PSX/HRC

HRC Hierarchy data format

An HRC file is product of the original Playstation Psy-Q 3D development libraries. They describe the bone hierarchy of a 3D model. Most of the time they originally start as a plain text file exported from 3D editing software, or from a 3D file converter. From this they can be "compiled" into binary form more usable for the PSX.

On the PC version of Final Fantasy 7, a text HRC file is used to define the skeletal hierarchy of the field models. The Battle Models use the compiled Format.

But I think that since you read this document, you've got some knowledge 'bout 3D models and skeletons. Let's just start, this format's quite simple! ^_^

HRC file format

Since the HRC files are simple plain-text files, you can open them in notepad or any other text editor. Here are the first four bones of "abjb.hrc" (Yuffie's Hierarchy)

:HEADER_BLOCK 2
:SKELETON sd_yufi_sk
:BONES 24

hip
root
2.9662
1 ABJC 

chest
hip
4.0621967
1 ABJE

head
chest
5.017107
1 ACAA 

joint
head
3.5236073
0

ribon_a
joint
8.52051
1 ACAF
....

The other bones look the same as the ones listed here. These are the parts of the file.

Header

As most files, also the HRC files have got a kind of header. That are the first three lines.

:HEADER_BLOCK 2

This seems to be a simple "ID". As far as I know, this is the first line in all HRCs...

:SKELETON sd_yufi_sk

This tells you the name of the skeleton, in our example "sd_yufi_sk".

:BONES 24

Tells you how much bones are stored in this skeleton.

Bones

Every bone consist of 4 Lines, which look like this. Let's first take a look at the lines of the first bone:

First Line: ("hip")

This is the name of the current bone.

Second Line: ("root")

This is the name of the parent bone. The parent bone must be already listed above in the skeleton file,or it can be "root" (origin).

Third Line: ("2.9662")

That's the Length of the bone.

Fourth Line #1: ("0")

Fourth Line #2: ("1 ABJC")

Fourth Line #3: ("2 ABJC ABJD")

This line consist of 2 or more different values. First, there is a number telling many RSD files are aligned to this model. If it has no RSD File, the number is 0. If the number is 1, there is a string after the number telling you the name of the Resource Data File (RSD). The RSD file tells you which .p Model to use.

There may be even more than 2 RSD Files on 1 Bone, however this has yet be be seen.

Notes

There are no bone angles, just bone lengths. The HRC file only contains hierarchy data. To build a skeleton, animation files are required.