Many of the techniques involved in resetting a non-Flex scene are the same as those for non-Flex TDW scenes. The main difference is which commands you need to send. If you haven't done so already, read this document regarding resetting a scene.
When resetting a Flex scene, be sure to clear Flex data from memory. Flex always leaks memory during a scene reset but these commands will leak much less memory:
- For each Flex object, you must send
destroy_flex_object. Send this instead ofdestroy_objectfor Flex. Send this even if you are unloading and reloading a scene. - After destroying all Flex objects in the scene, destroy all Flex containers with
destroy_flex_container. Send this even if you are unloading and reloading a scene.
This minimal example correctly resets a Flex scene. It runs a series of trials in which an object is dropped from a given height. After each trial, the controller saves the particle data as a .npy file and resets the scene:
import numpy as np
from typing import Tuple, List
from tdw.controller import Controller
from tdw.tdw_utils import TDWUtils
from tdw.output_data import OutputData, FlexParticles
from tdw.backend.paths import EXAMPLE_CONTROLLER_OUTPUT_PATH
class ResetScene(Controller):
"""
Minimal example of how to reset a Flex scene.
"""
def trial(self, model_name: str, mass: float, height: float) -> Tuple[np.ndarray, np.ndarray]:
"""
Drop an Flex object and record its particles.
"""
object_id = c.get_unique_id()
resp = self.communicate([{"$type": "create_flex_container"},
c.get_add_object(model_name=model_name,
library="models_flex.json",
object_id=object_id,
position={"x": 0, "y": height, "z": 0}),
{"$type": "set_flex_soft_actor",
"id": object_id,
'particle_spacing': 0.125,
'cluster_stiffness': 0.5,
"mass_scale": mass},
{"$type": "assign_flex_container",
"id": object_id,
"container_id": 0},
{"$type": "send_flex_particles",
"frequency": "always"}])
particles: List[np.ndarray] = list()
velocities: List[np.ndarray] = list()
# Let the object fall.
for i in range(250):
for j in range(len(resp) - 1):
r_id = OutputData.get_data_type_id(resp[j])
# Log the particle data on this frame.
if r_id == "flex":
flex = FlexParticles(resp[j])
for k in range(flex.get_num_objects()):
if flex.get_id(k) == object_id:
particles.append(flex.get_particles(k))
velocities.append(flex.get_velocities(k))
resp = self.communicate([])
# Reset the scene.
self.communicate([{"$type": "destroy_flex_object",
"id": object_id},
{"$type": "destroy_flex_container",
"id": 0}])
return np.array(particles), np.array(velocities)
def run(self) -> None:
"""
Run a series of trials.
"""
output_directory = EXAMPLE_CONTROLLER_OUTPUT_PATH.joinpath("reset_flex_scene")
if not output_directory.exists():
output_directory.mkdir(parents=True)
print(f"Particle data will be saved to: {output_directory}")
# Create the scene.
self.communicate([TDWUtils.create_empty_room(12, 12),
{"$type": "convexify_proc_gen_room"}])
i = 0
for model_name, height, mass in zip(["cube", "octahedron", "dumbbell"],
[1, 1.5, 1.78],
[5, 6, 2]):
particles, velocities = self.trial(model_name=model_name, height=height, mass=mass)
# Save the particle data.
np.save(str(output_directory.joinpath(f"particles_{i}").resolve()), np.array(particles))
np.save(str(output_directory.joinpath(f"velocities_{i}").resolve()), np.array(velocities))
i += 1
# End the simulation.
self.communicate({"$type": "terminate"})
if __name__ == "__main__":
c = ResetScene()
c.run()Next: Other Flex commands
Example controllers:
- reset_scene.py Minimal example of how to reset a Flex scene.
Command API: