entry-point.rst

Entry Point

All communication between After Effects and an effect plug-in is initiated by After Effects, and it all happens by the host (After Effects) calling a single entry point function.

For all effect plug-ins, the entry point function must have the following signature:

PF_Err main (
  PF_Cmd       cmd,
  PF_InData    *in_data,
  PF_OutData   *out_data,
  PF_ParamDef  *params[],
  PF_LayerDef  *output,
  void         *extra)

The name of the entry point function above is "main", but it can be whatever is specified in intro/pipl-resources.

Before each call to the entry point function, After Effects updates effect-basics/PF_InData and the plug- in's parameter array PF_ParamDef[] (except as noted).

After the plug-in returns from its call, After Effects checks effect-basics/PF_OutData for changes and, when appropriate, uses the PF_LayerDef the effect has rendered.

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Entry Point Function Parameters

Argument	Purpose
cmd <effect-basics/command-selectors>	After Effects sets the effect-basics/command-selectors to tell the plug-in what to do.
in_data <effect-basics/PF_InData>	Information about the application's state and the data the plug-in is being told to act upon. Pointers to numerous interface and image manipulation functions are also provided.
out_data <effect-basics/PF_OutData>	Pass back information to After Effects by setting fields within out_data.
params <effect-basics/parameters>	An array of the plug-in's parameters at the time provided in in_data> current_time. params[0] is the input image (a effect-basics/PF_EffectWorld) to which the effect should be applied. These values are only valid during certain selectors (this is noted in the selector descriptions <effect-basics/calling-sequence>). Parameters are discussed at length here: effect-basics/PF_ParamDef.
output <effect-basics/PF_EffectWorld>	The output image, to be rendered by the effect plug-in and passed back to After Effects. Only valid during certain selectors.
extra <effect-ui-events/PF_EventExtra>	The extra parameter varies with the command sent or (in the case of PF_Cmd_EVENT <effect-basics/command-selectors.messaging>) the event type <effect-ui-events/effect-ui-events>. Used primarily for event management and effect-detals/parameter-supervision.