unreal.MovieGraphScriptBase

class unreal.MovieGraphScriptBase(outer: Object | None = None, name: Name | str = 'None')

Bases: Object

This is the base class used for writing scripts that can be executed as part of a Movie Graph Pipeline. After creating a UMovieGraphExecuteScriptNode (named ‘Execute Script’ in the UI) in your Movie Graph Configuration asset, and choosing the type of your script, an instance will be created when the job starts. This instance will persist until the end of the job. The instance will recieve callbacks during the render which contain data that you can manipulate with your script, or data that was generated by the pipeline.

This can be implemented in either C++ or Python. For C++ you can use standard inheritance but for Python you need to write a UClass implemented in Python. This has slightly different syntax than standard Python;

In this example, create a “Python” folder in your Content folder. Then create a file named “MovieGraphPipelineScriptExample.py”, and a file named “init_unreal.py”

In “init_unreal.py” add “import MovieGraphPipelineScriptExample” as the contents. In “MovieGraphPipelineScriptExample.py” use the following:

import unreal unreal.uclass(): class MovieGraphPipelineScriptExample(unreal.MovieGraphScriptBase): unreal.ufunction(override=True): def on_job_start(self, inJobCopy): super().on_job_start(inJobCopy) unreal.log_warning(“OnJobStart”) for shot in inOutputData.graph_data: for layerIdentifier in shot.render_layer_data: unreal.log(“render layer: “ + layerIdentifier.layer_name) for file in shot.render_layer_data[layerIdentifier].file_paths: unreal.log(“file: “ + file) Save and restart Unreal Editor, then create a Movie Graph Configuration with an Execute Script Node, and set it to run MovieGraphPipelineScriptExample. When the job is run, the output console should print “OnJobStart” as a warning. Use “help(unreal.MovieGraphScriptBase)” in the Python Console to see all available overridable functions. See /Engine/Plugins/MovieScene/MovieRenderPipeline/Content/Python for more python examples.

C++ Source:

  • Plugin: MovieRenderPipeline

  • Module: MovieRenderPipelineCore

  • File: MovieGraphExecuteScriptNode.h

is_per_shot_callback_needed() → bool

If you return true here the system will stall at the end of every shot and wait until all files have been written to disk before invoking this callback. This can increase render times but is important if you need to operate on the files on disk as part of the callback.

For C++ implementations override virtual bool IsPerShotCallbackNeeded_Implementation() const override For Python implementations override unreal.ufunction(override=True): def is_per_shot_callback_needed(): return False;

Return type:

bool

on_job_finished(job_copy, output_data) → None

This callback is called at the very end of the Movie Graph Pipeline, right before shutting down. The files specified by the OutputData should have been written to disk by this point. This function will get called both in the case of a successful job, or one canceled by the user. You can use OutputData.bSuccess to determine if the render was successfuly completed.

For C++ implementations override virtual void OnJobFinished_Implementation(UMoviePipelineExecutorJob* InJobCopy, const FMovieGraphPipelineOutputData& OutputData) override For Python implementations override unreal.ufunction(override=True): def on_job_finished(self, inJobCopy, inOutputData): super().on_job_finished(inJobCopy, inOutputData)

Parameters:

  • job_copy (MoviePipelineExecutorJob) – A copy of the job being rendered with this graph config, with its Graph Preset configurations also copied to avoid accidental mutation of assests on disk.

  • output_data (MoviePipelineOutputData) – Information about the files generated during this render. Contains a flag (bSuccess) for checking if the job was successful or not, and contains a list of render layers, and the files written to disk for that render layer. Contains data for all shots rendered up to this point.

on_job_start(job_copy) → None

This callback is called very early on in the Movie Graph Pipeline, before data is read from the job. The provided job is a duplicate of the job defined in the UMoviePipelineQueue, allowing you to make changes to the job without worrying about restoring them at the end of a render. Additionally, the Graph Configuration assets (for both the Primary configuration, and shot overrides) have been duplicated to allow mutation of the graph configuration without worrying about leaking these changes to the assets on disk. Other pointers to external packages (such as the Level Sequence on the job) have not been duplicated though, so be aware that changes to these assets will leak, unless you restore the changes in OnJobFinished. OnJobFinished will be called even if the job is canceled.

For C++ implementations override virtual void OnJobStart_Implementation(UMoviePipelineExecutorJob* InJobCopy) override For Python implementations override unreal.ufunction(override=True): def on_job_start(self, inJobCopy): super().on_job_start(inJobCopy)

Parameters:

job_copy (MoviePipelineExecutorJob) – A copy of the job being rendered with this graph config, with its Graph Preset configurations also copied to avoid accidental mutation of assests on disk.

on_shot_finished(job_copy, shot_copy, output_data) → None

This is similar to OnJobFinished but called after a shot is completed. This is only called if IsPerShotCallbackNeeded() returns true.

For C++ implementations override virtual void OnShotFinished_Implementation(UMoviePipelineExecutorJob* InJobCopy, UMoviePipelineExecutorShot* InShotCopy, const FMovieGraphPipelineOutputData& InOutputData) override For Python implementations override unreal.ufunction(override=True): def on_shot_finished(self, inJobCopy, inShotCopy, inOutputData): super().on_shot_finished(inJobCopy, inShotCopy, inOutputData)

Parameters:
on_shot_start(job_copy, shot_copy) → None

This is similar to OnJobStart but called before a shot is set up. This is only called if IsPerShotCallbackNeeded() returns true.

For C++ implementations override virtual void OnShotStart_Implementation(UMoviePipelineExecutorJob* InJobCopy, UMoviePipelineExecutorShot* InShotCopy) override For Python implementations override unreal.ufunction(override=True): def on_shot_start(self, inJobCopy, inShotCopy): super().on_shot_start(inJobCopy, inShotCopy)

Parameters:

  • job_copy (MoviePipelineExecutorJob) – A copy of the job being rendered with this graph config, with its Graph Preset configurations also copied to avoid accidental mutation of assests on disk.

  • shot_copy (MoviePipelineExecutorShot) – A copy of the shot that is about to be started.