Joint types and limits for IK and physics.

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Joint types and limits for IK and physics.

Post by dtecta »

I'm currently implementing inverse kinematics on top of Ogre's skeletons for character animation. I'm storing the joint data (types, points, axes, limits) in a separate XML file using the Bone ids from the .skeleton file since a .skeleton file does not keep this data. This data could very well be stored in a .skeleton file as an optional JOINT_DATA chunk and read into a Joint object tied to a Bone or read into a KinematicBone object derived from Bone. I was wondering why this never happened. I've seen discussion on IK popping up over the last 7 years or so but nothing much came out of it. Is this something that is too application specific to be stored in a .skeleton file, or is it simply not being picked up? Certainly the binding of a physics engine to Ogre will benefit from having the joint data as well. I know it is debatable whether or not joint data belongs in the format of a render engine (If you are adding joint data then you would also want to incorporate physical properties such as mass and friction coefficients and before you know it you've lost a lot of genericity), but from a pure pragmatical point of view it makes sense. A lot of animations are generated using IK in e.g. Maya. By exporting the joint data you can generate more natural animations rather than play key-framed animation for every action. So, who's in favour of adding joint data to the skeletal data? Could this be a project for GSoC 2011?


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tuan kuranes
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Re: Joint types and limits for IK and physics.

Post by tuan kuranes »

It could be a gsoc project.
For now I think people use bone/name matching to detect IK bones, and use Node/Animation listener + blending to step in their Own IK code, when they do not replace entirely the animation system with their own in their code with motion graph.
Still, something more formalized for exporter side and engine side, could be would be a welcome addition to Ogre.
(and therefore a more detailed proposal would be required)
Be sure to check existing ogre opensource most animation oriented addon : ... ree+editor

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