Add methods to the grid to add sources and receivers

This is needed as the MPI grid needs to convert the location of the
source/receiver to its local coordinates. Doing this in the grid means
the multi use commands don't need to know about the MPI implementation

gprMax/grid/fdtd_grid.py

@@ -153,6 +153,21 @@ class FDTDGrid:
             self.pmls["thickness"]["ymax"] = int(thickness[4])
             self.pmls["thickness"]["zmax"] = int(thickness[5])
 
+    def add_source(self, source: Source):
+        if isinstance(source, VoltageSource):
+            self.voltagesources.append(source)
+        elif isinstance(source, HertzianDipole):
+            self.hertziandipoles.append(source)
+        elif isinstance(source, MagneticDipole):
+            self.magneticdipoles.append(source)
+        elif isinstance(source, TransmissionLine):
+            self.transmissionlines.append(source)
+        else:
+            raise TypeError(f"Source of type '{type(source)}' is unknown to gprMax")
+
+    def add_receiver(self, receiver: Rx):
+        self.rxs.append(receiver)
+
     def build(self) -> None:
         """Build the grid."""
 

gprMax/grid/mpi_grid.py

@@ -155,6 +155,16 @@ class MPIGrid(FDTDGrid):
         if self.has_neighbour(Dim.Z, Dir.POS):
             self.pmls["thickness"]["zmax"] = 0
 
+    def add_source(self, source: Source):
+        source.coord = self.global_to_local_coordinate(source.coord)
+        source.coordorigin = self.global_to_local_coordinate(source.coordorigin)
+        return super().add_source(source)
+
+    def add_receiver(self, receiver: Rx):
+        receiver.coord = self.global_to_local_coordinate(receiver.coord)
+        receiver.coordorigin = self.global_to_local_coordinate(receiver.coordorigin)
+        return super().add_receiver(receiver)
+
     def is_coordinator(self) -> bool:
         """Test if the current rank is the coordinator.
 

gprMax/user_objects/cmds_multiuse.py

@@ -441,7 +441,7 @@ class VoltageSource(RotatableMixin, GridUserObject):
         if uip.check_src_rx_point(discretised_point, self.params_str()):
             self._validate_parameters(grid)
             voltage_source = self._create_voltage_source(grid, discretised_point)
-            grid.voltagesources.append(voltage_source)
+            grid.add_source(voltage_source)
             self._log(grid, voltage_source)
 
 
@@ -591,7 +591,7 @@ class HertzianDipole(RotatableMixin, GridUserObject):
         if uip.check_src_rx_point(discretised_point, self.params_str()):
             self._validate_parameters(grid)
             hertzian_dipole = self._create_hertzian_dipole(grid, discretised_point)
-            grid.hertziandipoles.append(hertzian_dipole)
+            grid.add_source(hertzian_dipole)
             self._log(grid, hertzian_dipole)
 
 
@@ -645,7 +645,7 @@ class MagneticDipole(RotatableMixin, GridUserObject):
         if uip.check_src_rx_point(discretised_point, self.params_str()):
             self._validate_parameters(grid)
             magnetic_dipole = self._create_magnetic_dipole(grid, discretised_point)
-            grid.magneticdipoles.append(magnetic_dipole)
+            grid.add_source(magnetic_dipole)
             self._log(grid, magnetic_dipole)
 
     def _do_rotate(self, grid: FDTDGrid):
@@ -802,7 +802,7 @@ class TransmissionLine(RotatableMixin, GridUserObject):
         if uip.check_src_rx_point(discretised_point, self.params_str()):
             self._validate_parameters(grid)
             transmission_line = self._create_transmission_line(grid, discretised_point)
-            grid.transmissionlines.append(transmission_line)
+            grid.add_source(transmission_line)
             self._log(grid, transmission_line)
 
     def _validate_parameters(self, grid: FDTDGrid):
@@ -996,7 +996,7 @@ class Rx(RotatableMixin, GridUserObject):
 
         if uip.check_src_rx_point(discretised_point, self.params_str()):
             receiver = self._create_receiver(grid, discretised_point)
-            grid.rxs.append(receiver)
+            grid.add_receiver(receiver)
 
             p = uip.discretised_to_continuous(discretised_point)
             logger.info(