Fix placement of objects in plater

plater.py

@@ -300,8 +300,8 @@ class StlPlater(Plater):
                     maxz = j[2]
         model.dims = [minx, maxx, miny, maxy, minz, maxz]
         self.add_model(name, model)
-        model.centeroffset = [(maxx - minx) / 2,
-                              (maxy - miny) / 2,
+        model.centeroffset = [-(model.dims[1] + model.dims[0]) / 2,
+                              -(model.dims[3] + model.dims[2]) / 2,
                               0]
         self.s.drawmodel(model, 2)
 

printrun/objectplater.py

@@ -164,8 +164,9 @@ class Plater(wx.Frame):
                            center = packer.Vector2(centerx, centery))
             for rect in rects:
                 i = rect.data
-                self.models[i].offsets[0] = rect.position.x
-                self.models[i].offsets[1] = rect.position.y
+                position = rect.center()
+                self.models[i].offsets[0] = position.x
+                self.models[i].offsets[1] = position.y
         except ImportError:
             bedsize = self.build_dimensions[0:3]
             cursor = [0, 0, 0]