Chapter 14. Actions Passed to an Interact

This chapter describes the actions that can be issued to an interact's main entry point. Interact actions are also generic in character, they could be issued to other plug-in types rather than just Image Effects, however they are not issued directly to an effect's main entry point, they are rather issued to separate entry points which exist on specific 'interact' objects that a plugin may create.

For nearly all the actions the handle passed to to main entry point for an interact will be either NULL, or a value that should be cast to an OfxInteractHandle .

The Describe Action

	#include "ofxCore.h"
	#define kOfxActionDescribe "OfxActionDescribe" 

  • handle handle to the interact descriptor, cast to an OfxInteractHandle
  • inArgs is redundant and is set to NULL,
  • outArgs is redundant and is set to NULL.


The kOfxActionDescribe is the first action passed to an interact. It is where an interact defines how it behaves and the resources it needs to function.

Note that the handle passed in acts as a descriptor for, rather than an instance of the interact.


The plugin has been loaded and the effect described.

Return Values

Default Action

If not trapped, the default action is for the host to carry on as normal