.. note::
:class: sphx-glr-download-link-note
Click :ref:`here <sphx_glr_download_auto_examples_physics_using_pybullet_viz_brick_wall.py>` to download the full example code
.. rst-class:: sphx-glr-example-title
.. _sphx_glr_auto_examples_physics_using_pybullet_viz_brick_wall.py:
=====================
Brick Wall Simulation
=====================
This example simulation shows how to use pybullet to render physics simulations
in fury. In this example we specifically render a ball beign thrown at a brick
wall.
First some imports.
.. code-block:: default
import numpy as np
from fury import window, actor, ui, utils
import itertools
import pybullet as p
Next, we initialize a pybullet client to render the physics. We use `DIRECT`
mode to initialize pybullet without a GUI.
.. code-block:: default
p.connect(p.DIRECT)
Apply gravity to the scene. In pybullet all values are in SI units.
.. code-block:: default
p.setGravity(0, 0, -10)
We define some global parameters so that its easier for us to tweak the
tweak the simulation.
.. code-block:: default
# Ball Parameters
ball_radius = 0.3
ball_color = np.array([1, 0, 0])
ball_mass = 3
ball_position = np.array([2, 0, 1.5])
ball_orientation = np.array([0, 0, 0, 1])
# Base Plane Parameters
base_size = np.array([5, 5, 0.2])
base_color = np.array([1, 1, 1])
base_position = np.array([0, 0, -0.1])
base_orientation = np.array([0, 0, 0, 1])
# Wall Parameters
wall_height = 10
wall_width = 10
brick_mass = 0.5
brick_size = np.array([0.2, 0.4, 0.2])
Now we define the required parameters to render the Ball.
.. code-block:: default
# Ball actor
ball_actor = actor.sphere(centers=np.array([[0, 0, 0]]),
colors=ball_color,
radii=ball_radius)
# Collision shape for the ball.
ball_coll = p.createCollisionShape(p.GEOM_SPHERE,
radius=ball_radius)
# Creating a multi-body which will be tracked by pybullet.
ball = p.createMultiBody(baseMass=3,
baseCollisionShapeIndex=ball_coll,
basePosition=ball_position,
baseOrientation=ball_orientation)
# Change the dynamics of the ball by adding friction and restitution.
p.changeDynamics(ball, -1, lateralFriction=0.3, restitution=0.5)
Render a base plane to support the bricks.
.. code-block:: default
base_actor = actor.box(centers=np.array([[0, 0, 0]]),
directions=[0, 0, 0],
scales=base_size,
colors=base_color)
base_coll = p.createCollisionShape(p.GEOM_BOX,
halfExtents=base_size / 2)
# half of the actual size.
base = p.createMultiBody(
baseCollisionShapeIndex=base_coll,
basePosition=base_position,
baseOrientation=base_orientation)
p.changeDynamics(base, -1, lateralFriction=0.3, restitution=0.5)
Now we render the bricks. All the bricks are rendered by a single actor for
better performance.
.. code-block:: default
nb_bricks = wall_height * wall_width
brick_centers = np.zeros((nb_bricks, 3))
brick_directions = np.zeros((nb_bricks, 3))
brick_directions[:] = np.array([1.57, 0, 0])
brick_orns = np.zeros((nb_bricks, 4))
brick_sizes = np.zeros((nb_bricks, 3))
brick_sizes[:] = brick_size
brick_colors = np.random.rand(nb_bricks, 3)
brick_coll = p.createCollisionShape(p.GEOM_BOX,
halfExtents=brick_size / 2)
# We use this array to store the reference of brick objects in pybullet world.
bricks = np.zeros(nb_bricks, dtype=np.int8)
# Logic to position the bricks appropriately to form a wall.
i = 0
for k in range(wall_height):
for j in range(wall_width):
center_pos = np.array([-1, (j * 0.4) - 1.8, (0.2 * k) + 0.1])
brick_centers[i] = center_pos
brick_orns[i] = np.array([0, 0, 0, 1])
bricks[i] = p.createMultiBody(baseMass=brick_mass,
baseCollisionShapeIndex=brick_coll,
basePosition=center_pos,
baseOrientation=brick_orns[i])
p.changeDynamics(bricks[i], -1, lateralFriction=0.1, restitution=0.1)
i += 1
brick_actor = actor.box(centers=brick_centers,
directions=brick_directions,
scales=brick_sizes,
colors=brick_colors)
Now, we define a scene and add actors to it.
.. code-block:: default
scene = window.Scene()
scene.add(actor.axes())
scene.add(ball_actor)
scene.add(base_actor)
scene.add(brick_actor)
# Create show manager.
showm = window.ShowManager(scene,
size=(900, 768), reset_camera=False,
order_transparent=True)
showm.initialize()
# Counter iterator for tracking simulation steps.
counter = itertools.count()
# Variable for tracking applied force.
apply_force = True
Now, we define methods to sync objects between fury and Pybullet.
.. code-block:: default
# Get the position of base and set it.
base_pos, _ = p.getBasePositionAndOrientation(base)
base_actor.SetPosition(*base_pos)
# Do the same for ball.
ball_pos, _ = p.getBasePositionAndOrientation(ball)
ball_actor.SetPosition(*ball_pos)
# Calculate the vertices of the bricks.
vertices = utils.vertices_from_actor(brick_actor)
num_vertices = vertices.shape[0]
num_objects = brick_centers.shape[0]
sec = int(num_vertices / num_objects)
==============
Syncing Bricks
==============
Here, we perform three major steps to sync bricks accurately.
* Get the position and orientation of the bricks from pybullet.
* Calculate the Rotation Matrix.
- Get the difference in orientations (Quaternion).
- Generate the corresponding rotation matrix according to that difference.
- Reshape it in a 3x3 matrix.
* Perform calculations to get the required position and orientation.
* Update the position and orientation.
.. code-block:: default
def sync_brick(object_index, multibody):
pos, orn = p.getBasePositionAndOrientation(multibody)
rot_mat = np.reshape(
p.getMatrixFromQuaternion(
p.getDifferenceQuaternion(orn, brick_orns[object_index])),
(3, 3))
vertices[object_index * sec: object_index * sec + sec] = \
(vertices[object_index * sec: object_index * sec + sec] -
brick_centers[object_index]) @ rot_mat + pos
brick_centers[object_index] = pos
brick_orns[object_index] = orn
A simpler but inaccurate approach is used here to update the position and
orientation.
.. code-block:: default
def sync_actor(actor, multibody):
pos, orn = p.getBasePositionAndOrientation(multibody)
actor.SetPosition(*pos)
orn_deg = np.degrees(p.getEulerFromQuaternion(orn))
actor.SetOrientation(*orn_deg)
Here, we define a textblock to display the Avg. FPS and simulation steps.
.. code-block:: default
fpss = np.array([])
tb = ui.TextBlock2D(text="Avg. FPS: \nSim Steps: ", position=(0, 680),
font_size=30, color=(1, 0.5, 0))
scene.add(tb)
Set the camera for better visualization.
.. code-block:: default
scene.set_camera(position=(10.46, -8.13, 6.18),
focal_point=(0.0, 0.0, 0.79),
view_up=(-0.27, 0.26, 0.90))
Timer callback is created which is responsible for calling the sync and
simulation methods.
.. code-block:: default
# Create timer callback which will execute at each step of simulation.
def timer_callback(_obj, _event):
global apply_force, fpss
cnt = next(counter)
showm.render()
if cnt % 1 == 0:
fps = scene.frame_rate
fpss = np.append(fpss, fps)
tb.message = "Avg. FPS: " + str(np.round(np.mean(fpss), 0)) + \
"\nSim Steps: " + str(cnt)
# Get the position and orientation of the ball.
ball_pos, ball_orn = p.getBasePositionAndOrientation(ball)
# Apply force for 5 times for the first step of simulation.
if apply_force:
# Apply the force.
p.applyExternalForce(ball, -1,
forceObj=[-10000, 0, 0],
posObj=ball_pos,
flags=p.WORLD_FRAME)
apply_force = False
# Set position and orientation of the ball.
sync_actor(ball_actor, ball)
# Updating the position and orientation of each individual brick.
for idx, brick in enumerate(bricks):
sync_brick(idx, brick)
utils.update_actor(brick_actor)
# Simulate a step.
p.stepSimulation()
# Exit after 2000 steps of simulation.
if cnt == 130:
showm.exit()
# Add the timer callback to showmanager.
# Increasing the duration value will slow down the simulation.
showm.add_timer_callback(True, 1, timer_callback)
interactive = False
# start simulation
if interactive:
showm.start()
window.record(scene, out_path="viz_brick_wall.png", size=(900, 768))
.. image:: /auto_examples/physics_using_pybullet/images/sphx_glr_viz_brick_wall_001.png
:class: sphx-glr-single-img
.. rst-class:: sphx-glr-timing
**Total running time of the script:** ( 0 minutes 0.211 seconds)
.. _sphx_glr_download_auto_examples_physics_using_pybullet_viz_brick_wall.py:
.. only :: html
.. container:: sphx-glr-footer
:class: sphx-glr-footer-example
.. container:: sphx-glr-download
:download:`Download Python source code: viz_brick_wall.py <viz_brick_wall.py>`
.. container:: sphx-glr-download
:download:`Download Jupyter notebook: viz_brick_wall.ipynb <viz_brick_wall.ipynb>`
.. only:: html
.. rst-class:: sphx-glr-signature
`Gallery generated by Sphinx-Gallery <https://sphinx-gallery.github.io>`_