Web Mercator Tile Conversion

Calculate Web Mercator Tile from WGS84 Longitude Latitude [Go]

package main

import (
	"fmt"
	"math"

	"github.com/wroge/wgs84"
)

type PixelMercator struct {
	A    float64
	Tile float64
	Zoom int
}

func (crs PixelMercator) res0() float64 {
	return 2 * math.Pi * crs.A / crs.Tile
}

func (crs PixelMercator) shift() float64 {
	return math.Pi * crs.A
}

func (crs PixelMercator) ToWGS84(a, b, c float64) (x0, y0, z0 float64) {
	res := crs.res0() / math.Pow(2, float64(crs.Zoom))
	north := b*res - crs.shift()
	east := a*res - crs.shift()
	return wgs84.WebMercator().ToWGS84(east, north, c)
}

func (crs PixelMercator) FromWGS84(x0, y0, z0 float64) (a, b, c float64) {
	east, north, h := wgs84.WebMercator().FromWGS84(x0, y0, z0)
	res := crs.res0() / math.Pow(2, float64(crs.Zoom))
	px := (east + crs.shift()) / res
	py := (north + crs.shift()) / res
	return px, py, h
}

func (crs PixelMercator) Contains(lon, lat float64) bool {
	return true
}

func main() {

	lon := 9.0
	lat := 52.0

	crs := PixelMercator{
		A:    6378137.0,
		Tile: 256.0,
		Zoom: 7,
	}

	px, py, _ := wgs84.To(crs)(lon, lat, 0)
	fmt.Println(px, py)
	// 17203.2 21944.235012200952

	lon, lat, _ = wgs84.From(crs).Round(3)(px, py, 0)
	fmt.Println(lon, lat)
	// 9 52
}

https://go.dev/play/p/zzg8uVSsJVI