墨卡托坐标转经纬度

package main

import (
	"fmt"
	"log"
	"math"
)

var mcband = [6]float64{12890594.86, 8362377.87, 5591021, 3481989.83, 1678043.12, 0.0}
var mc2ll = [6][10]float64{
	{1.410526172116255e-8, 0.00000898305509648872, -1.9939833816331,
		200.9824383106796, -187.2403703815547, 91.6087516669843, -23.38765649603339,
		2.57121317296198, -0.03801003308653, 17337981.2},
	{-7.435856389565537e-9, 0.000008983055097726239, -0.78625201886289,
		96.32687599759846, -1.85204757529826, -59.36935905485877, 47.40033549296737,
		-16.50741931063887, 2.28786674699375, 10260144.86},
	{-3.030883460898826e-8, 0.00000898305509983578, 0.30071316287616,
		59.74293618442277, 7.357984074871, -25.38371002664745, 13.45380521110908,
		-3.29883767235584, 0.32710905363475, 6856817.37},
	{-1.981981304930552e-8, 0.000008983055099779535, 0.03278182852591, 40.31678527705744,
		0.65659298677277, -4.44255534477492, 0.85341911805263, 0.12923347998204,
		-0.04625736007561, 4482777.06},
	{3.09191371068437e-9, 0.000008983055096812155, 0.00006995724062, 23.10934304144901,
		-0.00023663490511, -0.6321817810242, -0.00663494467273, 0.03430082397953,
		-0.00466043876332, 2555164.4},
	{2.890871144776878e-9, 0.000008983055095805407, -3.068298e-8, 7.47137025468032,
		-0.00000353937994, -0.02145144861037, -0.00001234426596, 0.00010322952773,
		-0.00000323890364, 826088.5}}

const pi = 3.14159265358979324 * 3000.0 / 180.0

// ConvertMCT_2_BD09 将墨卡托坐标转换被BD09坐标（百度地图专用）
// log 经度 lat纬度
func ConvertMCT_2_BD09(lon, lat float64) (float64, float64) {
	if (lat < 0.0) || (lon < 0.0) {
		//国内经纬度都是正数
		log.Fatal("lat and lon must greater than 0!")
	}
	var ax [10]float64
	for i, v := range mcband {
		if lat >= v {
			ax = mc2ll[i]
			break
		}
	}
	e := ax[0] + ax[1]*lon
	i := lat / ax[9]
	aw := ax[2] + ax[3]*i + ax[4]*math.Pow(i, 2) + ax[5]*math.Pow(i, 3) +
		ax[6]*math.Pow(i, 4) + ax[7]*math.Pow(i, 5) + ax[8]*math.Pow(i, 6)
	fmt.Println(e, aw)
	return e, aw
}

//ConvertBD09_2GCJ03 用于把BD09坐标转成GCJ03
func ConvertBD09_2_GCJ03(lon, lat float64) (float64, float64) {
	x := lon - 0.0065
	y := lat - 0.006
	z := math.Sqrt(x*x+y*y) - 0.00002*math.Sin(y*pi)
	theta := math.Atan2(y, x) - 0.000003*math.Cos(x*pi)
	ggLon := z * math.Cos(theta)
	ggLat := z * math.Sin(theta)
	return ggLon, ggLat
}

func main() {
	fmt.Println(ConvertBD09_2_GCJ03(ConvertMCT_2_BD09(12945050.96, 4826978.52)))
}