|Microsoft DirectX 9.0|
Increases the interface's reference count by 1.
Returns the new reference count. This value is for diagnostic and testing purposes only.
When the interface is created, its reference count is set to 1. Every time an application obtains an interface to the object or calls the IUnknown::AddRef method, the interface's reference count is increased by 1. Use the IUnknown::Release method to decrease the interface's reference count by 1.