[x3d-public] Fw: Re: Blend Shapes and x3d Animation tools

[John Carlson]

Possibility: Adding a coordIndex more than once in an HAnimDisplacer.  Just
define what it means when a coordindex appears more than once.

Possibility:  change the displacements with another interpolator.

John

On Sun, Oct 27, 2024 at 6:27 PM Joe D Williams via x3d-public <
x3d-public at web3d.org> wrote:

> More to mention some ideas about Displacer. Again, I am thinking that the
> x3d CoordinateInterpolator deals with the entire, all points, of the shape,
> while the Displacer can move one or more points in a defined direction
> under control of a scalar 0 to to 1 input.
>
> The CoordinateIinterpolator provides a complete set of coordinates, a
> keyValue, for each key time.
>
> The Displacer provides a 3D vector, the displacements, for each point, the
> coordIndex, of the point to be controlled by the 0 to 1 scalar input, the
> weight.
>
> So, when is the CoordinateInterpolator preferred over Displacer?
>
> Well, first is that for the Displacer, we get a linear  interpolation for
> movement added by the weight. This means if you don't wish a linear motion
> with a linear weight input, then we must adapt the weight input to the
> motion curve we wish.
>
> Same for the CoordinateInterpolator if only two keyValue fields are used,
> one for time0 and one for time1, with a standard time input, we would get a
> linear interpolation, or the 0 to1 fraction_changed input could scale the 0
> to 1 input to achieve a custom deformation curve, as with the Displacer.
>
> However, what if the vertex movement may not be totally composed of a
> linear motion, but is a real 3D curve in time and space? With x3d Humanoid
> we have some choices.
>
> First, an example  of a humanoid eyelid where the center of rotation and
> desired arc is well  understood. Here a simple choice is to bind the eyelid
> vertices to an eyelid joint, then rotate the joint as required to produce
> the desired movement.
>
> Also,, a coordinate interpolator can be used, but containing several
> keyValue sets list to produce the motion. Probably at least one
> intermediate set of points.
>
> Next, it might be unlikely that the Displacer as is specified now could
> handle this motion of an eyelid that is by its std orientation and path,
> probably following a curved path in Y and Z. Since the displacer only can
> deliver a varying magnitude of a fixed orientation vector then a motion
> curve for a point in more than one direction may not be possible.
>
> One added point I learned is that the Blender Relative mode can accept the
> weight input greater than  1 and less than zero and the tool will
> extrapolate along the  given vector. This can be very useful, it might
> seem, for when we want to reuse a Displacer and it is similar enough to
> another and we could just change the input scale say from 0 to1 to 0.05
> to1.25 without having to edit the actual set of vectors. This sounds easy
> and convenient but probably has some down sides in a close simulation. I
> think we could recommend a differnt sort of hackforthis.
>
> While the Displacer is offered as a substitute for coordinate
> interpolators and reall canhelp tosimplify the user code in many
> situations. So,realtime runtime.
>
> Does this set of features offer the opportunity to think about how to
> update the Displacer?
> For example
> (1) to allow multiple keys and vector sets so that more complex point
> motions can be presented? How about
> (2) extending the weight input range to less than 0 and greater than 1 and
> the runtime extrapolates?
>
> Thanks and Best,
> Joe
>
>
> -----Original Message-----
> From: Joe D Williams <joedwil at earthlink.net>
> Sent: Oct 21, 2024 5:07 PM
> To: <x3d-public at web3d.org>, <hanim at web3d.org>
> Subject: Fw: Re: Blend Shapes
>
>
> -----Forwarded Message-----
> From: Joe D Williams
> Sent: Oct 21, 2024 5:04 PM
> Subject: Re: Blend Shapes
>
> Just as an update to this, in Blender we see BlendShapes in two styles,
> Absolute and Relative.
>
> BlendShapes Absolute presents the process of a CoordinateInterpolator that
> deforms or morphs the complete mesh, by allowing author to create a base
> mesh, then additional mesh shapes times for the complete shape moves from
> the base shape through various key shapes with intermediate values allowing
> several styles of interpolation.
>
> BlendShapes Relative allows picking out all or a subset or mesh points to
> be moved relative to current mesh points location according to a scalar
> input.
>
> So, the only difference between Blender and X3D is the style of naming the
> values. .
>
> BlendShape Absolute, it seems like internal data for coordinate points,
> the X3D keyValue field, and the timer, or weight, the X3d key, could be
> easily exported. the big problem is that Blender allows several
> interpolation maths other than linear. Is it time to intrudce other
> interpolation maths to X3D?
>
> BlendShape Relative, the Blender data is basically the same as for X3D
> Displacer, consisting of a the list of mesh indices to be operated on, a
> corresponding list of 3d vectors to be drawn relative to the current mesh
> points, and a weight input. the biggest difference in the Blendier
> implementation is that the weight is allowed to be less than zero and
> greater than 1 and the Blender tool does extrapolation to find the actual
> value. This weight overrange feature could be very useful when adapting one
> setup to another in a similar setup.
>
> Thanks and Best,
> Joe
>
>
> ---Original Message-----
> From: Joe D Williams
> Sent: Oct 3, 2024 11:03 AM
> To: Myeong Won Lee , Brutzman Donald (Don) (CIV) , ,
> Cc: WILLIAM GLASCOE , , , Joe Williams
> Subject: Blend Shapes
>
> As we hear more of high level authoring systems used in entertainment,
> such as USD,we encounter the term Blend Shapes or blendshapes, etc.
> Under the covers this is an alternative to skeleton-driven deformable mesh
> animation where the points are moved according to a weighted function that
> takes into consideration the motion of associated Joint nodes that could
> produce direct action on a vertex.
>
> Dependence on this style for detailed animation of individual points or
> groups of points results in networks of skeleton hierarchy rigs in order to
> produce shape deformations like lip movements or other muscle simulations.
> Overall, these structures are interesting and can solve some interesting
> mesh animation problems it becomes difficult to produce standardizable
> compositions.
> Besides, a better tool that can operate with or independently of the
> skeletal animations.
>
> One obvious solution is to add CoordinateInterpolator(s) to move points of
> the mesh. Here the basic problem is that you must
> deal with the entire target mesh for every key and it becomes a special
> case to combine the effects of multiple interpolators on the same mesh.
> I think the basic two ways to think about it is the idea of working with a
> complete mesh and/or just some part(s) of it, a sparse set, an area of
> points of the same target mesh.
>
> In reality, you want these skeleton-driven and these additional
> independent deformations to be summed so we get the complete animation.
> For instance we would say that for each frame, animation produced by the
> added displacements are added after all skeleton-driven point animation is
> complete.
>
> So, with this problem of simulating geometry and parts of geometry
> morphing from shape to shape under control of some set of Joint nodes along
> with producing surface movements more or less independently while
> innovating a design that gets rid of cumbersome Coordinate Interpolator
> operations, HAnim documented an animation form that lots agreed that this
> was a best practice, easily standardizable technique.
>
> interface Displacer {
> coordIndex [ list of indices ]
> description "Some Functionality"
> displacements [ list of 3D vectors ]
> name "required name"
> weight 0 }
>
> The coordIndex field contains a list of all coordinate index values of the
> target mesh be animated by this Displacer. The index is the order in which
> the point to appears in the user code. If only points 57, 58, and 59 were
> to be animated then the coordIndex field would be:
> coordIndex [56 57 58]
>
> The displacements field contains a list of 3D vectors that represent the
> maximum movement from the default or magicallly enough whatever the current
> location of that point is. Now, to master this you must understand that a
> point has its own local coordinate system. Like the default coordinate
> system of a Joint, a point in default, before animation, is the same as its
> parent Joint, 0 0 1 0]. This means that let's say that those three points
> are the tip of a finger and the objective is to move those points directly
> outward 0.01 unit then the vectors would be:
> displacements [0 -0.01 0, 0 -0.01 0, 0 -0.01 0]
>
> Now the weight field receives a 0 to1 floating point value that linearly
> scales the output vector. If zero,then no added movement; if 0.5 then
> one-half,and if 1, then maximum. If 1 is received,then the point will be
> moved -0.01 unit in the point's Y-axis of the geometry coordinate system.
>
> A way to compute the displacements value is if you happened to have a
> CoordinateInterplator you wanted to get rid of is to find the coordinates
> of the point at minimum, key input 0, and maximum, key input 1, then find
> the 3D vector that connects those locations. If you are finding these
> values by examination, then a major consideration is that you want to set
> these up understanding the default point coordinate system.
>
> So, finally,why did HAnim call it a Displacer? Well, there were a couple
> of names offered and the HAnim folks just had to pick something different
> from anyone was actually showing. The idea of a Displacer is very clear,
> you are telling it to displace a point from its current location in some
> direction relative to its default coordinate system.
>
> In summary, seems to me the idea of terms I have heard like deformer,
> morpher, blended shapes, and others all can be represented by the
> functionality of HAnim Displacer. I hope that is good news.
>
> Thanks and Fun,
> Joe
>
>
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>
>
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