This topic pertains only to application development in Visual Basic. See DirectInput C/C++ Tutorials.

Let's suppose that in your application you wish to simulate the pull of a stationary object (say a magnet) on a movable object (say an iron ball) controlled by the joystick. At the beginning of the simulation, the iron ball is due south of the magnet and experiencing one-half the maximum possible pull.

You will simulate the pull of the magnet by a constant force. First you set up the DIEFFECT type that describes the force:

Dim EffectInfo as DIEFFECT
With EffectInfo
  .constantForce.lMagnitude = 5000
  .lDuration = -1       ' Infinite
  .x = 18000
  .lGain = 10000        ' Play at full magnitude
  .lTriggerButton = -1  ' No trigger button
End With

All the other members of DIEFFECT are either not relevant to a constant force or are valid as 0.

Now create the effect:

Dim di_effect As DirectInputEffect
Set di_effect = didev.CreateEffect("GUID_ConstantForce", EffectInfo)

If the device is in an acquired state at this time, the effect is automatically downloaded. If not, the effect will be downloaded when it is started.

di_effect.Start(1, 0)

Only one iteration of the effect is needed, since it has infinite duration, and no flags are required in this case.

Next: Step 4: Modify an Effect