Added spawn_circuit boolean to sim.launch

seat_car_gazebo/launch/sim.launch

@@ -2,9 +2,10 @@
 <launch>
 
   <arg name="circuit"  default="full"/>
+  <arg name="spawn_circuit" default="true"/>
   <arg name="name"  default="seat_car"/>
   <arg name="model" default="car"/>
-  <arg name="world" default="empty"/>
+  <arg name="world" default="empty"/> <!-- empty, building -->
   <arg name="gazebo_gui" default="False"/>
   <arg name="car_x"    default="0.0"/>
   <arg name="car_y"    default="-0.2"/> <!--CW: -0.2, CCW: 0.2 -->
@@ -18,7 +19,7 @@
     <arg name="gui"   value="$(arg gazebo_gui)"/>
   </include>
   
-  <include file="$(find road_description)/launch/spawn_circuit.launch">
+  <include if="$(arg spawn_circuit)" file="$(find road_description)/launch/spawn_circuit.launch">
     <arg name="circuit" value="$(arg circuit)"/>
   </include>