Application-specific data may be attached to any Animatable in the scene using application data chunks. Application data chunks are represented using AppDataChunk. With the related APIs any 3ds Max object (controller, object, node, modifier, material, etc.) can have custom data attached by other objects. These chunks are saved in the .MAX file and can be accessed through the object they are attached to.

The following methods used to create and retrieve application data are from class Animatable. The data is accessed using three owner identifiers: The SuperClassID and the Class_ID of the owner, and a sub-index.

• Animatable::AddAppDataChunk() - This method is used to add an AppDataChunk to this Animatable. The chunk is identified using the Class_ID, and SuperClassID of the owner, and an ID for sub-chunks.
• Animatable::GetAppDataChunk() - This method is used to retrieve a pointer to an AppDataChunk.
• Animatable::RemoveAppDataChunk() - This method is used to delete an AppDataChunk.

Sample code using these APIs can be found in \maxsdk\samples\utilities\appdata.cpp.

Developers who have 3D Studio / DOS IPAS application data associated with nodes being imported into 3ds Max have APIs available in 3ds Max to help process this imported data. Application data was used by IPAS plug-ins to store special data with nodes. This was used for example by IK and spline patches. These APIs allow a 3ds Max plug-in to request incoming application data from an IPAS plug-in and use it. plug-ins can register a callback that gets called when application data is loaded. The callback can then interpret the data and create a new object that will be used instead of the usual triangle mesh. For more details see the ObjectDataReaderCallback.

Note: Although it is possible to associate application data with the scene or the root node, that data won't be saved in the 3ds Max file since the scene and the root node are not saved.