API Docs for: 0.7.1
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ContactEquation Class

Non-penetration constraint equation. Tries to make the contactPointA and contactPointB vectors coincide, while keeping the applied force repulsive.

Constructor

ContactEquation

(
  • bodyA
  • bodyB
)

Parameters:

Methods

addToWlambda

(
  • deltalambda
)

Add constraint velocity to the bodies.

Parameters:

  • deltalambda Number

computeB

() Number

Computes the RHS of the SPOOK equation

Returns:

Number:

computeGiMf

() Number

Computes G*inv(M)*f, where M is the mass matrix with diagonal blocks for each body, and f are the forces on the bodies.

Returns:

Number:

computeGiMGt

() Number

Computes G*inv(M)*G'

Returns:

Number:

computeGq

() Number

Computes G*q, where q are the generalized body coordinates

Returns:

Number:

computeGW

() Number

Computes G*W, where W are the body velocities

Returns:

Number:

computeGWlambda

() Number

Computes G*Wlambda, where W are the body velocities

Returns:

Number:

computeInvC

(
  • eps
)
Number

Compute the denominator part of the SPOOK equation: C = G*inv(M)*G' + eps

Parameters:

  • eps Number

Returns:

Number:

gmult

() Number

Multiply a jacobian entry with corresponding positions or velocities

Returns:

Number:

update

()

Compute SPOOK parameters .a, .b and .epsilon according to the current parameters. See equations 9, 10 and 11 in the SPOOK notes.

Properties

bodyA

Body

First body participating in the constraint

bodyB

Body

Second body participating in the constraint

contactPointA

Array

Vector from body i center of mass to the contact point.

contactPointB

Array

World-oriented vector from body A center of mass to the contact point.

enabled

Boolean

Whether this equation is enabled or not. If true, it will be added to the solver.

firstImpact

Boolean

This property is set to true if this is the first impact between the bodies (not persistant contact).

G

Array

The Jacobian entry of this equation. 6 numbers, 3 per body (x,y,angle).

maxForce

Number

Max force to apply when solving.

minForce

Number

Minimum force to apply when solving.

multiplier

Number

The resulting constraint multiplier from the last solve. This is mostly equivalent to the force produced by the constraint.

needsUpdate

Boolean

Indicates if stiffness or relaxation was changed.

normalA

Array

The normal vector, pointing out of body i

relativeVelocity

Number

Relative velocity.

relaxation

Number

The number of time steps needed to stabilize the constraint equation. Typically between 3 and 5 time steps.

restitution

Number

The restitution to use (0=no bounciness, 1=max bounciness).

shapeA

Shape

The shape in body i that triggered this contact.

shapeB

Shape

The shape in body j that triggered this contact.

stiffness

Number

The stiffness of this equation. Typically chosen to a large number (~1e7), but can be chosen somewhat freely to get a stable simulation.