properly init vector obj

Author: Licini

src/compas_viewer/scene/vectorobject.py

@@ -62,6 +62,9 @@ def _calculate_arrow_buffer_data(self):
 
         self._arrow_colors = [self.linecolor or self.viewer.config.linecolor] * len(self._arrow_vertices)
 
+    def _read_points_data(self) -> None:
+        pass
+
     def _read_lines_data(self) -> ShaderDataType:
         positions = self._arrow_vertices
         colors = self._arrow_colors
@@ -74,7 +77,9 @@ def _read_frontfaces_data(self) -> ShaderDataType:
         elements = self.ARROW_FACE_INDICES
         return positions, colors, elements
 
+    def _read_backfaces_data(self) -> None:
+        pass
+
     def init(self):
         self._calculate_arrow_buffer_data()
-        self._lines_data = self._read_lines_data() if self.show_lines else None
-        self._frontfaces_data = self._read_frontfaces_data() if self.show_faces else None
+        super().init()