Re: [GD-General] Pelvis transformation during animation

[Nathan M. <Na...@do...>]

It sounds like you are trying to both drive the character's game/logical
position by movement of the root joint and also to use it to skin/deform
the characters. I would suggest that you use different joints for each
purpose. In our engine, we have a joint that we call the delta-trans
that indicates the character's position and rotation deltas for each
frame. That has a child that we call the "Root" joint which is the
basemost deforming joint. At munge time (after export but before the
game gets it) we extract data from the delta-trans and then strip that
joint out of the skeleton. So, in this kind of situation, something like
a backflip might simply translate the delta-trans backwards a bit while
the root and other joints are doing all manner of spins and translation.
I believe that's pretty much how most people do root motion, and a
Google search for "root motion" will probably turn up some good info.
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-Nathan
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-----Original Message-----
From: gam...@li...
[mailto:gam...@li...] On Behalf Of
pontus birgersson
Sent: Wednesday, November 14, 2007 3:32 PM
To: gam...@li...
Subject: [GD-General] Pelvis transformation during animation
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Hi,
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I have encountered an issue that has been a hassle for my current game
project as well as for previous ones and I'd like to hear your take on
it.
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The issue surrounds transforming i.e. rotating and translating the
pelvis joint during animation. We are creating a fighting game where our
artists would like to be able to translate and rotate the entire
character in a non-linear fashion for some animation (say an attack
where the character turns around and moves forward).
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My first approach to this was to let the transformation be part of
pelvis but this causes an issue due to hardware skinning since the world
position and orientation in game logic won't incorporate that particular
transformation seeing as how it is added in the vertex shader.
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Next I tried to extract the transformations into separate rotations and
transformations for each key frame and just add the difference between
key frames to world position and orientation. This solution was flawed
because it also extracts the pelvis translation on the Y axis and adds
that, making the character float upwards. I guess I could keep working
on this solution but it seems as a bad way to go, do you guys have a
better idea or perhaps a standardized way to do this?
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Regards,
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Pontus Birgersson=20
Shortfuse entertainment
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