PyBox2D

2.3.10 verified Fri May 01 auth: no python maintenance

Python bindings for Box2D, a 2D physics engine. Version 2.3.10 is the latest. Releases are infrequent; the library is stable but in maintenance mode.

pip install box2d

Common errors

error ModuleNotFoundError: No module named 'box2d' ↓

cause Importing from 'box2d' (lowercase) but the correct module is 'Box2D'.

fix

from Box2D import ...

error AttributeError: module 'Box2D' has no attribute 'b2World' ↓

cause Usually due to a broken installation or mismatched package versions; also can happen if importing from 'Box2D' but the library is not properly installed.

fix

Reinstall via 'pip install --upgrade box2d' and verify import using 'import Box2D; print(dir(Box2D))'.

Warnings

gotcha The import module is 'Box2D' (capital B and D), not 'box2d' (lowercase). The PyPI package name is 'box2d' but the module name uses CamelCase. ↓

fix Use 'from Box2D import ...' instead of 'from box2d import ...'.

deprecated Python 2 is no longer supported. Ensure you are using Python 3. ↓

fix Use Python 3.6 or newer.

gotcha Setting body position using the 'position' attribute after creation may not work; use SetTransform() instead. ↓

fix Use body.position.Set(x, y) before creation or body.SetTransform(b2Vec2(x,y), angle) after creation.

Imports

Box2D
```
from Box2D import b2World
```
The top-level module is 'Box2D' (capital B, capital D).
b2World
wrong
```
from box2d import b2World
```
correct
```
from Box2D import b2World
```
Package name is 'box2d' (lowercase), but the module is 'Box2D' (capital letters).

Quickstart

Creates a simple falling circle simulation.

from Box2D import b2World, b2Vec2, b2BodyDef, b2_dynamicBody, b2CircleShape, b2FixtureDef
import math

world = b2World(gravity=b2Vec2(0, -10))
body_def = b2BodyDef()
body_def.type = b2_dynamicBody
body_def.position.Set(0, 10)
body = world.CreateBody(body_def)
circle = b2CircleShape(radius=1)
fixture_def = b2FixtureDef(shape=circle, density=1, friction=0.3)
body.CreateFixture(fixture_def)

for i in range(60):
    world.Step(1/60, 6, 2)
    print(body.position.y)