What is the status of Skeletal Anim

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What is the status of Skeletal Anim

Post  josgraha on Thu Feb 05, 2009 6:27 am

From what I understand MD2 only supports morph animations so I was wondering how far out skeletal animation (.b3d et. al.) was?

If it's not on the radar I was thinking about implementing something maybe using the JAS XML format from Cheetah3D, native FBX support, or MD5 (Doom3 not crypto) depending on what was most readily P&P. Assuming I could parse this model structure into a tree with vertices, deformers, animation curve, and keyframes wondering what aspects of the engine handled the keyframe and morph / mesh deform animations explicitly.

Thanks!

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Re: What is the status of Skeletal Anim

Post  meteors on Thu Feb 05, 2009 10:56 am

As Rom pointed out on another thread, the main issue with skeletal animation is that it's extremely expensive.

I'm definitely interested in it though. You might take a look at how it's implemented in Ogre3D.

By the way, skeletal animation != inverse kinematics.



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Re: What is the status of Skeletal Anim

Post  sio2interactive on Thu Feb 05, 2009 4:22 pm

I am actually researching in my free time on that problem, at the moment Im thinking about creating an "hybrid" type between keyframe and bone animation. In other words, you can animate your model using bones in a modeling software (in occurrence Blender) and then export it by baking only the frame based on the actions set, and in run time doing linear interpolation between theses actions... The processing cost and complexity is alot less than pure bone animation but still gives you most of the positive side of it as well as the one of keyframe... this technique will sacrifice some flexibility over calculation speed. A good balance for low-end hardware I think... more detail on that later...

Cheers,


Last edited by sio2interactive on Fri Feb 06, 2009 5:01 pm; edited 1 time in total
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Re: What is the status of Skeletal Anim

Post  josgraha on Fri Feb 06, 2009 7:18 am

Whoa, I totally didn't think about that and I don't know why that escaped me. There is probably no need from a game standpoint to represent bone vertices and their transform weights on adjacent vertices when all we really care about is performance and the animation itself. I can see why you went for morph animation now because it is cheaper and we are more concerned with the named animation sequence and the vertices location at a given point in time. Thanks for your replies.

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Re: What is the status of Skeletal Anim

Post  meteors on Fri Feb 06, 2009 9:25 am

In my opinion, that compromise is a cheat, and it wouldn't suffice for what I want to do.

Surprised

I'd like to to have true skeletal animation. I'm willing to live without Inverse Kinematics, as this is something few game engines offer.


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Re: What is the status of Skeletal Anim

Post  josgraha on Sat Feb 07, 2009 11:08 pm

Hey this is just an idea but I was looking at something like MotionBuilder to look at creating some really sexy fluid animations (like for a fighting game) but then just exporting the animation sequences as MD2 or whatever SiO2 supports. It's a cheat like texture baking but to have all the various effectors on your rig that you can play with in MotionBuilder would probably make your ipod/iphone explode. Razz What's nice about something like MotionBuilder is that you can really go crazy on the detail so even if there was a really good skeletal interpolator built into your game engine there would still be some stuff you would want to tweak because it would look robotic or not quite lifelike. That's where MB comes in because you can tweak those F-curves like mad and get something really fluid and realistic. Maybe you could look into that.

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Re: What is the status of Skeletal Anim

Post  sio2interactive on Sun Feb 08, 2009 12:30 am

Well I do agree that bone animations are neat and look alot more realistic... but SIO2 have to provide a solution that is acceptable on a large scale... This is why I haven't integrate it in SIO2 yet... of course if you have one animated mesh that's ok... but in the case that you want to do an RPG and you have a whole village to animate that start to be a problem... Bone animation takes a lot calculation and the method provide an infinite amount of intermediary frames... so when you are walking in the village you'll expect to see a dozen of them moving + physic etc... this the device cannot handle it... its too much calculations...

This is why I develop an hybrid approach that let artists use bone animation and when exported only the frames that have been inserted will be executed at run time, you can also create action, interpolate between them, loop them etc... so rendering a few dozen of "villagers" can happen in realtime Wink

I'll try to post a video just to show you guys how it work, and will ask for your comments / suggestions...

Cheers,
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Re: What is the status of Skeletal Anim

Post  exavi on Sun Feb 08, 2009 1:37 am

i think that baking animations like it is right now, may be the most correct approach to animation for the iPhone. Anyways, if there's also the possiblity to make sio2 work with glut, would be cool to have skeletal animation, but would be waaaaaay more cool to have vertex/pixel shaders. ^^

what I mean is that for the iPhone this engine has right now everything anyone needs to make a game.


I'm more a 3d artist(modeler/rigger) than a programmer and I can tell that if I am going to have bone animations without all the fancy bones for secondary animation (ex: a backpack, a cape), automatisms, IK>FK, FK>IK, "muscle" bones and stuff like this (which is impossible) I prefer to bake all my animations into a mesh, because all of these animations can have all the subtle movements that I want baked into them, and not just the amount of bones that the iPhone can handle.

this is nonsense, a GOOD rig is going to have more bones than the amount of them that can be handled in the iphone.
(and by good rig I don't mean character studio's biped)


so I think that MD2 is just perfect for this platform.

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Re: What is the status of Skeletal Anim

Post  sio2interactive on Sun Feb 08, 2009 2:19 am

>> if there's also the possiblity to make sio2 work with glut

Only the I/O have to be adjusted (touch to mouse and screen initialization) as well as some #define cuz Im using some GL ES extensions...

>> would be waaaaaay more cool to have vertex/pixel shaders.

This is not available on the device, the MBX should provide this feature (as well as many others) but they have been taken out... sorry

>> so I think that MD2 is just perfect for this platform.

I kinda agree, but still the size of an MD2 of 4000 frames (basically MD2 default is 198 but you may want more for your game) can be quite huge and have to be loaded in memory... That's why the hybrid approach that I have been develop is perfect for that...

Im uploading videos on Youtube at the moment and have already update the current SVN with tutorial15... I'll post the link of theses vids as soon as the upload is done...

Cheers,

ps: To checkout, from Terminal:

svn checkout http://sio2.googlecode.com/svn/trunk/ sio2-read-only
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Re: What is the status of Skeletal Anim

Post  sio2interactive on Sun Feb 08, 2009 3:39 am

Check it out guys, lemme know what you think:

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Re: What is the status of Skeletal Anim

Post  sio2interactive on Sun Feb 08, 2009 4:13 am

Ok it seems that I mess up something on SVN, I just change for a new client so anyway... if you checkout before this message please checkout again... the new revision is on the way...
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Re: What is the status of Skeletal Anim

Post  exavi on Sun Feb 08, 2009 12:31 pm

hey! I've just checked out the video. seems cool, but when I was talking about the "bake animations" approach I was also thinking about not making the pipeline for graphic artists much blender-specific.

Anyways you are absolutely right, I have never thought about what could happen with a bunch of models with 4K frames each one...


about that pixel/vertex shaders thing that I said, I meant just in case that we were using it in a pc/mac/linux by mixing sio2+glut, Very Happy


...the truth is that would be really cool be able to develop a game with sio2 and be able to use it wherever you want ^^

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Re: What is the status of Skeletal Anim

Post  sio2interactive on Sun Feb 08, 2009 4:25 pm

hey! I've just checked out the video. seems cool, but when I was talking about the "bake animations" approach I was also thinking about not making the pipeline for graphic artists much blender-specific.

>> SIO2 is not blender specific at all, the fileformat is text... and can be exported for any 3D software package...


...the truth is that would be really cool be able to develop a game with sio2 and be able to use it wherever you want

>> I hear'ya, however PC/Mac/Linux is a totally different ball game and would require me to maintain 2 rendering pipeline inside the engine, and that's alot of work...
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Re: What is the status of Skeletal Anim

Post  josgraha on Fri Feb 13, 2009 5:21 pm

exavi wrote:
...the truth is that would be really cool be able to develop a game with sio2 and be able to use it wherever you want ^^

FWIW you might check out Unity 3D for that. I was just looking at Unity (http://www.unity3d.com) and it's _way_ too easy to set up a scene with a bunch of polys on it that drop your FPS to SPF. (pretty bad) But for desktop stuff it's awesome. There's also a web player you can publish your game on the desktop (win/mac) + web (win/mac) which is pretty sweet. Another thing that kinda sucks about Unity for the device is all the cool device specific stuff you get for free with SiO2. For example getting multi-touch, moving logic into applicationDidFinishLaunching and integrating stuff with the CocoaTouch APIs is pretty nice when you start with an XCode project but the end-game in Unity is to generate a XCode project (for iPhone publishing) otherwise it has nice integration with the desktop and web platforms.

Basically the iPhone/iPod kinda sucks for 3D games, I mean I get < 14 frames per second with Bullit + example 6 and if i'm actively moving the camera around and pushing meshes. And I remember hearing in one of the example videos to expect optimal performance (15-30fps) with <=6k polys (not sure if that means rendered and non-occluded or if that meant total including culled / occluded polys). So that makes for a pretty low-rez game which _almost_ kills the purpose of 3D IMHO. Was pretty close to going Diablo2 and pre-rendering everything into a 2D ala Sprite Forge http://www.d-grafix.com/?page=spriteforge but SiO2 is so lightweight and fast it changed my mind there. Cheers!

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