Skip to content

Latest commit

 

History

History
89 lines (70 loc) · 3.73 KB

output_data.md

File metadata and controls

89 lines (70 loc) · 3.73 KB
Raw
Physics (Flex)

FlexParticles output data

Flex simulations work by affecting particle field representations of objects in the scene. In TDW, it's possible to receive Flex particle data via send_flex_particles, which returns FlexParticles output data:

from tdw.controller import Controller
from tdw.tdw_utils import TDWUtils
from tdw.output_data import OutputData, FlexParticles

c = Controller()
object_id = c.get_unique_id()
resp = c.communicate([TDWUtils.create_empty_room(12, 12),
                      {"$type": "convexify_proc_gen_room"},
                      {"$type": "create_flex_container"},
                      c.get_add_object(model_name="cube",
                                       library="models_flex.json",
                                       object_id=object_id),
                      {"$type": "set_flex_solid_actor",
                       "id": object_id,
                       "mass_scale": 5,
                       "particle_spacing": 0.125},
                      {"$type": "assign_flex_container",
                       "id": object_id,
                       "container_id": 0},
                      {"$type": "send_flex_particles"}])
for i in range(len(resp) - 1):
    r_id = OutputData.get_data_type_id(resp[i])
    if r_id == "flex":
        flex = FlexParticles(resp[i])
        for j in range(flex.get_num_objects()):
            print("Object ID", flex.get_id(j))
            print("Particles\n", flex.get_particles(j))
            print("Velocities\n", flex.get_velocities(j))

Output:

Object ID 5785380
Particles
 [[-0.4375      0.06184745 -0.4375      0.2       ]
 [-0.4375      0.06184745 -0.3125      0.2       ]
 [-0.4375      0.06184745 -0.1875      0.2       ]
 ...
 [ 0.4375      0.93684745  0.1875      0.2       ]
 [ 0.4375      0.93684745  0.3125      0.2       ]
 [ 0.4375      0.93684745  0.4375      0.2       ]]
Velocities
 [[ 0.         -0.09745845  0.        ]
 [ 0.         -0.09745845  0.        ]
 [ 0.         -0.09745845  0.        ]
 ...
 [ 0.         -0.09744954  0.        ]
 [ 0.         -0.09744954  0.        ]
 [ 0.         -0.09744954  0.        ]]
  • flex.get_particles(j) returns a numpy array of particles. The first three elements are the particle's (x, y, z) positional coordinates. The fourth element is the particle's inverse mass.
  • flex.get_velocities(j) returns a numpy array of (x, y, z) particle velocities.
  • The particle ID is the index of the particle in either of the arrays.

FlexParticles data can be useful for analyzing the physics state of the scene and for applying forces to Flex objects.

As noted in the previous document, FlexParticle output data isn't available if the simulation contains a fluid or source actor.

Next: Apply forces to Flex objects

Return to the README

Example controllers:

  • In the TDW repo:
    • flex_particles.py Minimal example of how to receive FlexParticle output data.
    • chair.py An example of a soft-body chair that returns FlexParticle data.
  • tdw_physics includes a FlexDataset abstract class controller that can be used to generate datasets of Flex particle data.

Command API:

Output Data: