If the parameter is changed, a reference message will be sent to your plug-in. However, in some scenarios you may want to know when the parameter is begin edited in the UI by the user.

This may occur in the following scenarios:

• If controls need to be added or modified manually by the plug-in to the roll-out
• If a roll-out needs to be manually added or deleted (see one of the Interface::AddRollout() methods in the Interface class).
• If a call-back needs to be called during animation (see Interface::RegisterTimeChangeCallback())

A plug-in can respond to parameter modifications by the user by overriding the following Animatable methods:

• Animatable::BeginEditParams() - Called when the user is changing a parameter.
• Animatable::EndEditParams() - Called when the user is finished editing an objects parameters.