Internals: Physics Interface

Initializing the State

void TS_BtInit()

initialize the physics state

Adding Physics Objects

struct TS_PhysicsObject

proxy representing a bullet physics-enabled object

Public Functions

TS_PhysicsObject(btCollisionShape *s, float mass = 0.0f, bool isKinematic = false, bool isTrigger = false, const btVector3 &initPos = btVector3(0, 0, 0), const btQuaternion &initRot = btQuaternion(0, 0, 1, 1))

construct the object

Parameters

  • s – bullet collision shape

  • mass – [optional] mass

  • isKinematic – [optional] is a kinematic object

  • isTrigger – [optional] is a trigger object

  • initPos – [optional] initial position in 3d space

  • initRot – [optional] initial quaternion

~TS_PhysicsObject()

destructor

btTransform getTransform()

access transforms

Returns

btTransform object

Public Members

btCollisionObject *cobj

internal bullet collision object

btCollisionShape *cshape

collision shape

btRigidBody *rbody

rigid body

btDefaultMotionState *dmstate

default motion state

void TS_BtAddRigidBox(int id, float size_x, float size_y, float size_z, float mass, float position_x, float position_y, float position_z, bool is_kinematic = false)

add a rigid, axis-aligned collision box to the state

Parameters

  • id – id of the newly created object

  • size_x – size along the x-dimension

  • size_y – size along the y-dimension

  • size_z – size along the z-dimension

  • mass – mass of the box

  • position_x – x-coordinate of the position of the box

  • position_y – y-coordinate of the position of the box

  • position_z – z-coordinate of the position of the box

  • is_kinematic – should the box be a kinematic object

void TS_BtAddStaticBox(int id, float size_x, float size_y, float size_z, float position_x, float position_y, float position_z)

add a static, axis-aligned collision box to the state

Parameters

  • id – id of the newly created object

  • size_x – size along the x-dimension

  • size_y – size along the y-dimension

  • size_z – size along the z-dimension

  • position_x – x-coordinate of the position of the box

  • position_y – y-coordinate of the position of the box

  • position_z – z-coordinate of the position of the box

void TS_BtAddTriggerBox(int id, float size_x, float size_y, float size_z, float position_x, float position_y, float position_z)

add a box-shaped trigger to the state

Parameters

  • id – id of the newly created object

  • size_x – size along the x-dimension

  • size_y – size along the y-dimension

  • size_z – size along the z-dimension

  • position_x – x-coordinate of the position of the box

  • position_y – y-coordinate of the position of the box

  • position_z – z-coordinate of the position of the box

void TS_BtRemovePhysicsObject(int id)

remove a physics object from the state

Parameters

id – id of the object

Setting the Position of an Object

struct TS_PositionInfo

positional information, describes point in 3D space

Public Members

float x

x-coordinate

float y

y-coordinate

float z

z-coodrinate

TS_PositionInfo TS_BtGetPosition(int id)

get the position of an object

Returns

TS_PositionInfo, position in 3d space

Setting the Velocity of an Object

struct TS_VelocityInfo

velocity information, describes velocity vector in 3D space

Public Members

float x

velocity along x-axis

float y

velocity along y-axis

float z

velocity along z-axis

void TS_BtSetLinearVelocity(int id, float velocity_x, float velocity_y, float velocity_z)

set the linear velocity of a physics object

Parameters

  • id – id of the object

  • velocity_x – velocity along the x-dimension

  • velocity_y – velocity along the y-dimension

  • velocity_z – velocity along the z-dimension

TS_VelocityInfo TS_BtGetLinearVelocity(int id)

get the linear velocity of a physics object

Parameters

id – id of the object

Returns

TS_VelocityInfo object describing the velocity along each dimension

void TS_BtSetGravity(float gravity_x, float gravity_y, float gravity_z)

set the global gravity

Parameters

  • gravity_x – acceleration along the x-dimension

  • gravity_y – acceleration along the y-dimension

  • gravity_z – acceleration along the z-dimension

Collision Detection

struct TS_CollisionEvent

event used to check whether two objects are colliding

void TS_BtStepSimulation()

advance the physics simulation by one step

TS_CollisionEvent TS_BtGetNextCollision()

query the next collision event

Returns

TS_CollisionEvent, contains two ids of colliding objects