ContactMaterial Class
Defines what happens when two materials meet, such as what friction coefficient to use. You can also set other things such as restitution, surface velocity and constraint parameters.
Constructor
ContactMaterial

materialA

materialB

[options]
Parameters:

materialA
Material 
materialB
Material 
[options]
Object optional
[friction=0.3]
Number optionalFriction coefficient.

[restitution=0]
Number optionalRestitution coefficient aka "bounciness".

[stiffness]
Number optionalContactEquation stiffness.

[relaxation]
Number optionalContactEquation relaxation.

[frictionStiffness]
Number optionalFrictionEquation stiffness.

[frictionRelaxation]
Number optionalFrictionEquation relaxation.

[surfaceVelocity=0]
Number optionalSurface velocity.

Item Index
Properties
contactSkinSize
Number
Offset to be set on ContactEquations. A positive value will make the bodies penetrate more into each other. Can be useful in scenes where contacts need to be more persistent, for example when stacking. Aka "cure for nervous contacts".
friction
Number
Friction coefficient to use in the contact of these two materials. Friction = 0 will make the involved objects super slippery, and friction = 1 will make it much less slippery. A friction coefficient larger than 1 will allow for very large friction forces, which can be convenient for preventing car tires not slip on the ground.
Default: 0.3
frictionRelaxation
Number
Relaxation of the resulting friction force. The default value should be good for most simulations. Default value is Equation.DEFAULT_RELAXATION.
frictionStiffness
Number
Stiffness of the resulting friction force. For most cases, the value of this property should be a large number. I cannot think of any case where you would want less frictionStiffness. Default value is Equation.DEFAULT_STIFFNESS.
id
Number
The contact material identifier
relaxation
Number
Relaxation of the resulting ContactEquation that this ContactMaterial generate. Default value is Equation.DEFAULT_RELAXATION.
restitution
Number
Restitution, or "bounciness" to use in the contact of these two materials. A restitution of 0 will make no bounce, while restitution=1 will approximately bounce back with the same velocity the object came with.
Default: 0
stiffness
Number
Hardness of the contact. Less stiffness will make the objects penetrate more, and will make the contact act more like a spring than a contact force. Default value is Equation.DEFAULT_STIFFNESS.
surfaceVelocity
Number
Will add surface velocity to this material. If bodyA rests on top if bodyB, and the surface velocity is positive, bodyA will slide to the right.
Default: 0