metersPerPixel function
Approximates meters per pixel at lat and zoom.
Implementation
@pragma('vm:prefer-inline')
double metersPerPixel(double lat, double zoom) {
const earthCircumference = 40075016.686;
final scale = math.cos(lat * math.pi / 180.0);
return earthCircumference * scale / (256 * math.pow(2.0, zoom));
}