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Thread: animation ideas

  1. #11
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    Let me make it clear.

    I NEED BAKED MATRICES, ONE PER FRAME AND I NEED BAKED PARAMETERS ONE PER FRAME.

    Anything else means that my artists can not use every feature of their animation package. How are can expressions be turned into keyframes? How are can joint constraints be turned into keyframes? The keyframe might go from 0 to 1 to 0 but the constraint keeps it between 0.2 and 0.8

    Maybe my object is animated by riding it on a space warp. Maybe my object is following a NULL/Locator so that there is are no actual keyframes on the visible object but their are on the NULL. Maybe my light's brightness is an expression based on the angle of the camera to the horizon. Maybe my artists are actually manipulating the matrix in strange ways to achieve cartoon like effects doing more than trans/rot/scale/skew. I could come up with thousands of situations where keyframes will not handle the animation my artists make.

    All I'm asking is please don't make collada unusable by those of us that would rather let our artists do their best work.

  2. #12
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    Quote Originally Posted by greggman
    I NEED BAKED MATRICES, ONE PER FRAME AND I NEED BAKED PARAMETERS ONE PER FRAME.
    Can you be clearer about what you mean by 'frame'? Is that a 60Hz frame? 50Hz? 24fps?
    Andrew Ostler
    Senior Principal Programmer
    SCEE

  3. #13
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    How about a sample rate setting for the exporter

    I generally do it by sampling at 60hz and then curve fitting the results. Similar to how Granny does it.

  4. #14
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    On baked data:

    I'd prefer separate scaling, rotation and translation inputs from which animated matrices would be built. That way if any of these components is not present in the data it doesn't have to be present in the Collada file either: with consequent reduction in file size.

    On keyframing, I'd like the user to have two options:

    1. Output data for every frame.

    2. Keyframed. The exporter would be responsible for determining where keyframes are required. By default only those frames that are keyframed by the artist would be output (along with an indication of how to interpolate). If there are controllers present that invalidate this approach then the exporter would add keyframes where necessary.

  5. #15
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    Animation can consist of more then just scaling, rotation and translation which is why backed matrices are a must.

    Again, I'm not suggesting collada shouldn't store trans, rot and scale separately. I'm only trying to make it 100% clear the without the ability/option to export baked matrixes one per frame there will be cases where the animation in the 3D package will not match the animation reproducable in a collada file.

    I generally aim to avoid that situation with my exporters. I want the artists to have 100% control over everytihing with no limits or as few as possible. Baked matrices come close to this ideal. Anything else and I can guarentee I can give you a scene collada will not be able to reproduce.

  6. #16
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    Quote Originally Posted by greggman
    I'm only trying to make it 100% clear the without the ability/option to export baked matrixes one per frame there will be cases where the animation in the 3D package will not match the animation reproducable in a collada file.
    I accept that there are cases as you describe and that this needs to be handled using matrices.

    But an animation file which outputs a matrix per bone per frame is going to be massive compared to one that outputs (possibly) only a translation and rotation for each keyframe. So if the data does not require the first approach (and none of the character animations in any of the projects we are currently doing require it) we should not be burdened in this manner.

    The Collada exporter therefore needs to give the user the choice of using full matrix output, or translation/rotation/scaling inputs instead.

  7. #17
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    Aggred, if you are not using animations that need that info it would be a waste of data for you.

    But, I'd like to make a point here. This point is not collada related:

    I could be wrong but I'd be willing to bet that the reason your current projects are not using animation that requires matrices is specifically because your system doesn't handle them and therefore your artists have learned to live with the limitations of your system. I suspect they probably ran into issues where they made something in their favorite 3D package, exported it and found out that what they got in the game didn't match what they made in the package. They were most likely told "don't do it that way" and being powerless (they aren't programmers so they can't fix it themselves) they are being forced to do less than their best work and / or being forced to be inefficient, doing things by hand that would be done procedurally or doing without features in their 3D package that would let them get work done faster. Of course I could be wrong but you might want to ask them.

    We have no teamss here where we have not run into this problem. All the teams have learned to take baked matrices and compress into T,R,S and or curve fit or whatever else after it comes out of the 3D package. That way every single feature of the package can be used and we have far less complaints from the artist of the type "hey, why does that animation in the game not match what I made?"

  8. #18
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    Quote Originally Posted by greggman
    All the teams have learned to take baked matrices and compress into T,R,S and or curve fit or whatever else after it comes out of the 3D package. That way every single feature of the package can be used and we have far less complaints from the artist of the type "hey, why does that animation in the game not match what I made?"
    Why not doing this in the exporter ?
    Maybe this way you would not have to do anything after it comes in COLLADA ?

  9. #19
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    Quote Originally Posted by greggman
    I could come up with thousands of situations where keyframes will not handle the animation my artists make.

    All I'm asking is please don't make collada unusable by those of us that would rather let our artists do their best work.
    Keyframe animation is not the only kind of animation that COLLADA will support. Rest assured we are considering dynamics, morphing, skinning, mocap, particles and so forth.

    COLLADA design has been the result of collaboration and cooperation among the interested parties. Part of my job is to keep the designs moving and progressing until most everyone is happy with the schema. For COLLADA to succeed as a schema and as a project, we have to achieve consensus so that implementers will implement it because they helped design it. Users will use it because they helped specify it's requirements. COLLADA will be useful to those who contribute because we are listening.

  10. #20
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    One issue with wanting any other export format for animation than the vendor would provide is keeping a collada file as source material....

    For example, if you collapsed all the animation data to baked matrices per frame at whatever frequency, it might work the best for some. However, it would make it near impossible to reimport the file back into your content package of choice in an editable fassion. Factoring a prebaked matrix can be non-trivial if even feasible....

    Now that I think about it. This type of conundrum can occur with almost any type of data. Ease of interacting with data might not play well with the source data stipulation.

    Are exporters allowed to provide a separate export only format for things like this? Or are people expected to understand that they could lose information if they export and reimport using a custom format. The only way I can think of to solve this is to add the more helpful format as redundant data only for the user.

    I hope this helps...

    Adruab

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