Undocumented File Format Structures (as of 0.99)

[starknebula]

There exists undocumented data members inside the VOX file format. Proceeding the XYZI data, we can see tags labelled:

1. nTRN
2. nGRP
3. nSHP
4. LAYR

These appear to be non-standard when compared to the other Chunk types as they don't seem to be 4-byte aligned and are may be terminated with 0xFFFFFFFF.

Furthermore the old description for materials MATT appears to have been replaces by a new descriptor MATL which uses strings to identify material properties rather than pure binary.

[starknebula]

If there's anything I can do to help let me know.

[sh-dave]

Please update the docs further, LAYR still isn't documented, also rOBJ seems to be missing.

[scayze]

bump. LAYR and rOBJ is still not documented. would be very appreciated.

[aiekick]

Hello all,

like you, i tried to understand the new file format. i thinck im successfull.

the weird thing about this new format, is the format number (150) is the same in each voxel files i opened .... old files and new :)

i used hexamonkey (http://hexamonkey.com), who is a fabulous binary file analyser,
for tried to write the grammar fo the two vox file.

so i found that the byte offset you seen, is due to the STRING TYPE in each DICT.

and i think the LAYER Chunck is :

i seen that the unknown var is always -1, so i think its a reserved int on 4 bytes, like other reserved items.

so it display that :

here the grammar:

and here the result :

marvelous no ? :)

the grammar file is available on my repor : https://github.com/aiekick/MagicaVoxel_File_Formats
i will post on ,this repo the "voxFileWriter" im curently writing :)

[scayze]

Thank you! This is amazing!

[aiekick]

i not seen the rOBj in my vox files. do you have sample vox file with this rOBJ ? for search the structure

[DanielGilbert]

i not seen the rOBj in my vox files. do you have sample vox file with this rOBJ ? for search the structure

This little 3x3x3 pyramide has the mentioned rOBJ-Tag. It got created with the latest version that supports multiple objects in one file, 0.99.1 under Windows. As it wasn't very complicated to create, it's licensed under WTFPL.

pyramide.zip

[FlayaN]

@DanielGilbert I created a pullrequest with the rOBJ chunk aiekick/MagicaVoxel_File_Writer#1

[aiekick]

i have approved the request. :)

[aiekick]

i added in my repo a basis vox writer with world mode support :) it can be improved i think but for the moment it take the job. my goal was just to export voxel block in new world mode from my Soft "SdfMesher" : https://twitter.com/hashtag/sdfmesher?src=hash

[alexhunsley]

Hi all, found this issue because I'm working on a numpy-vox format lib and I also noticed stuff in the saved vox files not in the file format description.

Just adding a +1 really. @ephtracy, any chance of documenting the current file format doc please?

[alexhunsley]

Or in the very least, updating the model version written to files (apparently it's still at 150), so we can at least know if we're trying to open a file with a model format we don't yet know how to parse.

[ephtracy]

the reason why the version is still 150 is to make the file readable in older versions (the old version only accepts files with version 150).

[ephtracy]

the rendering setting are not open yet because they are changing frequently. But you can still read it since it is just in the DICT format. I will update the format of the Layer chunks though.