v.out.vtk: Output double data type instead of float (OSGeo#2562)

Geometric information in the VTK Polydata dataset output of the v.out.vtk function are now saved as datatype double instead of float which is more suitable considering the amount of digits in geographic coordinates.

The 'POINTS n dataType' line now uses double dataType (float, double, int and more is allowed).

Fixes OSGeo#864.

Actual code change written by Brad ReDacted.

Co-authored-by: Brad ReDacted <brad.redacted@outlook.com>

vector/v.out.vtk/main.c

@@ -66,8 +66,7 @@ int main(int argc, char *argv[])
     dp_opt->key = "precision";
     dp_opt->type = TYPE_INTEGER;
     dp_opt->required = NO;
-    dp_opt->description =
-        _("Number of significant digits (floating point only)");
+    dp_opt->description = _("Number of significant digits");
 
     scale = G_define_option();
     scale->key = "zscale";
@@ -151,8 +150,8 @@ int main(int argc, char *argv[])
     if (dp_opt->answer) {
         if (sscanf(dp_opt->answer, "%d", &dp) != 1)
             G_fatal_error(_("Failed to interpret 'dp' parameter as an integer"));
-        if (dp > 8 || dp < 0)
-            G_fatal_error(_("dp has to be from 0 to 8"));
+        if (dp > 16 || dp < 0)
+            G_fatal_error(_("dp has to be from 0 to 16"));
     }
     else {
         dp = 8;                 /*This value is taken from the lib settings in G_feature_easting */

vector/v.out.vtk/writeVTK.c

@@ -200,7 +200,7 @@ int write_vtk_points(FILE * ascii, struct Map_info *Map, VTKInfo * info,
 
     /************************************************/
 
-    fprintf(ascii, "POINTS %i float\n", info->maxnumpoints);
+    fprintf(ascii, "POINTS %i double\n", info->maxnumpoints);
 
     /*For every available vector type */
     for (k = 0; k < typenum; k++) {