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Jasper91

OpenGL Best 3d format for models

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Hi all, i'm new here so hello all... I'm using C++/OpenGL for a while now but i couldn't find an answer for my question on google so thats why i came here :D. My question: Which 3d-format is the best for using in OpenGL and how can i use them? I'm able to use the following formats: 3ds, ac, fbx, dae, off, x, lwo, mot, md2, flt, iv, map, raw, fix, x3d and obj. Thanks! Jasper

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I've heard people enjoy working with md2, but that's from a small group of programmers, but i would wait for more experienced people to reply besides my own.

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It really depends on your needs. If you just need to load mesh data, stick with simple ones. OBJ is human readable and easy to load. You have to write a parse to pull out what you need, so the readability is helpful for your first format.

Here's a page about OBJ.

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hey

Yep, it all depends on what you are looking todo.

Of the formats your have mentioned, the only ones I know a little about are 3ds, md2, map, and obj.

Basically, if you are starting out and wish to code your own model/mesh loader, I would highly recommend the WaveFront *.OBJ format, as it has a very simple ASCII format. It supports vertex position/normal/texcoord, and quad/triangle index data. I think it also supports some form of material data.

If you are looking for a nice allround format that supports skeletal animation, then I highly recommend the DirectX *.X format. Hmm, although you didn't mention this format, I think it's quite well supported by various 3d software packages or whatever. There is a text/ascii, and binary version of this format, but I think the text/ascii is most supported, although it might be harder to process.

Otherwise you could always just design your own format, and make an exporter for it.

BTW, if you want to find docs on any of these formats, then let me know and I'll dig something up for ya.
---

Well thought I'd tell you my probs with the formats you mentioned that I know of.

3ds: Although I think it supports some form of animation, I don't think it properly supports either mesh or skeletal animation.

md2: Vertex point/normal data is compressed into 1 BYTE per coordinate, and texcoord data is represented with 2 BYTES per coordinate. Hmm, incase you don't know, usually vertex point/normal/texcoord data is represented with 4 BYTES per coordinate, this means there is much less precision.

map: Assuming this is the Quake3, or simular HalfLife format, then this format is only useful for maps. The problem is that these are quite hard to load, as geometry is represented by these things called brushes, and to construct your mesh from these brushes you must perform some quite tricky CSG (Constructive Solid Geometry) operations.
---

edit
Although I know very little about the Collada *.DAE format, what I think I do know is that it's designed to be like a standard middle ground format, and thus should support anything common to many 3d software packages. I'm not sure how well this format is supported, but it certainly would be worth looking into.

Hmm, my only concern is that I think this format is XML based, so I think it may not be so strait forward to read/load data and such from it. I think you would need to implement an XML parser or whatever, but I'm quite sure there would be some libs for such things.

cyas

[Edited by - yosh64 on July 14, 2007 1:55:38 AM]

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My two cents: don't even think at using a shared assets format for your technology. It's not a good idea, really.

My two cents about the formats I know...
Quote:
Original post by Jasper91
3ds, fbx
3DStudio and Maya respectively. You don't want to support this natively, although a filter to your own (more restrictive) format is highly desiderable. Even in this case however, only partial support will likely suffice. Camera entities for example will unlikely be useful unless you intend to use them as portals.
Quote:
Original post by Jasper91
obj
This is a bit outdated for today' standards. Theorically, you don't want to support it but it happens so many programs support it you pratically must have a filter. It must also work fast and work out-of-core. It's tremendously easy for a OBJ file to weight far over 100MB. Although this isn't really a problem on today's PC by itself, some care must be taken to avoid blow up your heap (the one malloc and new takes memory from), especially for DCC software which may be running other tasks as well.
Quote:
Original post by Jasper91
dae
As yosh64 said, this is Collada. Supporting it thoroughtly is above human capabilities. ;-) The format is terribly complex and feature rich. Sticking to a choosen subset will likely cut it most of the time. Don't even think at having NATIVE support for it (unless you're writing DCC software). Collada is designed to be put in filters. The format itself as all XML based things is terribly redundant, even worse than others such as OBJ or whatever.
Quote:
Original post by Jasper91
md2
I see very little reason to support this one. I've had a quick glance at it a few time ago and I remember it wasn't exactly nice, it's still far better than having to parse ASCII.
Personally I don't like it much, but I recognize it can be useful.
Quote:
Original post by yosh64
map: Assuming this is the Quake3, or simular HalfLife format, then this format is only useful for maps. The problem is that these are quite hard to load, as geometry is represented by these things called brushes, and to construct your mesh from these brushes you must perform some quite tricky CSG (Constructive Solid Geometry) operations.

Not exactly.
Most editors will give you pre-mangled .map files.
Then, each brush will be represented by a bounduary-representation polygons (think at it as some kind of "local" BSP).

Mangling the various polygons, even when "predigested" isn't exactly easy. GtkRadiant does have an implementation which takes a bit of memory, works on doubles and produces pleasing results - it's possible to break it in some extreme cases but this happens VERY rarely even on assets designed for the purpose.

Again, don't even think at supporting this natively (quakeX doesn't do for a reason).
There are very good assets around using this format and this means that a filter is desiderable to tap the available resource.

I would suggest to roll your own format and then write filters to "convert" the assets.
Anyway, if you can work with a "well known" format then I suggest to choose a binary based one. The structure of binary files ensure that most errors are trivially detected and rejected. With ASCII, it's often far from easy.

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Another format worth mentioning is Valve's SMD format. It's been around for almost ten years, it's a text-based format, and it supports skinned meshes. AFAIK there are exporters for every major 3D package for it.

The downside, of course, is its legality is ambiguous given it's a private format used by a commercial game developer. But then I've seen a couple of projects that use Half-Life .maps which is just as ambiguous.

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Hopefully this post isn't dead but I just want to say, if you invest in learning python, you can create your own export model format which will be easy, as you made it so you'll know all the specs.

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Quote:
Original post by ViperG
I've heard people enjoy working with md2, but that's from a small group of programmers, but i would wait for more experienced people to reply besides my own.

I'd prefer md3 over md2...

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Hi,

the format selection depends on your needs. Stick to some easy format like md2 if you're just learning or in need of a quick and easy way to get some modeldata imported.

If you're disposed to invest some time you should take a look at collada. It seems to be quite complex, but it contains all you need. Using a simple format starts to hurt when you're trying to get more complex information from your model (material, shader, bones, animations). Typically you start to change your format (what doesn't meet all your requirements) and finally you are writing your own exporter (which is limited to one modelling program). If you invest the time in collada, you will benefit from it in the long term. Here are the most important advantages of collada:

1. It is free, human readable(XML) and a standard ! (Think of OpenGL/DirectX)
2. It contains all you need (including bone infomation, animation, materials ...)
3. There are free support libraries: domCollada (open-source, api to access the xml file) and FCollada (high level access).
4. almost every important modeling tool supports collada: maya, max, blender ...

My suggestion:
Take blender (free modelling tool), make a textures cube, export it to collada and start writing a simple import module using domCollada or FCollada. After extensive testing take a md2 model and import/export it with blender to collada. Extend your import program when needed.

--
Ashaman

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