SideFX documents the tools that take a .hip file apart, but not the
file itself. What follows is what those tools’ documentation and SideFX’s own forum
establish; details of the individual member files are not formally documented.
A cpio archive
A commercial .hip file is a cpio archive, the old Unix archive format
that stores files one after another, each with a header giving its name and size.
The archive holds a set of small files, mostly hscript command text, plus any
geometry or other data saved inside the scene in Houdini’s own ASCII or binary
forms. Which of cpio’s header variants Houdini writes is not stated in SideFX’s
documentation.
hexpand and hcollapse
| Tool | Usage | What it does |
|---|---|---|
hexpand | hexpand [-p] file.hip | expands the file into a folder of files that ordinary tools can read and edit; -p adds a cpio. prefix to the contents and folder names |
hcollapse | hcollapse [-r] [-p] file.hip | builds the .hip file again from the expanded folder; -r removes the contents file and folder afterwards; -p expects the cpio. prefix |
Both ship with Houdini. SideFX forum posts describe hexpand as a
wrapper around cpio.
Member files
Each node (operator) is stored as several files named after it. Forum posts describe a definition file, an initialisation file and a parameter file, among others; member names reported include:
| Member | Holds (as reported) |
|---|---|
node.def | the node’s definition |
node.init | its initialisation |
node.parm | its parameter values |
node.spare | not described |
node.net | not described |
node_type | not described |
The exact set of members, their order and the syntax inside each are not documented.
.hipnc and .hiplc
Files saved by the non-commercial Apprentice edition (.hipnc) are in a
different, closed form: hexpand refuses them, as SideFX forum answers
confirm. Whether Houdini Indie’s .hiplc can be expanded is not
confirmed.