Category:Physics Engine/Bodies

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A body holds the physical properties (mass, position, rotation, velocity, etc.) of an object. It does not have a shape until you attach one (or more) to it. Its type is TI.cpBody.


Body
body = physics.Body(mass, inertia)


Parameter Type Description
mass in number Mass of the body
inertia in number The inertia of the body
body out physics.Body A new Body with the supplied mass and inertia


Returns a new Body with the given mass and moment of inertia.

Use the provided helper functions to compute the moment of inertia.

Introduced in platform.apiLevel = '2.0'

activate
self = physics.Body:activate()


Parameter Type Description
self in physics.Body The input Body
self out physics.Body The input Body is returned as the output


Activates a sleeping body.

See [http://files.slembcke.net/chipmunk/release/Chipmunk-5.x/Chipmunk-5.3.4-Docs/] for an explanation of this routine.

INFO


Introduced in platform.apiLevel = '2.0'

angle
angle = physics.Body:angle()


Parameter Type Description
self in physics.Body The input Body
angle out number The angle of the Body in radians


Returns the angle in radians of the orientation of the body.

Introduced in platform.apiLevel = '2.0'

angVel
avel = physics.Body:angVel()


Parameter Type Description
self in physics.Body The input Body
avel out number The angular velocity of the Body in radians per unit time


Returns the angular velocity of the body in radians per unit time.

Introduced in platform.apiLevel = '2.0'

applyForce
self = physics.Body:applyForce(forceVect, rOffset)


Parameter Type Description
self in physics.Body The input Body
forceVect in physics.Vect A force vector
rOffset in physics.Vect Vector offset of the force relative to the Body
self out physics.Body The input Body is returned as the output


Apply force vector on self at a relative offset from the center of gravity.

Introducted in platform.apiLevel = '2.0'

applyImpulse
self = physics.Body:applyImpulse(impulseVect, rOffset)


Parameter Type Description
self in physics.Body The input Body
impulseVect in physics.Vect Impulse force on the Body
rOffset in physics.Vect Vector offset of the force relative to the Body
self out physics.Body The input Body is returned as the output


Apply the impulse vector to self at a relative offset from the center of gravity.

Introducted in platform.apiLevel = '2.0'

data
obj = physics.Body:data()


Parameter Type Description
self in physics.Body The input Body
obj out Lua object An object previously set on the Body by the programmer


Returns the contents of the programmer data field of the Body.

Introducted in platform.apiLevel = '2.0'

force
fvec = physics.Body:force()


Parameter Type Description
self in physics.Body The input Body
fvec out physics.Vect The force vector on the Body


Returns the force vector on the body.

Introduced in platform.apiLevel = '2.0'

isRogue
bool = physics.Body:isRogue()


Parameter Type Description
self in physics.Body The input Body
bool out boolean True if the Body is a rogue Body


Returns true if the Body is a rogue Body, never having been added to the simulation Space.

See [http://files.slembcke.net/chipmunk/release/Chipmunk-5.x/Chipmunk-5.3.4-Docs/] for an explanation of rogue bodies.

INFO


Introduced in platform.apiLevel = '2.0'

isSleeping
bool = physics.Body:isSleeping()


Parameter Type Description
self in physics.Body The input Body
bool out boolean True if the Body is sleeping


Returns true if the body is sleeping.

See [http://files.slembcke.net/chipmunk/release/Chipmunk-5.x/Chipmunk-5.3.4-Docs/] for an explanation of sleeping bodies.

INFO


Introduced in platform.apiLevel = '2.0'

local2World
wvec = physics.Body:local2World(lvec)


Parameter Type Description
self in physics.Body The input Body
lvec in physics.Vect A vector relative to the position of the Body
wvec out physics.Vect A vector in world coordinates


Converts lvec from body-relative coordinates to world coordinates. Returns the converted vector.

Introduced in platform.apiLevel = '2.0'

kineticEnergy
ke = physics.Body:kineticEnergy()


Parameter Type Description
self in physics.Body The input Body
ke out number The total kinetic energy of the Body


Returns the kinetic energy of the body.

Introduced in platform.apiLevel = '2.0'

mass
m = physics.Body:mass()


Parameter Type Description
self in physics.Body The input Body
m out number The mass of the Body


Returns the mass of the body.

Introduced in platform.apiLevel = '2.0'

moment
m = physics.Body:moment()


Parameter Type Description
self in physics.Body The input Body
m out number The moment of inertia of the Body


Returns the moment of inertia of the body.

Introduced in platform.apiLevel = '2.0'

pos
p = physics.Body:pos()


Parameter Type Description
self in physics.Body The input Body
p out physics.Vect The position of the Body


Returns the vector position of the body.

Introduced in platform.apiLevel = '2.0'

resetForces
self = physics.Body:resetForces()


Parameter Type Description
self in physics.Body The input Body
self out physics.Body The input Body is returned as the output


Zero both the force and torque accumulated on self.

Introducted in platform.apiLevel = '2.0'

rot
rvec = physics.Body:rot()


Parameter Type Description
self in physics.Body The input Body
rvec out physics.Vect The unit vector orientation of the Body


Returns the vector orientation of the body. This is a unit vector cached from the last calculated angle of the Body.

Introduced in platform.apiLevel = '2.0'

setAngle
self = physics.Body:setAngle(angle)


Parameter Type Description
self in physics.Body The input Body
angle in number The angle of rotation in radians of the Body
self out physics.Body The input Body is returned as the output


Updates the angle of rotation in radians of the body.

Returns the Body.

Introduced in platform.apiLevel = '2.0'

setAngVel
self = physics.Body:setAngVel(vel)


Parameter Type Description
self in physics.Body The input Body
vel in number The angular velocity in radians per unit time of the Body
self out physics.Body The input Body is returned as the output


Updates the angular velocity of the body. The angular velocity is in radians per unit time.

Returns the Body.

Introduced in platform.apiLevel = '2.0'

setData
self = physics.Body:setData(value)


Parameter Type Description
self in physics.Body The input Body
value in object A programmer-supplied Lua object
self out physics.Body The input Body is returned as the output


Sets the programmer data field of the Body. The programmer can store any Lua object in this field. This is a handy place to store a reference to a simulation object.

Returns the Body.

Introduced in platform.apiLevel = '2.0'

setForce
self = physics.Body:setForce(vector)


Parameter Type Description
self in physics.Body The input Body
vector in physics.Vect The vector of force on the Body
self out physics.Body The input Body is returned as the output


Updates the force vector on the body.

Returns the Body.

Introduced in platform.apiLevel = '2.0'

setMass
self = physics.Body:setMass(mass)


Parameter Type Description
self in physics.Body The input Body
mass in number The mass of the Body
self out physics.Body The input Body is returned as the output


Updates the mass of the body.

Returns the Body.

Introduced in platform.apiLevel = '2.0'

setMoment
self = physics.Body:setMoment(moment)


Parameter Type Description
self in physics.Body The input Body
moment in number The moment of inertia of the Body
self out physics.Body The input Body is returned as the output


Updates the moment of inertia of the body.

Use the provided helper functions to compute the moment of inertia.

Returns the Body.

Introduced in platform.apiLevel = '2.0'

setPos
self = physics.Body:setPos(vector)


Parameter Type Description
self in physics.Body The input Body
vector in physics.Vect The position of the Body
self out physics.Body The input Body is returned as the output


Updates the position of the body.

Returns the Body.

Introduced in platform.apiLevel = '2.0'

setPositionFunc
self = physics.Body:setPositionFunc(func)


Parameter Type Description
self in physics.Body The input Body
func in function(body, dt) A callback function that updates the position of the Body on each time step
self out physics.Body The input Body is returned as the output


Sets the position function of the body. The position function must be a function that accepts a Body and a time step value and at some point calls body:updatePosition to update the position of the body.

Returns the Body. 


-- TODO This is a lame example

function samplePositionFunc(body, dt)
-- What goes here?
body:updatePosition(dt)
end

body:setPositionFunc(samplePositionFunc)


TIP: Example


Introduced in platform.apiLevel = '2.0'

setTorque
self = physics.Body:setTorque(torque)


Parameter Type Description
self in physics.Body The input Body
torque in number The torque of the Body
self out physics.Body The input Body is returned as the output


Updates the torque on the body. Torque is a numeric magnitude.

Returns the Body.

Introduced in platform.apiLevel = '2.0'

setVel
self = physics.Body:setVel(vector)


Parameter Type Description
self in physics.Body The input Body
vector in physics.Vect The velocity vector of the Body
self out physics.Body The input Body is returned as the output


Updates the velocity of the body.

Returns the Body.

Introduced in platform.apiLevel = '2.0'

setVelocityFunc
self = physics.Body:setVelocityFunc(func)


Parameter Type Description
self in physics.Body The input Body
func in function(body, grav, damping, dt) A callback function that updates the velocity of the Body on each time step
self out physics.Body The input Body is returned as the output


Sets the velocity function of the body. The velocity function must be a function that accepts a Body, a gravity vector, a numeric damping factor, and a time step value. The function should call body:updateVelocity to adjust the velocity of the body.

Returns the Body. 


function sampleVelocityFunc(body, gravity, damping, dt)
local pos = body:pos()
local sqdist = pos:lengthsq()
local g = pos:mult(-GravityStrength / (sqdist * math.sqrt(sqdist)))
body:updateVelocity(g, damping, dt)
end

body:setVelocityFunc(sampleVelocityFunc)


TIP: Example


Introduced in platform.apiLevel = '2.0'

setVLimit
self = physics.Body:setVLimit(limit)


Parameter Type Description
self in physics.Body The input Body
limit in number The maximum speed of the Body
self out physics.Body The input Body is returned as the output


Sets the limit for the maximum speed of the body.

Returns the Body.

Introduced in platform.apiLevel = '2.0'

setWLimit
self = physics.Body:setWLimit(limit)


Parameter Type Description
self in physics.Body The input Body
limit in number The maximum angular velocity of the Body
self out physics.Body The input Body is returned as the output


Updates the limit of the angular velocity of the body. Angular velocity is in radians per unit time.

Returns the Body.

Introduced in platform.apiLevel = '2.0'

sleep
self = physics.Body:sleep()


Parameter Type Description
self in physics.Body The input Body
self out physics.Body The input Body is returned as the output


Puts the body to sleep.

See [http://files.slembcke.net/chipmunk/release/Chipmunk-5.x/Chipmunk-5.3.4-Docs/] for an explanation of sleeping bodies.

INFO


The body must be added to a Space before it can be put to sleep.

Calling this function within a query or callback is not allowed.

NOTE: NOTES


Introduced in platform.apiLevel = '2.0'

sleepWithGroup
self = physics.Body:sleepWithGroup( [group] )


Parameter Type Description
self in physics.Body The input Body
group in physics.Body A sleeping body. If this parameter is not supplied, a new group is created
self out physics.Body The input Body is returned as the output


Puts the Body to sleep and adds it to a group of other sleeping bodies.

See [http://files.slembcke.net/chipmunk/release/Chipmunk-5.x/Chipmunk-5.3.4-Docs/] for an explanation of this routine.

INFO


The body must be added to a Space before it can be put to sleep.

Calling this function within a query or callback is not allowed.

NOTE: NOTE


This routine will raise an exception if group is not sleeping.

Introduced in platform.apiLevel = '2.0'

torque
t = physics.Body:torque()


Parameter Type Description
self in physics.Body The input Body
torque out number The torque on the Body


Returns the torque on the body.

Introduced in platform.apiLevel = '2.0'

updatePosition
physics.Body:updatePosition(dt)


Parameter Type Description
self in physics.Body The input Body
dt in number The time interval in seconds


Updates the position of the body using Euler integration.

See [http://files.slembcke.net/chipmunk/release/Chipmunk-5.x/Chipmunk-5.3.4-Docs/] for an explanation of this routine.

INFO


Introduced in platform.apiLevel = '2.0'

updateVelocity
physics.Body:updateVelocity(grav, damp, dt)


Parameter Type Description
self in physics.Body The input Body
grav in physics.Vect The force of gravity
damp in physics.Vect The damping factor
dt in physics.Vect The time interval in seconds


Updates the velocity of the body using Euler integration.

See [http://files.slembcke.net/chipmunk/release/Chipmunk-5.x/Chipmunk-5.3.4-Docs/] for an explanation of this routine.

INFO


Introduced in platform.apiLevel = '2.0'

vel
vvel = physics.Body:vel()


Parameter Type Description
self in physics.Body The input Body
vvel out physics.Vect The velocity of the Body


Returns the vector velocity of the body.

Introduced in platform.apiLevel = '2.0'

vLimit
vmax = physics.Body:vLimit()


Parameter Type Description
self in physics.Body The input Body
vmax out number The maximum speed of the Body


Returns the speed limit of the body.

Introduced in platform.apiLevel = '2.0'

wLimit
wmax = physics.Body:wLimit()


Parameter Type Description
self in physics.Body The input Body
wmax out number The maximum angular velocity of the Body in radians per unit time


Returns the angular velocity limit of the body. The angular velocity is in radians per unit time.

Introduced in platform.apiLevel = '2.0'

world2Local
lvec = physics.Body:world2Local(wvec)


Parameter Type Description
self in physics.Body The input Body
wvec in physics.Vect A vector in world coordinates
lvec out physics.Vect A vector relative to the position of the Body


Converts wvec from world coordinates to body-relative coordinates. Returns the converted vector.

Introduced in platform.apiLevel = '2.0'

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