Overgrowth Engine Animation Style System

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Overgrowth Engine Animation Style System

Post by CrimsonGT »

I was checking out the progress on the Overgrowth engine, and I was really impressed by what they have done with the animation system. I honestly have not worked much with the animation classes in Ogre yet, but this looks like something pretty custom regardless. Somehow they have generic animation skeletons that they can "snap in" to different models, cutting down on the time quite a bit. Anyone know if anything similar to this has been done on here yet, or what would be involved in getting it working?


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Re: Overgrowth Engine Animation Style System

Post by Oogst »

Overgrowth does a lot of custom procedural animation stuff, which parts do you mean exactly?

If skeletons are similar, then you can always apply animations from one skeleton to another. So if all your characters have two arms and two legs, then they can use each other's animations. We used this extensively for the small paint characters in De Blob.

This becomes problematic if leg lengths differ a lot, since the feet won't be on the ground correctly then. In that case the animations would have to be modified through IK (Inverse Kinematics) to place the feet back on the ground. This is a pretty complex process that it not a standard part of Ogre, as far as I know, and requires some serious math, even when done on just two bones (upper leg bone, lower leg bone).

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Re: Overgrowth Engine Animation Style System

Post by Kentamanos »

Based upon the video, I suppose the real "trick" would be generating appropriate weights automatically for the skeleton, right?

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Re: Overgrowth Engine Animation Style System

Post by cyrfer »

I don't think generating the weights automatically should part of the OGRE core as it's quite app-specific. Of course there could be utilities that help with this, but it's pretty specific to the skin and the skeleton defined by the application. The video even states that they put the editor into 'rig mode', and rigging is not the responsibility of OGRE.

Once the weights are assigned, and the skeleton is similar (as Oogst stated), you should be able to share the animation. In OGRE, skeletal animations are stored in separate .skeleton files, and each of those files defines the skeletal structure, so in theory an application could check the bone hierarchy against the target skeleton, and voila- shared animation files. Still, there's nothing more the OGRE core needs to do. This is all app-specific.

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