File Cache 2.0

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File Cache 2.0

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The File Cache node can save your Houdini scene data to your hard drive.  File cache 2.0 now allows you to also manage versioning & wedging so that you can cache out different versions of your geometry.
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    Caching out files is one of the most important things you can do to increase the speed of your Houdini workflow.  Any time you want to save out files to be read back into Houdini, you'll usually want to save it out using a "" extension.  It's also important to save out your files to a solid state hard drive if you can afford it because it takes advantage of the fast read/write speeds that a solid state provides.  If you're new to file caching, then check out the Houdini for The New Artist series before moving on to any of the other features of this node.

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General Parameters:

Load From Disk:

--  This allows you to read cache files from your hard drive based on the path which you save out to.  In practice, I recommend that people utilize the "file" node when reading cache files unless you're trying to do something with wedging and/or versioning of cache files.  The reason why I prefer the file node instead of the "Load From Disk" is because this setting can be mis-read from ROP processes (such as the geometry ROP), and because it makes it more obvious that you are reading information from a cache directory.  It sounds like a small thing, but sometimes that little "Load From Disk" checkbox can mistakenly be left unchecked, and it's better to avoid that mistake from happening in the first place.

File Path, Base Name, Base Folder, Time Dependent Cache & Version:

--  There are two options here:  Constructed & Explicit.  Constructed takes the base name, base folder, and version to generate the path to where you'd like to save the cache to.  These paths can be seen by clicking the advanced tab and going to "Path Construction."  Explicit allows you to use variables (such as $HIP or $F4) to automatically generate the file path to where files go.  If you use the explicit method, I usually recommend saying:  $HIP/render/$OS/$OS.$  This translates to... $HIP = Take the file path to my scene, make a folder called "render", $OS = make another folder that's named after the node name, and then call the file the current node name ($OS) followed by the frame number with 4 levels of padding ($F4), and then the file extension which is

--  Keep in mind that if you want to cache out something other than files, you'll need to specify that within the path name.  So, as an example, if you want to save out a .vdb file, you could do so by saying, "$HIP/render/$OS/$OS.$F4.vdb"

--  You'll also notice some icons next to these parameters if you're using the labs version of the file cache.  These icons are macros for creating nodes, adding versions, cleaning up file cache directories, browsing for files, and popping up file explorers to where your cache files exist.  If you click on the geo icon (the one next to the top hat) it will create a "Labs Render Geometry Node" which is responsible for reading in data from the file cache node and giving you more options for display in your scene.  If you click on the tophat icon, it will create a topnet that is found in the /obj context.  In that topnet, you'll find a filecache TOP that links to all the settings you've set in the SOP filecache node.  This is nice because it makes it really convenient when you're trying to do additional tasks in TOPs and you want to bring in the SOP file cache information manually.

--  The Time Dependent Cache is asking you if you need to cache out a single file or multiple files that rely on the frame changing over time.

The Cache Tab:

--  You have the option to "Save to Disk" "Save to Disk in Background" or "Cancel Cook."  Save to disk saves all the files and prevents you from doing anything else in your scene.  (I've found that this option has a hard time wedging things properly)  Or, in most situations, it's better to use Save to Disk in Background.  This option will create a separate task on your computer (imagine booting up a new houdini scene) and rendering that out as a separate task.  This enables you to continue doing stuff in Houdini as things are being rendered "in background."  Finally the "Cancel Cook" is nice because it will interrupt anything that you're rendering to the background.

Enable Wedging (Labs Only):

--  These parameters allow you to "wedge" various settings in sops and separate out those different settings into different file cache directories.  It's easiest to take a look at the video demonstration above to see what this is meant to do.

Wedge Count:

--  The specifies how many wedge values to create.  This determines how many different versions of something you'd like to create

List of Wedges:

--  There is no documentation on this parameter as of writing, but my guess is that you can specify which wedges you'd like to use with this parameter.  As an example, it might allow me to wedge with wedge #1, #2, but then on 3 I don't want to wedge, #4 I do wedge... etc...  In practice, I typically avoid this parameter.

Number of Attributes:

--  When the wedge goes up to affect values in your scene, you can use your own attribute to control the value with each wedge.

Sharpen Features:

--  This is useful for sharpening edges based on the Edge Tolerance.  

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