At its most basic, skin and bones animation defines a "skeleton" in terms of a frame underneath the surface mesh of a model, able to bend or twist at joints within given ranges with those bends and rotations then affecting the skin appropriately. In terms of your model I think you would need your figure to be a single geometry and for the animation to affect the points within that, but I'm not certain.
At a more complex level a body can be modelled as a skeleton with a layer of musculature that contracts and extends as it is used followed by a layer of connective tissue then the skin of the model. I don't know if this is being used in real-time applications yet- quite possibly it is not. I don't know a whole lot about this, really, I was looking into it the other day - it is often associated with Inverse Kinematics and using that in searches tends to find more accurate results. Here is a possibly useful starting point: http://www.cs.umu.se/~c97psa/exjobb/pager2.cgi?action=show&page=references -ben -----Original Message----- From: Discussion list for Java 3D API [mailto:[EMAIL PROTECTED] Behalf Of Silvère Martin-Michiellot Sent: 11 November 2003 17:59 To: [EMAIL PROTECTED] Subject: Re: [JAVA3D] skin and bones animation At 14:10 10/11/2003 +0000, you wrote: >Hi, >I have a 3D model of a human figure - each limb has its geometry defined >under a series of TransformGroups enabling me to control how the >character moves. This is ok but it's difficult to precisely state where >the joint is so as to minimise gaps that appear if a limb is bent to an >extreme and so on. I am sure this is a common problem. > >My question is, though, can someone please explain what graphic artists >mean when they talk about "skin and bones animations" or "skeleton and >skin animation"? Is this where as a figure moves, the skin (clothes or >whatever) "stretch" so that the above gap problem does not occur? As far as I know there are specific algorithms to "merge" to shapes together so that when you twist the upper torso, the lower part is also affected. I don't think many games do use that as it is a complexity overhead. I don't neither think morphing is used also I have developed this in my hanim package. Dave Yazel for magicosm can probably say more about animation in Java in a realistic situation. This is a topic on which I ask myself many questions and I'd be happy to receive information on the topic (code/articles) should anyone have some. >How can such animated figures be included in Java3D? Is it a case of >loading the key frames and morphing between them? How effective is that >? What is the performance [overhead] like? > >I guess the problem then becomes that you are limited to whatever >animations have been developed by the graphic artist. Or is there a way >of controlling individual limb movement from the files they generate? > >What happens in professional games? How are they developed? > >Please forgive me for asking a question that to you all may seem common >knowledge - all the articles that I've found on this are written from a >graphics perspective and do not talk about how such animations are dealt >with in Java3D, or any other development platform for that matter. > >Many thanks, >-Paul > >=========================================================================== >To unsubscribe, send email to [EMAIL PROTECTED] and include in the body >of the message "signoff JAVA3D-INTEREST". For general help, send email to >[EMAIL PROTECTED] and include in the body of the message "help". __________________________________________________________________________________________ Silvere Martin-Michiellot builds the Internet future on www.digitalbiosphere.com __________________________________________________________________________________________ =========================================================================== To unsubscribe, send email to [EMAIL PROTECTED] and include in the body of the message "signoff JAVA3D-INTEREST". For general help, send email to [EMAIL PROTECTED] and include in the body of the message "help". =========================================================================== To unsubscribe, send email to [EMAIL PROTECTED] and include in the body of the message "signoff JAVA3D-INTEREST". For general help, send email to [EMAIL PROTECTED] and include in the body of the message "help".
