Caching or Exporting a CrowdFX Simulation

 
 
 

You can cache a CrowdFX simulation in two ways:

Caching the Crowd Point Cloud Simulation

You can create a simulation cache file of a crowd's point cloud in the .icecache file format. You can use this cache file to play back the crowd simulation faster, or to be able to scrub it in the timeline and play it backwards. The crowd particle simulation is cached, including the deformer transformations of each actor instance.

Once you've created a simulation cache file, you can use it on the same simulation point cloud or a different one.

Writing the Cache File

To write a simulation cache file for a crowd's simulation point cloud:

  1. In an explorer, select the Crowd model whose point cloud simulation you want to cache.

  2. Open its CrowdFX Property Editor (for example, press F3), then enter the information in the text boxes as described there.

  3. If you don't enter anything in the Attributes text box, Softimage automatically makes sure that all ICE attributes required for the Actor Copies mesh are included.

    Any attributes you enter here, such as custom attributes for the Actor Copies mesh, are appended to the required attributes. Enter the attributes in a comma-separated list with no spaces between the comma and the next attribute name.

  4. Click the Cache Point Cloud Simulation button to cache the simulation.

    An .icecache file is saved in the path you specified.

Reading the Cache File

Once you've created a simulation cache file, you can use it on a simulation point cloud to play its contents instead of the current simulation. You can use the cache file on the same simulation point cloud or a different one.

If you're loading a cache file onto a different point cloud, its instanced envelope geometry must match that used for the point cloud whose simulation was cached.

To read the cache file:

  1. In an explorer, select the Crowd model on whose simulation point cloud you want to load the cache file.

  2. Open its CrowdFX Property Editor.

  3. Select a cache file in the Simulation Cloud File Path text box. Make sure to remove the [Frame].icecache that is appended to the cache file name.

  4. Enter the Start Frame and End Frame as the first and last frames of the cache file you want to load. These are the frames that are used to create the cache clip in the animation mixer.

  5. Select the Use Cache option to load and apply the specified cache file.

    This creates a hidden point cloud named Point Cloud Cached that contains a cache clip in its Mixer. When Use Cache is selected, this cache clip drives the simulation of the point cloud over the frames that are contained in the cache clip - see Using Cache Files in the Animation Mixer for more information.

    Deselect this option to return to the live simulation on the point cloud.

Exporting the Actor Copies Mesh in an FBX File

You can cache and export the envelope geometry of a Crowd model's Actor Copies polygon mesh in an FBX (.fbx) file. The Actor Copies mesh is the geometry that contains each copy of an actor's geometry that is deformed according to the crowd simulation. If you have several actor proxies in your crowd simulation, each Actor Copies mesh is automatically included in the export.

  1. Make sure that the crowd simulation you want to export is the current one - see Setting the Current Crowd.

  2. Choose the CrowdFX Crowd Export as FBX command from the ICE toolbar.

    This command is similar to a standard Crosswalk export, but has been set up to correctly export the Actor Copies mesh as it is deformed by the crowd simulation. The mesh geometry is cached into nCache files. As well, the ICE Material attributes on the mesh as exported as standard cluster materials.

  3. Set the options in the Export FBX Options Dialog Box dialog box and click OK to create the FBX file.

  4. Import the resulting FBX file into another 3D software, such as Autodesk Maya, or back into Softimage using the standard File Import Import FBX command.

    The Actor Copies meshes are imported as a single object with each actor instance deforming according to the crowd simulation.