1. mapnik::projection const *_merc = new mapnik::projection("+init=epsg:3857");
  2. mapnik::projection const *_wgs84 = new mapnik::projection("+init=epsg:4326");
  3. mapnik::proj_transform const *transformer_ = new mapnik::proj_transform(*_merc, *_wgs84);
  4.  
  5. std::clog << "before reprojection:\n";
  6. mapnik::coord2d c = bb.center();
  7. std::clog << std::setw(10) << c.y << "," << c.x << "\n";
  8.  
  9. {
  10. std::clog << "after reprojection:\n";
  11. transformer_->backward(bb);
  12. transformer_->forward(bb);
  13. mapnik::coord2d c = bb.center();
  14. std::clog << std::setw(10) << c.y << "," << c.x << "\n";
  15. }
  16.  
  17. /*
  18. produces output:
  19.  
  20. before reprojection:
  21. 85.0483,-179.967
  22. after reprojection:
  23. 85.0442,-179.967
  24. */