[plotter] correct the scaling for the particles plot

plotter.py

@@ -604,7 +604,15 @@ class Plotter(Aggregator, BaseProcessor):
 
         for i, plot_overlay in enumerate(overlays):
             if plot_overlay in self.overlays:
-                plot_overlay = self.overlays[plot_overlay]
+
+                if plot_overlay == "particles":
+                    plot_overlay = partial(
+                        self.overlays[plot_overlay],
+                        unit_space=unit_space,
+                        center_space=center_space,
+                    )
+                else:
+                    plot_overlay = self.overlays[plot_overlay]
 
             try:
                 plot_overlay(ax_los, im_extent, **overlays_kwargs[i])
@@ -698,7 +706,9 @@ class Plotter(Aggregator, BaseProcessor):
             **kwargs,
         )
 
-    def _overlay_particles(self, ax_los, im_extent, **kwargs):
+    def _overlay_particles(
+        self, ax_los, im_extent, unit_space=U.pc, center_space=False, **kwargs
+    ):
         """
         Add an overlay with particles data
         """
@@ -708,6 +718,7 @@ class Plotter(Aggregator, BaseProcessor):
         hdf5_parts = tables.open_file(filename, "r")
         part_pos = hdf5_parts.get_node("/data/pos").read()
         hdf5_parts.close()
+        unit_length = self.save.root._v_attrs["unit_length"]
 
         # index of the horizontal axis
         ih = self._ax_nb[self._axes_h[ax_los]]
@@ -718,9 +729,27 @@ class Plotter(Aggregator, BaseProcessor):
         part_h = part_pos[:, ih]
         part_v = part_pos[:, iv]
 
-        # Renormalize
-        part_h = im_extent[0] + (im_extent[1] - im_extent[0]) * part_h
-        part_v = im_extent[2] + (im_extent[3] - im_extent[2]) * part_v
+        if center_space:
+            ax_h = self._axes_h[ax_los]
+            ax_v = self._axes_v[ax_los]
+            center = self.save.root.maps._v_attrs.center
+            center_h = center[self._ax_nb[ax_h]]
+            center_v = center[self._ax_nb[ax_v]]
+            part_h -= center_h
+            part_v -= center_v
+
+        part_h *= unit_length.express(unit_space)
+        part_v *= unit_length.express(unit_space)
+
+        # Filter
+        mask = (
+            (im_extent[0] <= part_h)
+            & (part_h <= im_extent[1])
+            & (im_extent[2] <= part_v)
+            & (part_v <= im_extent[3])
+        )
+        part_h = part_h[mask]
+        part_v = part_v[mask]
 
         # Scatter plot
         plt.scatter(part_h, part_v, **kwargs)