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Quick Summary of Some Skeleton Problems

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Quick Summary of Some Skeleton Problems // Bugs

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Post by Electric Jim // Jul 11, 2008, 7:28am

Electric Jim
Total Posts: 98
There are some bugs related to the bones implementation which I hope get fixed in the upcoming version of trueSpace. Perhaps I could get some confirmation here that these issues have, indeed, been addressed? In case it matters: These issues are manifesting themselves as I try to use bones with a segmented ("robotic") character, having attached each segment of the character to a specific bone with the "Attach object to bone" tool. (So the various segments of the character should move and rotate as I pose the skeleton, but should appear to remain connected to each other, and definitely should not deform. Also, weight painting, etc., should have no impact on the situation.) The first picture shows the figure & skeleton in question, in the default position.


The first issue is the stretching bone problem which manifests itself when a positional lock is active. (To be more precise, it is manifesting itself whenever a positional-plus-rotational lock is active. I haven't tried using pure positional locks with this character.) I first saw this bug reported here (http://forums1.caligari.com/truespace/showthread.php?t=3188&highlight=Bone+Hand) quite some time ago but was not able to find a statement from Caligari anywhere that the bug has been fixed. The second picture shows an example of this problem (along with an example of the next problem).


The second issue may or may not be related to the previous one, though I can say I've only seen it manifest itself when I activate at least one positional-plus-rotational lock. In this situation, I can generally end up posing the skeleton in such a way that at least one of the character's segments appears to become separated from the bone to which it is supposed to remain attached. So far, such segments always appear to be ones that are associated with a branch or with a bone that is connected to a branch. I can somewhat understand the problem with the branch bone itself, since I can't really attach the object to just one part of the branch bone – i.e. to one particular branch of the overall branch structure – as I wish I could. Therefore, the angular orientation of the segment can't really be conveniently defined; instead, it becomes a sort of weighted average of the angular orientations of the different branches of the branch structure. (At least, that's how I think it works, under normal circumstances.) But I can't think of any good reason it should happen with the non-branch bone.


The whole "object becomes separated from its bone" problem can happen even when I don't do any particular posing of the figure. Sometimes, just when I load the file, it comes in with some objects slightly displaced. The third picture gives two views of the figure's pelvis, one with things aligned properly and the other with the objects offset. Sometimes, clicking on some bones or locks will cause the segments to jump into proper alignment with their associated bones, but sometimes, they seem to "try" to do so but end up staying where they are.


These sorts of issues make me extremely leary of spending more time on this project in trueSpace, given that I'm not at all certain I'll be able to achieve the poses I want for the figure, at least not in any reasonable sort of time. Would it be possible for TomG or someone from Caligari to give us a quick "Don't worry, guys; these issues have been fixed in the next version"…?


As always, thanks for your time.

Post by Electric Jim // Jul 27, 2008, 5:42pm

Electric Jim
Total Posts: 98
Update: Though I haven't performed extremely extensive testing yet, some initial playing with my scene in tS7.6 makes it appear that the "bone stretching" and "dislocating" bugs discussed above have been addressed. Barring any discovery that contradicts this, it makes me a VERY happy camper with regard to skeleton usage. :)
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