Physics

PhysicsWorld is an entity that simulates AABB collisions with gravity.

world = bf.PhysicsWorld(gravity=(0, 900))
world.add_layer("terrain")
world.add_layer("actors")
world.add_static("terrain", ground)
world.add_dynamic("actors", player)
world.set_layers_collide("actors", "terrain")
scene.add(world)

Physics layers ≠ scene layers

CollisionLayer names group bodies for collision filtering. They are unrelated to the old scene render layers.

Setup

• add_layer(name)
• add_static(layer, *entities) / add_dynamic(layer, *entities)
• set_layers_collide(a, b, collide=True)
• set_collision_callback(a, b, callback)
• enable_spatial_hash(cell_size=64)
• track_entity(entity)

Queries

• raycast(origin, direction, max_distance=..., *layers)
• query_rect(rect, layers=None)
• query_point(point, layers=None)
• check_collision(a, b) → Collision

Helpers: check_aabb, get_overlap, find_collisions.

DynamicEntity

Movable bodies usually inherit DynamicEntity:

• velocity, mass, restitution, grounded
• set_velocity(x, y), apply_impulse(x, y), move_by_velocity(dt)
• Override on_collideX, on_collideY, on_land for custom response