Recommended model file formats

OpenGL Development
#1

I’ve reached the point with my hobby ‘engine’ where I’m working on importing third-party models, both static geometry (buildings, terrain, trees, etc) and animated/rigged characters.

I’ve no desire to reinvent the wheel and write hundreds of importers, it would be pointless given that most tools convert to/from the various file formats, but obviously I will need at least something. Problem is I’m unsure what to support: so far I’ve implemented an OBJ loader (for simple static stuff) since it’s pretty trivial and am just putting the finishing touches to an MD5 importer for rigged/skinned animated models.

However I’ve noticed that (for example) Blender does not seem to support exporting of MD5 models (or at least not out-of-the-box?)

So:

  1. What file format(s) would people suggest I support? Ideally it would be one, common, open-source, well-documented format for both static and animated models, but I don’t know if such a thing exists.

  2. I refer to Blender since AFAIK it’s quite widely used and is free - are there more ubiquitous or better (free) tools out there?

  3. If there is no ‘obvious’ answer to the question, does anyone have any suggestions for file formats where at least there are lots of free and easily available models (again both static and rigged) on t’interweb. e.g. 3DS (hideous binary format, poorly documented, but just about does the job?)

Note that I’m not looking for plug-ins, third-party libraries, etc. (although links to open-source code are always welcome) as I want to do this from first principles as part of learning this stuff (yes I am a masochist :wink: ). Also I’m not a modeller, I’m just looking for free animated models that I can nick and use.

I realise this same question has been asked many, many times (obviously been searching in Google on this and other similar sites) but most of the information is at best misleading and usually way out-of-date, so any advice or suggestions are appreciated in advance.

Cheers

  • stride
#2

SMD for animated models. The only format I’ve found that makes sense.

#3

https://developer.valvesoftware.com/wiki/Studiomdl_Data ?

#4

Yep.

#5

SMD is indeed nice and straight-forward, I like the fact that there is ASCII human-readable and binary, compacted formats, and it’s exactly orientated to my requirements.
Also there are off-the-shelf import/export plug-ins for Blender and other tools, perfect.
Thanks for the suggestions.
:slight_smile:

EDIT: Anyone know where I can get hold of some ‘raw’ SMD format animated/skinned models? or will it be easier to try and extract some from a game and convert using the studiomdl tool?

#6

Huh, the Valve site says the SMD format has been superseded by the DMX format. Why stick with SMD?

#7

[quote]Huh, the Valve site says the SMD format has been superseded by the DMX format. Why stick with SMD?
[/quote]
Yes I noticed that when checking out SMD.

IMHO the DMX format is overly complex, poorly documented (have a read through the ‘specification’ on the Valve site) and seems to have little or no tools support other than the few provided by Valve to the community. Also it looks like the only way to get hold of models is to extract them from Counter Strike since it’s the only game to use the format AFAIK, I can’t find a single model available for free on t’internet (though my Google powers are weak). This was all from a relatively cursory investigation however - would love to put straight if I’ve got the wrong perception :wink:

I’ve also cooled on SMD now I’ve started implementing a model loader: Although the file-format is well understood and relatively straight-forward I’m still struggling to find animated, rigged models. There are plenty of static ones, but very few animated. And the ones I’ve found have been exported from tools such as Blender and/or transformed from other formats and the results are frankly garbage - illogical skeleton structures with superfluous bones, vertices that are never referenced, the same (single) vertex weight applied multiple times, duplicate vertices, etc.

I understand skeletal animation and now have loaders for SMD and MD5, but hadn’t expected the problems I’m having simply finding something half-decent to animate! Am I looking for the wrong stuff, in the wrong places?

#8

After reading your post I though to take a look at bone animation myself. And as you I think that dmx is not documented enough.
About animated models which one can use for testing, just search for an animated blender model and export it as smd.

I mean you need to use the blender exporter anyway for your own models, and when the exporter is crap the file format is no good one for your use case.

ps: would you be so kind to share your loader? would get me started quicker.
pss: you can find manny good models here http://www.blendswap.com/

#9

[quote][quote]Huh, the Valve site says the SMD format has been superseded by the DMX format. Why stick with SMD?
[/quote]
IMHO the DMX format is overly complex, poorly documented (have a read through the ‘specification’ on the Valve site) and seems to have little or no tools support other than the few provided by Valve to the community.
[/quote]
Pretty much what I thought too.

Getting models is a bit difficult. The easiest way is to get the models from the Source SDK. Many 3D programs can export the format too if you make your own, at least through plugins.

#10

Cool, that’s the conclusion I was coming to: use Blender to export SMD.

I might spend some time investigating how the exporter works to see if I can improve it and remove or mitigate the problems I mentioned in the previous post (duplicate vertices, unused bones, etc). Or it might just be the models that I’ve tried so far.

I’m at work today and away the weekend but I’ll PM the loader code early next week.

The loaders all use a set of ‘builder’ classes to construct the model scene-graph from the ‘raw’ model data (using core profile functionality only: VAOs, VBOs, UBOs, GLSL shaders, etc). I won’t send them since you’d have to take the entire code-base, but you should be able to refactor or reuse the loader classes themselves to integrate with whatever mesh building / rendering code you plan to use.

Thanks for that, wasn’t aware of that site, and there are a lot of nice freebies on there that I can use, ta :slight_smile: