * DEF_PI180;
	// 求大圆劣弧与球心所夹的角(弧度)
	distance = sin(ns1) * sin(ns2) + cos(ns1) * cos(ns2) * cos(ew1 - ew2);
	// 调整到[-1..1]范围内，避免溢出
	if (distance > 1.0)
		distance = 1.0;
	else if (distance < -1.0)
		distance = -1.0;
	// 求大圆劣弧长度
	distance = DEF_R * acos(distance);
	return distance;
}

double BaiDuMap::test()
{
	//double mLat1 = 22.554201; // point1纬度
	//double mLon1 = 113.934357; // point1经度
	//double mLat2 = 22.553480;// point2纬度
	//double mLon2 = 113.932922;// point2经度

	double mLat1 = 22.575468; // point1纬度
	double mLon1 = 113.878807; // point1经度
	double mLat2 = 22.553425;// point2纬度
	double mLon2 = 113.932861;// point2经度


	double distance = GetShortDistance(mLon1, mLat1, mLon2, mLat2);

	return distance;
}