= Import, export, and cache geometry to/from disk =

== Overview ==

Houdini lets you store geometry on disk in `.geo` or `.bgeo` format files. The file extension controls which format Houdini saves. `.geo` is a simple ASCII format, `.bgeo` is a much more compact binary format. Unless you want to use external scripts to process the geometry files for some reason, use `.bgeo` as the extension for geometry files.

(The `.geo` file format is documented [here|/io/formats/geo].)

TIP:
    The [File surface node|Node:sop/file] can also load geometry data directly from saved simulation state (`.sim`) files. See the help for the [File node|Node:sop/file] for more information.

== Export ==

tasks>>
    Save the geometry in a node as a one-shot action:
        In the [network editor|/ref/panes/network], right-click a surface node and choose __Save geometry__.
        
    Set up a File node to write geometry each time it cooks:
        # In the [network editor|/ref/panes/network], add a [File node|Node:sop/file] and connect the geometry network to its input.
        
        # In the node's parameters, set __File mode__ to __Write__.
        
        # Set the __Geometry file__ to the file on disk to write to.
        
            If your geometry is animated, you can [include $F in the filename|/rendering/expressions] to write out separate files for each frame.
        
        Also see the section on caching below.
        
    Set up writing geometry as part of a render dependency network:
        The [Geometry render node|Node:out/geometry] "renders" the scene as a geometry file.
        
        # Choose __Render > Create render node > Other output nodes > Geometry__.

        # In the Geometry node's parameters, set the __SOP Path__ to the object or geometry node whose geometry you want to save.
    
        # Set the __Output name__ to the name of the file to save the geometry into (should end in `.geo` or `.bgeo`).
    
            If your geometry is animated, you can [include $F in the filename|/rendering/expressions]  to write out separate files for each frame.
    
        # Click the __Render__ button at the top of the parameter editor to
          create the geometry files.
        
== Import ==

tasks>>
    Import geometry into a new object:
        Choose __File > Import > Geometry__.
        
        This creates a new object containing a [File node|Node:sop/file] to load the geometry.
        
    Import geometry into a geometry network:
        # In the [network editor|/ref/panes/network], add a [File node|Node:sop/file].
        
        # In the node's parameters, set the __Geometry file__ to the file on disk to read.
        
            If you saved out animated geometry is animated, you can [include $F in the filename|/rendering/expressions] to read in separate files for each frame.
            
        TIP:
            Press ` (backquote, above the ((Tab)) key on US keyboards) in the network editor to open a file chooser which lets you choose a geometry file and automatically creates a [File node|Node:sop/file] in the network.

== Caching geometry ==

The [File surface node|Node:sop/file] lets you write out geometry the first time the node cooks, and then use the saved geometry from then on, giving a simple form of on-disk caching. To refresh the cache, delete the files on disk.

# In the [network editor|/ref/panes/network], add a [File node|Node:sop/file] and connect the geometry network to its input.

# In the node's parameters, set __File mode__ to __Automatic__.

# Set the __Geometry file__ to the file on disk to write to.

    If your geometry is animated, you can [include $F in the filename|/rendering/expressions] to write out separate files for each frame.

# You can add nodes to the File node's output to further process the cached geometry.

== See also ==

- [Surface nodes|/nodes/sop]