Weld Joint

Create weld joints

Uses:

• b2d.WeldJointDef

• b2d.WeldJoint

Imports

pyb2d is imported as b2d

import b2d
import numpy as np
import math

These imports are only needed for plotting. b2d.plot requires OpenCV to be installed!

import b2d.plot
import matplotlib.pyplot as plt

The first step with Box2D is the creation of the world. The world is parametrized by a gravity vector.

# the world
world = b2d.world(gravity=(0, -10))


bodies = []

# create  a static body as anchor
b = world.create_static_body(
    position=(0, 4), fixtures=b2d.fixture_def(shape=b2d.polygon_shape(box=[0.3, 0.5]))
)
bodies.append(b)

for i in range(10):
    b = world.create_dynamic_body(
        position=(i + 1.0, 4),
        fixtures=b2d.fixture_def(shape=b2d.polygon_shape(box=[0.3, 0.5]), density=0.1),
        linear_damping=2.5,
        angular_damping=2.5,
    )
    bodies.append(b)

for i in range(len(bodies) - 1):
    a = bodies[i]
    b = bodies[i + 1]
    world.create_weld_joint(
        a,
        b,
        local_anchor_a=(0.5, 0.5),
        local_anchor_b=(-0.5, 0.5),
        damping=0.1,
        reference_angle=0,
        stiffness=20,
    )
    world.create_weld_joint(
        a,
        b,
        local_anchor_a=(0.5, -0.5),
        local_anchor_b=(-0.5, -0.5),
        damping=0.1,
        reference_angle=0,
        stiffness=20,
    )


fig, ax, ani = b2d.plot.animate_world(world, world_margin=(10, 10))
ani
plt.show()

Once Loop Reflect

/home/runner/.local/lib/python3.10/site-packages/b2d/plot.py:128: UserWarning: You passed in an explicit save_count=73 which is being ignored in favor of frames=73.
  ani = animation.FuncAnimation(