func SplitPolygonAtGrid(g *geos.Geos, geom *geos.Geom, gridWidth, currentGridWidth float64) ([]*geos.Geom, error) { var result []*geos.Geom geomBounds := geom.Bounds() if geomBounds == geos.NilBounds { return nil, errors.New("couldn't create bounds for geom") } for _, bounds := range tileBounds(geom.Bounds(), currentGridWidth) { clipGeom := g.BoundsPolygon(bounds) if clipGeom == nil { return nil, errors.New("couldn't create bounds polygon") } part := g.Intersection(geom, clipGeom) if part == nil { return nil, errors.New("couldn't create intersection") } if !g.IsEmpty(part) && strings.HasSuffix(g.Type(part), "Polygon") { if gridWidth >= currentGridWidth { result = append(result, part) } else { moreParts, err := SplitPolygonAtGrid(g, part, gridWidth, currentGridWidth/10.0) if err != nil { return nil, err } result = append(result, moreParts...) } } } return result, nil }