Simulator maintains an instance of Renderer and PhysicsEngine and provides APIs to import Scene, Object and Robot into both of them and keep them synchronized at all time.

Some key functions are the following:

  • load: initialize PyBullet physics engine and MeshRenderer

  • import_scene: import the scene into PyBullet by calling scene.load, and then import it into MeshRenderer by calling self.renderer.add_instance. If the scene is interactive (is_interactive=True), all the objects in the scene will be imported as well.

  • import_{object, articulated_object, robot}: import the object, articulated object and robot into the simulator in a similar manner

  • sync: synchronize the poses of the dynamic objects (including the robots) between PyBullet and MeshRenderer. Specifically, it calls update_position for each object, in which it retrieve the object’s pose in PyBullet, and then update its pose accordingly in MeshRenderer.

If Simulator uses gui mode, by default it will also maintain a Viewer, which essentially is a virtual camera in the scene that can render images. More info about the Viewer can be found here: gibson2/core/render/

Most of the code can be found here: gibson2/core/


In this example, we import a BuildingScene, a Turtlebot, and ten YCBObject into the simulator. The code can be found here: examples/demo/

from gibson2.core.physics.robot_locomotors import Turtlebot
from gibson2.core.simulator import Simulator
from gibson2.core.physics.scene import BuildingScene
from gibson2.core.physics.interactive_objects import YCBObject
from gibson2.utils.utils import parse_config
import pybullet as p
import numpy as np
from gibson2.core.render.profiler import Profiler

def main():
    config = parse_config('../configs/turtlebot_demo.yaml')
    s = Simulator(mode='gui', image_width=512, image_height=512)
    scene = BuildingScene('Rs',
    turtlebot = Turtlebot(config)

    for _ in range(10):
        obj = YCBObject('003_cracker_box')
        obj.set_position_orientation(np.random.uniform(low=0, high=2, size=3), [0,0,0,1])

    for i in range(10000):
        with Profiler('Simulator step'):
            rgb = s.renderer.render_robot_cameras(modes=('rgb'))


if __name__ == '__main__':