Body Class
A rigid body. Has got a center of mass, position, velocity and a number of shapes that are used for collisions.
Constructor
Body
-
[options]
Parameters:
-
[options]
Object optional-
[mass=0]
Number optionalA number >= 0. If zero, the .motionState will be set to Body.STATIC.
-
[position]
Float32Array | Array optional -
[velocity]
Float32Array | Array optional -
[angle=0]
Number optional -
[angularVelocity=0]
Number optional -
[force]
Float32Array | Array optional -
[angularForce=0]
Number optional
-
Item Index
Methods
Properties
Methods
addShape
-
shape
-
[offset]
-
[angle]
Add a shape to the body. You can pass a local transform when adding a shape, so that the shape gets an offset and angle relative to the body center of mass. Will automatically update the mass properties and bounding radius.
Parameters:
-
shape
Shape -
[offset]
Float32Array | Array optionalLocal body offset of the shape.
-
[angle]
Number optionalLocal body angle.
Example:
var body = new Body(),
shape = new Circle();
// Add the shape to the body, positioned in the center
body.addShape(shape);
// Add another shape to the body, positioned 1 unit length from the body center of mass along the local x-axis.
body.addShape(shape,[1,0]);
// Add another shape to the body, positioned 1 unit length from the body center of mass along the local y-axis, and rotated 90 degrees CCW.
body.addShape(shape,[0,1],Math.PI/2);
adjustCenterOfMass
()
Moves the shape offsets so their center of mass becomes the body center of mass.
applyForce
-
force
-
worldPoint
Apply force to a world point. This could for example be a point on the RigidBody surface. Applying force this way will add to Body.force and Body.angularForce.
Parameters:
-
force
Float32ArrayThe force to add.
-
worldPoint
Float32ArrayA world point to apply the force on.
fromPolygon
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path
-
[options]
Reads a polygon shape path, and assembles convex shapes from that and puts them at proper offset points.
Parameters:
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path
ArrayAn array of 2d vectors, e.g. [[0,0],[0,1],...] that resembles a concave or convex polygon. The shape must be simple and without holes.
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[options]
Object optional-
[optimalDecomp=false]
Boolean optionalSet to true if you need optimal decomposition. Warning: very slow for polygons with more than 10 vertices.
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[skipSimpleCheck=false]
Boolean optionalSet to true if you already know that the path is not intersecting itself.
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[removeCollinearPoints=false]
Boolean | Number optionalSet to a number (angle threshold value) to remove collinear points, or false to keep all points.
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Returns:
True on success, else false.
removeShape
-
shape
Remove a shape
Parameters:
-
shape
Shape
Returns:
True if the shape was found and removed, else false.
setZeroForce
()
Sets the force on the body to zero.
toLocalFrame
-
out
-
worldPoint
Transform a world point to local body frame.
Parameters:
-
out
Float32Array | ArrayThe vector to store the result in
-
worldPoint
Float32Array | ArrayThe input world vector
toWorldFrame
-
out
-
localPoint
Transform a local point to world frame.
Parameters:
-
out
ArrayThe vector to store the result in
-
localPoint
ArrayThe input local vector
updateBoundingRadius
()
Update the bounding radius of the body. Should be done if any of the shapes are changed.
updateMassProperties
()
Updates .inertia, .invMass, .invInertia for this Body. Should be called when changing the structure or mass of the Body.
Example:
body.mass += 1;
body.updateMassProperties();
Properties
angle
Number
The angle of the body
angularForce
Number
The angular force acting on the body
angularVelocity
Number
The angular velocity of the body
boundingRadius
Number
Bounding circle radius
DYNAMIC
Number
static
Dynamic body.
force
Float32Array
The force acting on the body
id
Number
The body identifyer
inertia
Number
The inertia of the body around the Z axis.
invInertia
Number
The inverse inertia of the body.
invMass
Number
The inverse mass of the body.
KINEMATIC
Number
static
Kinematic body.
mass
Number
The mass of the body.
motionState
Number
The type of motion this body has. Should be one of: Body.STATIC (the body does not move), Body.DYNAMIC (body can move and respond to collisions) and Body.KINEMATIC (only moves according to its .velocity).
Example:
// This body will move and interact with other bodies
var dynamicBody = new Body();
dynamicBody.motionState = Body.DYNAMIC;
// This body will not move at all
var staticBody = new Body();
staticBody.motionState = Body.STATIC;
// This body will only move if you change its velocity
var kinematicBody = new Body();
kinematicBody.motionState = Body.KINEMATIC;
position
Float32Array
The position of the body
shapeAngles
Array
The body-local shape angle transforms. This is an array of numbers (angles).
shapeOffsets
Array
The local shape offsets, relative to the body center of mass. This is an array of Float32Array.
shapes
Array
The shapes of the body. The local transform of the shape in .shapes[i] is defined by .shapeOffsets[i] and .shapeAngles[i].
STATIC
Number
static
Static body.
velocity
Float32Array
The velocity of the body
vlambda
Float32Array
Constraint velocity that was added to the body during the last step.
wlambda
Float32Array
Angular constraint velocity that was added to the body during last step.