Graphics

Environment rendering is done with pygame, which must be installed separately.

A window is created at the first call of env.render(). Its dimensions can be configured:

env = gym.make("roundabout-v0")
env.configure({
    "screen_width": 640,
    "screen_height": 480
})
env.reset()
env.render()

World surface

The simulation is rendered in a RoadSurface pygame surface, which defines the location and zoom of the rendered location. By default, the rendered area is always centered on the ego-vehicle. Its initial scale and offset can be set with the "scaling" and "centering_position" configurations, and can also be updated during simulation using the O,L keys and K,M keys, respectively.

Scene graphics

  • Roads are rendered in the RoadGraphics class.

  • Vehicles are rendered in the VehicleGraphics class.

API

class highway_env.envs.common.graphics.EnvViewer(env: AbstractEnv, config: Optional[dict] = None)[source]

A viewer to render a highway driving environment.

set_agent_display(agent_display: Callable) None[source]

Set a display callback provided by an agent

So that they can render their behaviour on a dedicated agent surface, or even on the simulation surface.

Parameters

agent_display – a callback provided by the agent to display on surfaces

set_agent_action_sequence(actions: List[Action]) None[source]

Set the sequence of actions chosen by the agent, so that it can be displayed

Parameters

actions – list of action, following the env’s action space specification

handle_events() None[source]

Handle pygame events by forwarding them to the display and environment vehicle.

display() None[source]

Display the road and vehicles on a pygame window.

get_image() numpy.ndarray[source]

The rendered image as a rgb array.

OpenAI gym’s channel convention is H x W x C

window_position() numpy.ndarray[source]

the world position of the center of the displayed window.

close() None[source]

Close the pygame window.

class highway_env.road.graphics.WorldSurface(size: Tuple[int, int], flags: object, surf: pygame.Surface)[source]

A pygame Surface implementing a local coordinate system so that we can move and zoom in the displayed area.

pix(length: float) int[source]

Convert a distance [m] to pixels [px].

Parameters

length – the input distance [m]

Returns

the corresponding size [px]

pos2pix(x: float, y: float) Tuple[int, int][source]

Convert two world coordinates [m] into a position in the surface [px]

Parameters
  • x – x world coordinate [m]

  • y – y world coordinate [m]

Returns

the coordinates of the corresponding pixel [px]

vec2pix(vec: Union[Tuple[float, float], numpy.ndarray]) Tuple[int, int][source]

Convert a world position [m] into a position in the surface [px].

Parameters

vec – a world position [m]

Returns

the coordinates of the corresponding pixel [px]

is_visible(vec: Union[Tuple[float, float], numpy.ndarray], margin: int = 50) bool[source]

Is a position visible in the surface? :param vec: a position :param margin: margins around the frame to test for visibility :return: whether the position is visible

move_display_window_to(position: Union[Tuple[float, float], numpy.ndarray]) None[source]

Set the origin of the displayed area to center on a given world position.

Parameters

position – a world position [m]

handle_event(event: Event) None[source]

Handle pygame events for moving and zooming in the displayed area.

Parameters

event – a pygame event

class highway_env.road.graphics.LaneGraphics[source]

A visualization of a lane.

STRIPE_SPACING: float = 4.33

Offset between stripes [m]

STRIPE_LENGTH: float = 3

Length of a stripe [m]

STRIPE_WIDTH: float = 0.3

Width of a stripe [m]

classmethod display(lane: highway_env.road.lane.AbstractLane, surface: highway_env.road.graphics.WorldSurface) None[source]

Display a lane on a surface.

Parameters
  • lane – the lane to be displayed

  • surface – the pygame surface

classmethod striped_line(lane: highway_env.road.lane.AbstractLane, surface: highway_env.road.graphics.WorldSurface, stripes_count: int, longitudinal: float, side: int) None[source]

Draw a striped line on one side of a lane, on a surface.

Parameters
  • lane – the lane

  • surface – the pygame surface

  • stripes_count – the number of stripes to draw

  • longitudinal – the longitudinal position of the first stripe [m]

  • side – which side of the road to draw [0:left, 1:right]

classmethod continuous_curve(lane: highway_env.road.lane.AbstractLane, surface: highway_env.road.graphics.WorldSurface, stripes_count: int, longitudinal: float, side: int) None[source]

Draw a striped line on one side of a lane, on a surface.

Parameters
  • lane – the lane

  • surface – the pygame surface

  • stripes_count – the number of stripes to draw

  • longitudinal – the longitudinal position of the first stripe [m]

  • side – which side of the road to draw [0:left, 1:right]

classmethod continuous_line(lane: highway_env.road.lane.AbstractLane, surface: highway_env.road.graphics.WorldSurface, stripes_count: int, longitudinal: float, side: int) None[source]

Draw a continuous line on one side of a lane, on a surface.

Parameters
  • lane – the lane

  • surface – the pygame surface

  • stripes_count – the number of stripes that would be drawn if the line was striped

  • longitudinal – the longitudinal position of the start of the line [m]

  • side – which side of the road to draw [0:left, 1:right]

classmethod draw_stripes(lane: highway_env.road.lane.AbstractLane, surface: highway_env.road.graphics.WorldSurface, starts: List[float], ends: List[float], lats: List[float]) None[source]

Draw a set of stripes along a lane.

Parameters
  • lane – the lane

  • surface – the surface to draw on

  • starts – a list of starting longitudinal positions for each stripe [m]

  • ends – a list of ending longitudinal positions for each stripe [m]

  • lats – a list of lateral positions for each stripe [m]

class highway_env.road.graphics.RoadGraphics[source]

A visualization of a road lanes and vehicles.

static display(road: highway_env.road.road.Road, surface: highway_env.road.graphics.WorldSurface) None[source]

Display the road lanes on a surface.

Parameters
  • road – the road to be displayed

  • surface – the pygame surface

static display_traffic(road: highway_env.road.road.Road, surface: highway_env.road.graphics.WorldSurface, simulation_frequency: int = 15, offscreen: bool = False) None[source]

Display the road vehicles on a surface.

Parameters
  • road – the road to be displayed

  • surface – the pygame surface

  • simulation_frequency – simulation frequency

  • offscreen – render without displaying on a screen

static display_road_objects(road: highway_env.road.road.Road, surface: highway_env.road.graphics.WorldSurface, offscreen: bool = False) None[source]

Display the road objects on a surface.

Parameters
  • road – the road to be displayed

  • surface – the pygame surface

  • offscreen – whether the rendering should be done offscreen or not

class highway_env.road.graphics.RoadObjectGraphics[source]

A visualization of objects on the road.

classmethod display(object_: RoadObject, surface: highway_env.road.graphics.WorldSurface, transparent: bool = False, offscreen: bool = False)[source]

Display a road objects on a pygame surface.

The objects is represented as a colored rotated rectangle

Parameters
  • object – the vehicle to be drawn

  • surface – the surface to draw the object on

  • transparent – whether the object should be drawn slightly transparent

  • offscreen – whether the rendering should be done offscreen or not

static blit_rotate(surf: pygame.Surface, image: pygame.Surface, pos: Union[numpy.ndarray, Sequence[float]], angle: float, origin_pos: Optional[Union[numpy.ndarray, Sequence[float]]] = None, show_rect: bool = False) None[source]

Many thanks to https://stackoverflow.com/a/54714144.