CodeRecipe(…)

What is a spring ?

A spring is a constraint similar to a joint , the only difference being that , in a spring constraint the constraint between 2 rigidbodies can be interchanged dynamically.

As in , during program execution one can change the constraint between rbA<->rbB to say rbA<->rbC .

Apart from this and the change in method to create a spring , no significant difference was found. Please refer Angular Joint for the diagram.

Syntax and usage:
createSpring( ConstraintDesc desc, symbol forceExertionMode , float restLength)

ConstraintDesc
Required. Reference to the constraint descriptor object.

forceexertionmode
Takes the following symbol values.

#kDuringCompression - Restoring force will be applied only when the actual length is less than the rest length between objectA and objectB.

#kDuringExpansion - Restoring force will be applied only when the actual length is more than the rest length between objectA and objectB.

#kBoth - Restoring force will be applied in both the above cases.

restlength
Required. Float value that specifies the rest length of the spring.

Example code :

-- Spring constraint Descriptor between two rigid bodies' b1 and b2.
pocA = vector(6.0,0.0,0.0)
pocB = vector(8.0,0.0,0.0)
SpringDesc = ConstraintDesc("SpringDesc",b1,b2,pocA,pocB,500,1)
--Create a spring which has expansion and compression with a rest length of 5.
member("PhysicsWorld").createSpring(SpringDesc,#kboth,5.0)