Simulators

Overview

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, ig_scene}: import the scene into PyBullet by calling scene.load, and then import it into MeshRenderer by calling self.renderer.add_instance. If InteractiveIndoorScene is imported using import_ig_scene, all objects in the scene are also imported.

• 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: igibson/render/viewer.py. Notably, you can press h in the ExternalView window to show the help menu for mouse/keyboard control.

Most of the code can be found here: igibson/simulator.py.

Examples

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

from igibson.robots.turtlebot_robot import Turtlebot
from igibson.simulator import Simulator
from igibson.scenes.gibson_indoor_scene import StaticIndoorScene
from igibson.objects.ycb_object import YCBObject
from igibson.utils.utils import parse_config
from igibson.render.mesh_renderer.mesh_renderer_settings import MeshRendererSettings
import numpy as np
from igibson.render.profiler import Profiler
from IPython import embed


def main():
    config = parse_config('../configs/turtlebot_demo.yaml')
    settings = MeshRendererSettings(enable_shadow=False, msaa=False)
    s = Simulator(mode='gui', image_width=256,
                  image_height=256, rendering_settings=settings)

    scene = StaticIndoorScene('Rs',
                              build_graph=True,
                              pybullet_load_texture=True)
    s.import_scene(scene)
    turtlebot = Turtlebot(config)
    s.import_robot(turtlebot)

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

    print(s.renderer.instances)

    for i in range(10000):
        with Profiler('Simulator step'):
            turtlebot.apply_action([0.1, 0.1])
            s.step()
            rgb = s.renderer.render_robot_cameras(modes=('rgb'))
    s.disconnect()


if __name__ == '__main__':
    main()