Line renderers are most useful for visualizing object motion. If you haven't done so already, we recommend you read the Physics (PhysX) tutorial.
Line renderers are non-physics 3D lines in a scene. They can be added from existing data as well as adjusted at runtime.
In this example, we'll run a series of "trials". In each trial, an object is added to the scene, as well as a line renderer, which is added by sending add_line_renderer. Using an ObjectManager, the trial will run until the object stops moving. At every frame, the controller will add a new point to the line renderer by sending add_points_to_line_renderer. At the end of the trial, the object and line renderer are removed by sending destroy_object and remove_line_renderer, respectively.
from typing import Dict
from tdw.controller import Controller
from tdw.tdw_utils import TDWUtils
from tdw.add_ons.third_person_camera import ThirdPersonCamera
from tdw.add_ons.object_manager import ObjectManager
class LineRenderer(Controller):
"""
Run a series of trials. In each trial, an object is dropped and its path is renderered as a 3D line.
"""
def __init__(self, port: int = 1071, check_version: bool = True, launch_build: bool = True):
super().__init__(port=port, check_version=check_version, launch_build=launch_build)
self.camera: ThirdPersonCamera = ThirdPersonCamera(avatar_id="a",
position={"x": 2.88, "y": 6.34, "z": -2.69},
look_at={"x": 0, "y": 0, "z": 0})
self.object_manager: ObjectManager = ObjectManager(transforms=False, rigidbodies=True, bounds=True)
self.add_ons.extend([self.camera, self.object_manager])
self.communicate(TDWUtils.create_empty_room(12, 12))
def trial(self, model_name: str, rotation: Dict[str, float], force: Dict[str, float]) -> None:
self.object_manager.reset()
# Add the object.
object_id = Controller.get_unique_id()
position = {"x": 0, "y": 3, "z": 0}
commands = Controller.get_add_physics_object(model_name=model_name,
object_id=object_id,
position=position,
rotation=rotation,
library="models_core.json")
# Apply a force to the object.
commands.append({"$type": "apply_force_to_object",
"id": object_id,
"force": force})
# Add the line.
line_id = Controller.get_unique_id()
commands.append({"$type": "add_line_renderer",
"id": line_id,
"points": [position, position],
"start_color": {"r": 0.6, "g": 0, "b": 0.2, "a": 1},
"end_color": {"r": 0, "g": 0.8, "b": 0.3, "a": 1},
"start_width": 0.2,
"end_width": 0.2,
"loop": False,
"position": {"x": 0, "y": 0, "z": 0}})
self.communicate(commands)
# Wait until the object stops moving.
while not self.object_manager.rigidbodies[object_id].sleeping:
# Add a line point at the object's position.
self.communicate({"$type": "add_points_to_line_renderer",
"id": line_id,
"points": [TDWUtils.array_to_vector3(self.object_manager.bounds[object_id].center)]})
# Clear the scene.
self.communicate([{"$type": "destroy_object",
"id": object_id},
{"$type": "destroy_line_renderer",
"id": line_id}])
def run(self) -> None:
self.trial(model_name="iron_box", rotation={"x": 5, "y": 40, "z": 30}, force={"x": 0.5, "y": 1.5, "z": 0})
self.trial(model_name="iron_box", rotation={"x": 5, "y": 40, "z": 30}, force={"x": 1.5, "y": 3.5, "z": 0})
self.communicate({"$type": "terminate"})
if __name__ == "__main__":
c = LineRenderer()
c.run()Result:
Whenever possible, you should set the "points" parameter of add_line_renderer rather than sending add_points_to_line_renderer; these two commands are handled differently on the backend, with add_line_renderer being the faster implementation. This isn't applicable in the above example because the goal is to extend the line at runtime, but the difference can be significant when loading a line from saved data.
For lines with many vertices, you may want to consider sending the command simplify_line_renderer which will remove intermediate points based on a "tolerance" value. What this value actually means is defined by the Unity Engine and not well documented; in practice, values between 0 and 0.01 seem to be adequate.
This example is the same as the previous example except that we send simplify_line_renderer with a tolerance value of 0.01:
from typing import Dict
from tdw.controller import Controller
from tdw.tdw_utils import TDWUtils
from tdw.add_ons.third_person_camera import ThirdPersonCamera
from tdw.add_ons.object_manager import ObjectManager
class LineRenderer(Controller):
"""
Run a series of trials. In each trial, an object is dropped and its path is renderered as a 3D line.
"""
def __init__(self, port: int = 1071, check_version: bool = True, launch_build: bool = True):
super().__init__(port=port, check_version=check_version, launch_build=launch_build)
self.camera: ThirdPersonCamera = ThirdPersonCamera(avatar_id="a",
position={"x": 2.88, "y": 6.34, "z": -2.69},
look_at={"x": 0, "y": 0, "z": 0})
self.object_manager: ObjectManager = ObjectManager(transforms=False, rigidbodies=True, bounds=True)
self.add_ons.extend([self.camera, self.object_manager])
self.communicate(TDWUtils.create_empty_room(12, 12))
def trial(self, model_name: str, rotation: Dict[str, float], force: Dict[str, float]) -> None:
self.object_manager.reset()
# Add the object.
object_id = Controller.get_unique_id()
position = {"x": 0, "y": 3, "z": 0}
commands = Controller.get_add_physics_object(model_name=model_name,
object_id=object_id,
position=position,
rotation=rotation,
library="models_core.json")
# Apply a force to the object.
commands.append({"$type": "apply_force_to_object",
"id": object_id,
"force": force})
# Add the line.
line_id = Controller.get_unique_id()
commands.append({"$type": "add_line_renderer",
"id": line_id,
"points": [position, position],
"start_color": {"r": 0.6, "g": 0, "b": 0.2, "a": 1},
"end_color": {"r": 0, "g": 0.8, "b": 0.3, "a": 1},
"start_width": 0.2,
"end_width": 0.2,
"loop": False,
"position": {"x": 0, "y": 0, "z": 0}})
self.communicate(commands)
# Wait until the object stops moving.
while not self.object_manager.rigidbodies[object_id].sleeping:
# Add a line point at the object's position.
self.communicate([{"$type": "add_points_to_line_renderer",
"id": line_id,
"points": [TDWUtils.array_to_vector3(self.object_manager.bounds[object_id].center)]},
{"$type": "simplify_line_renderer",
"id": line_id,
"tolerance": 0.01}])
# Clear the scene.
self.communicate([{"$type": "destroy_object",
"id": object_id},
{"$type": "destroy_line_renderer",
"id": line_id}])
def run(self) -> None:
self.trial(model_name="iron_box", rotation={"x": 5, "y": 40, "z": 30}, force={"x": 0.5, "y": 1.5, "z": 0})
self.trial(model_name="iron_box", rotation={"x": 5, "y": 40, "z": 30}, force={"x": 1.5, "y": 3.5, "z": 0})
self.communicate({"$type": "terminate"})
if __name__ == "__main__":
c = LineRenderer()
c.run()Result:
Remove points on the line by sending remove_points_from_line_renderer.
Next: Textured quads
Example controllers:
- line_renderer.py Run a series of trials. In each trial, an object is dropped and its path is renderered as a 3D line.
Command API: