grdmask with region '-Rg' not recognising longitudes more than 180

[JonathonLeonard]

We are having a problem where grdmask is not recognising topologies that have a longitude between 180-360 when the region is set to '-Rg'. However it seems to work fine with region set it '-Rd'.

To demonstrate I have attached a folder with a script and a sample topology file:
grdmask_issue.zip

The topology file contained in the above file (test_topology.xy) defines three polygons- two that have longitudes <180 and one >180. For completeness, here is the contents of test_topology.xy:

> An example of a polygon that works fine with grdmask
0 0
0 -5
5 -5
5 0
0 0
> This works too
170 -20
170 -25
180 -25
180 -20
170 -20
> An example of a polygon between 181 and 360 that doesn't plot
189 -20
189 -25
194 -25
194 -20
189 -20

The below line of code will not recognise the polygon >180:

gmt grdmask -Rg test_topology.xy -I0.25 -N0/0/1 -r -Vd -GRg_flat_slab_mask.nc

While the below line will recognise all polygons:

gmt grdmask -Rd test_topology.xy -I0.25 -N0/0/1 -r -Vd -GRd_flat_slab_mask.nc

A work around would be to do the grdmask command with '-Rd' then use grdedit -S -Rg to have it back to the 0-360 longitude range, however I just thought I'd report this bug to see if anyone has any idea what's going on.

Actual outcome
Only polygons that exist within longitudes <180 will be masked by grdmask

Expected outcome
All polygons that exist from 0-360 longitude should be masked.

System information

• Operating system: MacOS Monterey (on an M1 Apple Silicon Chip)
• GMT version (gmt --version): 6.4.0

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