Engine COMP


The Engine COMP will run a .tox file (component) in a separate process. It uses TouchEngine to manage these processes and pass data between the loaded component and the main project.

Ins and Outs

The chosen component's top-level Ins and Outs are exposed as Ins and Outs on the Engine COMP. Only TOP, CHOP and DAT Ins and Outs are supported.

Custom Parameters

Any custom parameters on the top-level component are added to the Engine COMP's parameters.

Note that parameters work in one direction only - you cannot set a parameter from within the loaded .tox.

External File Paths

Relative paths on OPs or in scripts inside the loaded component are relative to the .tox file's location. Relative paths as file or folder parameters of the component - those that show up on the Engine COMP - are relative to the main project.

Component Lifetime

Under TouchEngine, components are loaded into an already-running instance. For this reason, an Execute DAT's onStart() and onExit() method will never be executed under TouchEngine. The onCreate() method will be executed when the component is loaded, and is a good place to do any setup you would normally do in onStart().

TouchEngine Versions

TouchEngine is installed as part of TouchDesigner, and the currently running version will be used to load the given .tox. If you wish to use a different version of TouchEngine you can either set the environment variable TOUCHENGINE_APP_PATH to the path to a TouchDesigner installation (an installation directory on Windows, or a TouchDesigner app on macOS) or install TouchDesigner into a folder named TouchEngine alongside the .tox (on macOS rename an application from TouchDesigner to TouchEngine) or create a link named TouchEngine alongside the .tox which points to an installation directory or TouchDesigner app.


Parameters - Engine Page

Tox File file - Specify the .tox file to load with TouchEngine.

Unload unload - Unload the currently loaded component.

Keep Alive keepalive - If the TouchEngine instance quits for any reason, restart it.

Clock clock - - Specify the temporal connection to the TouchEngine instance.

  • Synchronized synced - Time is strictly synchronized between the Engine COMP and the TouchEngine instance.
  • Independent independent - The TouchEngine instance runs according to its own internal clock.

Start on Initialize startoninit - When enabled, playback will start as soon as the component has been loaded.

Initialize initialize - Reload the .tox file, restarting the TouchEngine instance.

Start start - Starts playback of the component in the TouchEngine instance.

Play play - Turn cooking in the TouchEngine instance on or off.

Callbacks DAT callbacks - The Callbacks DAT will execute for events related to the TouchEngine instance.

Parameters - Tune Page

Match Component Rate matchrate - When on, the component will be cooked in TouchEngine at the same rate as the Engine COMP.

Frames per Second fps - The framerate for cooking the component in TouchEngine.

Wait for Render wait - When enabled, if a frame takes a long time to cook in TouchEngine the Engine COMP will wait during cooking rather than dropping the late frame.

This behaviour is affected by the size of the output buffer: eg if Out Buffer Frames is 4, the Engine COMP will wait for the 4th most recent frame to complete.

Render Timeout timeout - When waiting for a frame, TouchEngine will give up waiting after this many milliseconds.

In Buffer Auto inauto - Automatically manage the number of input frames queued.

In Buffer Frames inframes - The number of input frames to queue before passing them to the TouchEngine instance.

To accommodate potential fluctations in time-slice in the TouchEngine instance, CHOP inputs must send a number of frames ahead of time.

Out Buffer Auto outauto - Automatically manage the number of output frames queued.

Out Buffer Frames outframes - The number of output frames to queue after receiving them from the TouchEngine instance.

To accommodate potential fluctations in time-slice in the Engine COMP, CHOP outputs must send a number of frames ahead of time.

Parameters - Extensions Page

The Extensions parameter page sets the component's python extensions. Please see extensions for more information.

Re-Init Extensions reinitextensions - Recompile all extension objects. Normally extension objects are compiled only when they are referenced and their definitions have changed.

Extension Object 1 extension1 - A number of class instances that can be attached to the component.

Extension Name 1 extname1 - Optional name to search by, instead of the instance class name.

Promote Extension 1 promoteextension1 - Controls whether or not the extensions are visible directly at the component level, or must be accessed through the .ext member. Example: n.Somefunction vs n.ext.Somefunction

Parameters - Common Page

The Common parameter page sets the component's node viewer and clone relationships.

Parent Shortcut parentshortcut - Specifies a name you can use anywhere inside the component as the path to that component. See Parent Shortcut.

Global Shortcut opshortcut - Specifies a name you can use anywhere at all as the path to that component. See Global OP Shortcut.

Internal OP Shortcut 1 iopshortcut1 - Specifies a name you can use anywhere inside the component as a path to "Internal OP" below. See Internal Operators.

Internal OP iop1 - The path to the Internal OP inside this component. See Internal Operators.

Node View nodeview - - Determines what is displayed in the node viewer, also known as the Node Viewer. Some options will not be available depending on the Component type (Object Component, Panel Component, Misc.)

  • Default Viewer default - Displays the default viewer for the component type, a 3D Viewer for Object COMPS and a Control Panel Viewer for Panel COMPs.
  • Operator Viewer opviewer - Displays the node viewer from any operator specified in the Operator Viewer parameter below.

Operator Viewer opviewer - Select which operator's node viewer to use when the Node View parameter above is set to Operator Viewer.

Keep in Memory keepmemory - Used only for Panel Components this keeps the panel in memory to it doesn't reload every time it is displayed.

Enable Cloning enablecloning - Control if the OP should be actively cloneing. Turning this off causes this node to stop cloning it's 'Clone Master'.

Enable Cloning Pulse enablecloningpulse - Instantaneously clone the contents.

Clone Master clone - Path to a component used as the Master Clone.

Load on Demand loadondemand - Loads the component into memory only when required. Good to use for components that are not always used in the project.

External .tox externaltox - Path to a .tox file on disk which will source the component's contents upon start of a .toe. This allows for components to contain networks that can be updated independently. If the .tox file can not be found, whatever the .toe file was saved with will be loaded.

Reload .tox on Start reloadtoxonstart - When on (default), the external .tox file will be loaded when the .toe starts and the contents of the COMP will match that of the external .tox. This can be turned off to avoid loading from the referenced external .tox on startup if desired (the contents of the COMP are instead loaded from the .toe file). Useful if you wish to have a COMP reference an external .tox but not always load from it unless you specifically push the Re-Init Network parameter button.

Reload Custom Parameters reloadcustom - When this checkbox is enabled, the values of the component's Custom Parameters are reloaded when the .tox is reloaded. This only affects top-level parameters on the component, all parameters on nodes inside the component are always reloaded with the .tox.

Reload Built-In Parameters reloadbuiltin - When this checkbox is enabled, the values of the component's built-in parameters are reloaded when the .tox is reloaded. This only affects top-level parameters on the component, all parameters on nodes inside the component are always reloaded with the .tox.

Save Backup of External savebackup - When this checkbox is enabled, a backup copy of the component specified by the External .tox parameter is saved in the .toe file. This backup copy will be used if the External .tox can not be found. This may happen if the .tox was renamed, deleted, or the .toe file is running on another computer that is missing component media.

Sub-Component to Load subcompname - When loading from an External .tox file, this option allows you to reach into the .tox and pull out a COMP and make that the top-level COMP, ignoring everything else in the file (except for the contents of that COMP). For example if a .tox file named project1.tox contains project1/geo1, putting geo1 as the Sub-Component to Load, will result in geo1 being loaded in place of the current COMP. If this parameter is blank, it just loads the .tox file normally using the top level COMP in the file.

Re-Init Network reinitnet - This button will re-load from the external .tox file (if present), followed by re-initializing itself from its master, if it's a clone.

Info CHOP Channels

Extra Information for the Engine COMP can be accessed via an Info CHOP.

Specific Engine COMP Info Channels

  • initializing -
  • ready -
  • running -
  • timer_seconds -
  • playing_seconds -
  • running_seconds -
  • reload_count -
  • input_buffer_frames -
  • output_buffer_frames -
  • total_frame_time -
  • frame_did_wait -
  • te_queue_size -
  • te_queue_start -
  • te_queue_end -
  • te_output_time -
  • te_render_ahead_time -
  • engine_fps -
  • engine_frame_msec -
  • engine_cook -
  • engine_dropped_frames -
  • engine_read_ahead_misses -
  • engine_gpu_mem_used -
  • engine_total_gpu_mem -
  • engine_active_ops -
  • engine_deactivated_ops -
  • engine_total_ops -
  • engine_cpu_mem_used -
  • engine_cookstate -
  • engine_cookrealtime -
  • engine_cookrate -
  • engine_timeslice_step -
  • engine_timeslice_msec -

Common COMP Info Channels

  • num_children - Number of children in this component.

Common Operator Info Channels

  • total_cooks - Number of times the operator has cooked since the process started.
  • cook_time - Duration of the last cook in milliseconds.
  • cook_frame - Frame number when this operator was last cooked relative to the component timeline.
  • cook_abs_frame - Frame number when this operator was last cooked relative to the absolute time.
  • cook_start_time - Time in milliseconds at which the operator started cooking in the frame it was cooked.
  • cook_end_time - Time in milliseconds at which the operator finished cooking in the frame it was cooked.
  • cooked_this_frame - 1 if operator was cooked this frame.
  • warnings - Number of warnings in this operator if any.
  • errors - Number of errors in this operator if any.

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