Flex fluids have been deprecated in TDW. Please use Obi fluids instead.
In Flex simulations fluids are bodies of fluids while sources are fluids emitted from a source.
- Flex fluid and source actors are only supported on Windows.
- Flex particle output data is disabled if there are fluid or source actors in the scene.
Like all Flex simulations, fluid simulations require a Flex container. The parameters "viscosity", "adhesion", and "cohesion" control the fluid dynamics.
TDW includes pre-set values for various types of fluids. You can find these in the tdw.flex_data.fluid_type.FLUID_TYPES:
from tdw.flex_data.fluid_type import FLUID_TYPES
print(FLUID_TYPES.keys())
water = FLUID_TYPES["water"]
print(water.fluid_type)
print(water.adhesion)
print(water.viscosity)
print(water.cohesion)Output:
dict_keys(['water', 'ink', 'oil', 'honey', 'glycerin', 'chocolate'])
water
0
0.01
0.001
You can then use these parameters in create_flex_container:
from tdw.controller import Controller
from tdw.tdw_utils import TDWUtils
from tdw.flex_data.fluid_type import FLUID_TYPES
fluid = FLUID_TYPES["honey"]
c = Controller()
c.communicate([TDWUtils.create_empty_room(12, 12),
{'$type': 'convexify_proc_gen_room'},
{"$type": "create_flex_container",
"collision_distance": 0.04,
"static_friction": 0.1,
"dynamic_friction": 0.1,
"particle_friction": 0.1,
"viscocity": fluid.viscosity,
"adhesion": fluid.adhesion,
"cohesion": fluid.cohesion,
"radius": 0.1,
"fluid_rest": 0.05,
"damping": 0.01,
"substep_count": 5,
"iteration_count": 8,
"buoyancy": 1.0}])In this example, fluids are parameterized and randomly selected:
import random
from tdw.controller import Controller
from tdw.flex_data.fluid_type import FLUID_TYPES
class FlexFluids(Controller):
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.communicate(self.get_add_scene(scene_name="tdw_room"))
def trial(self, fluid_name: str) -> None:
fluid = FLUID_TYPES[fluid_name]
self.communicate([{"$type": "create_flex_container",
"collision_distance": 0.04,
"static_friction": 0.1,
"dynamic_friction": 0.1,
"particle_friction": 0.1,
"viscocity": fluid.viscosity,
"adhesion": fluid.adhesion,
"cohesion": fluid.cohesion,
"radius": 0.1,
"fluid_rest": 0.05,
"damping": 0.01,
"substep_count": 5,
"iteration_count": 8,
"buoyancy": 1.0}])
def run(self, num_trials: int) -> None:
for i in range(num_trials):
# Select a random fluid.
fluid_name = random.choice(FLUID_TYPES.keys())
self.trial(fluid_name=fluid_name)
self.communicate({"$type": "terminate"})
if __name__ == "__main__":
c = FlexFluids()
c.run(num_trials=15)A fluid actor requires a pre-defined fluid object: Load it via load_flex_fluid_from_resources. Make the fluid body a fluid actor via set_flex_fluid_actor. When using fluid actors, set the parameter "fluid_container" to True and set "fluid_type" to the name of the fluid in assign_flex_container.
You can optionally add a receptacle object, such as fluid_receptacle1x1, found in models_special.json. It does not need to be a Flex-enabled object.
This example adds a random fluid to each trial:
import random
from tdw.controller import Controller
from tdw.tdw_utils import TDWUtils
from tdw.flex_data.fluid_type import FLUID_TYPES
class FlexFluids(Controller):
"""
Generate fluid simulation trials with random fluids.
"""
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)
# Create a scene and add a camera.
commands = [self.get_add_scene(scene_name="tdw_room")]
commands.extend(TDWUtils.create_avatar(position={"x": -3.75, "y": 1.5, "z": -0.5},
look_at={"x": 0, "y": 0, "z": 0},
avatar_id="a"))
self.communicate(commands)
def trial(self, fluid_name: str) -> None:
fluid = FLUID_TYPES[fluid_name]
receptacle_id = self.get_unique_id()
fluid_id = self.get_unique_id()
# Create a Flex fluid container.
# Add a receptacle and a fluid object.
self.communicate([{"$type": "create_flex_container",
"collision_distance": 0.04,
"static_friction": 0.1,
"dynamic_friction": 0.1,
"particle_friction": 0.1,
"viscocity": fluid.viscosity,
"adhesion": fluid.adhesion,
"cohesion": fluid.cohesion,
"radius": 0.1,
"fluid_rest": 0.05,
"damping": 0.01,
"substep_count": 5,
"iteration_count": 8,
"buoyancy": 1.0},
self.get_add_object(model_name="fluid_receptacle1x1",
object_id=receptacle_id,
position={"x": -0.35, "y": 0, "z": 0},
rotation={"x": 0, "y": 0, "z": 0},
library="models_special.json"),
{"$type": "scale_object",
"id": receptacle_id,
"scale_factor": {"x": 2.0, "y": 2.0, "z": 2.0}},
{"$type": "set_kinematic_state",
"id": receptacle_id,
"is_kinematic": True,
"use_gravity": False},
{"$type": "load_flex_fluid_from_resources",
"id": fluid_id,
"orientation": {"x": 0, "y": 0, "z": 0},
"position": {"x": -0.35, "y": 1.0, "z": 0}},
{"$type": "set_flex_fluid_actor",
"id": fluid_id,
"mass_scale": 1.0,
"particle_spacing": 0.05},
{"$type": "assign_flex_container",
"id": fluid_id,
"container_id": 0,
"fluid_container": True,
"fluid_type": fluid_name}])
# Let the fluid move.
for i in range(200):
self.communicate([])
# Reset the scene.
self.communicate([{"$type": "destroy_flex_container"},
{"$type": "destroy_object",
"id": receptacle_id},
{"$type": "destroy_flex_object",
"id": fluid_id}])
def run(self, num_trials: int) -> None:
for i in range(num_trials):
# Select a random fluid.
fluid_keys = list(FLUID_TYPES.keys())
fluid_name = random.choice(fluid_keys)
self.trial(fluid_name=fluid_name)
self.communicate({"$type": "terminate"})
if __name__ == "__main__":
c = FlexFluids()
c.run(num_trials=15)Result:
Note: Each trial ends with three commands: destroy_flex_container, destroy_object, and destroy_flex_object. A document later in this tutorial will explain in more depth how to reset a Flex scene. The command destroy_object is used for the receptacle because it isn't a Flex object.
A fluid source actor object requires at least two commands:
load_flex_fluid_source_from_resourcesThis will instantiate a model stored within the TDW build as the fluid source.set_flex_fluid_source_actorThis makes the object a fluid source actor.
Just like fluid actors, you can use fluid types to define fluid parameters. When using fluid source actors, set the parameter "fluid_container" to True and set "fluid_type" to the name of the fluid in assign_flex_container.
from tdw.controller import Controller
from tdw.tdw_utils import TDWUtils
from tdw.flex_data.fluid_type import FLUID_TYPES
c = Controller()
fluid = FLUID_TYPES["water"]
fluid_id = c.get_unique_id()
# Load the scene. Create a Flex container.
# Load the fluid source object and scale it.
# Create the fluid source actor, assign its container and set the scale to a reasonable size for a water jet.
commands = [c.get_add_scene(scene_name="tdw_room"),
{"$type": "create_flex_container",
"collision_distance": 0.05,
"static_friction": 0.1,
"dynamic_friction": 0.1,
"particle_friction": 0.1,
"solid_rest": 0.1,
"fluid_rest": 0.095,
"viscocity": fluid.viscosity,
"cohesion": fluid.cohesion,
"adhesion": fluid.adhesion,
"surface_tension": 0.01,
"radius": 0.25,
"damping": 0,
"substep_count": 2,
"iteration_count": 5,
"buoyancy": 1.0,
"anisotropy_scale": 1.5,
"max_particles": 15000,
"max_neighbors": 200},
{"$type": "load_flex_fluid_source_from_resources",
"id": fluid_id,
"orientation": {"x": 44, "y": 0, "z": 0},
"position": {"x": 0, "y": 1.0, "z": 0}},
{"$type": "scale_object",
"id": fluid_id,
"scale_factor": {"x": 0.4, "y": 0.4, "z": 1}},
{"$type": "set_flex_fluid_source_actor",
"id": fluid_id,
"mass_scale": 1.0,
"start_speed": 5.0,
"lifetime": 3.0,
"mesh_tesselation": 2},
{"$type": "assign_flex_container",
"id": fluid_id,
"container_id": 0,
"fluid_container": True},
{"$type": "set_time_step",
"time_step": 0.02}]
# Add an avatar.
commands.extend(TDWUtils.create_avatar(position={"x": 3.6, "y": 1.8, "z": 1.3}, look_at={"x": 0, "y": 1.35, "z": -2}))
c.communicate(commands)
for i in range(200):
c.communicate([])
c.communicate({"$type": "terminate"})Result:
Read the API documentation for a full list of parameters for set_flex_fluid_actor and set_flex_fluid_source_actor.
In almost all cases, you should use the default values; the most important values to adjust are in create_flex_container (see above example).
Next: Move, rotate, and scale Flex objects
Example controllers:
- In the TDW repo:
- tdw_physics includes a fluid simulation:
- submerging.py Drop ball objects of increasing mass into afluid.
Command API: