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bt ​

Canonical Import ​

fennel
(local bt (require :bt))

Source Files ​

  • src/lua_physics.cpp
  • src/physics.h

What It Provides ​

bt exposes the Bullet-backed physics binding used by Space for rigid bodies, collision shapes, dynamics worlds, constraints, vehicles, and runtime physics integration. physics is a search alias for this canonical bt module, not an importable module page.

API Summary ​

  • Math and transforms: Scalar, Vector3, Quaternion, and Transform.
  • Collision shapes and meshes: TriangleMesh, BvhTriangleMeshShape, HeightfieldTerrainShape, StaticPlaneShape, BoxShape, SphereShape, and shared CollisionShape methods.
  • Bodies and motion: DefaultMotionState, RigidBodyConstructionInfo, RigidBody, CollisionObject, and activation/collision flag constants.
  • Worlds and setup: DefaultCollisionConfiguration, CollisionDispatcher, DbvtBroadphase, SequentialImpulseConstraintSolver, DiscreteDynamicsWorld, and SoftRigidDynamicsWorld.
  • Constraints and vehicles: Point2PointConstraint, VehicleTuning, DefaultVehicleRaycaster, and RaycastVehicle.
  • Physics exposes engine-owned world helpers such as setGravity, addRigidBody, removeRigidBody, updateSingleAabb, syncMovedRigidBody, addAction, removeAction, addConstraint, removeConstraint, getNumConstraints, getWorld, and update.

Examples ​

fennel
(local bt (require :bt))

(local shape (bt.BoxShape (bt.Vector3 0.5 0.5 0.5)))
(local transform (bt.Transform))
(transform:setIdentity)
(transform:setOrigin (bt.Vector3 0 5 0))
(local motion (bt.DefaultMotionState transform))
(local info (bt.RigidBodyConstructionInfo 1.0 motion shape (bt.Vector3 0 0 0)))
(local body (bt.RigidBody info))

Errors and Platform Notes ​

Constructors validate required pointers and dimensions. For example, heightfield width/length must be greater than 1 and the heights table length must equal width * length; Point2PointConstraint requires a rigid body. Manage object lifetimes carefully because Bullet worlds and shapes may hold native pointers.

Aliases and Search Terms ​

Search terms: physics, Bullet, bt, rigid body, collision shape, dynamics world, constraint, vehicle, heightfield.