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26 Dec 2024 10:20:30 EST (-0500)
  animate a verigated ribbon (Message 1 to 2 of 2)  
From: Leef me
Subject: animate a verigated ribbon
Date: 14 Feb 2007 17:25:01
Message: <web.45d38b5eb3638a1ced05561a0@news.povray.org>
I want to create a shape, such as a gift ribbon of fixed length.
With color that varies along the length of the ribbon.
And give it a curved path in 3D.

Further, I want to animate the path of the shape, with the above color
variation following the path of the ribbon as the ribbon moves.

I am reading through the documentation as time permits because I have other
projects in mind, but could use a little information toward this goal.


Has this already been done? If so, would someone provide a reference?
If it hasn't been done, are the following sections useful to the task?


"1.3.1.4 Sphere Sweep Object" promising except it is a sphere instead of
flat
"1.3.1.5 Bicubic Patch Object" seems promising for the object
"2.2.1.9 Spline Identifiers" possible way to define the path

Thanks in advance
Leef_me


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From: Charles C
Subject: Re: animate a verigated ribbon
Date: 15 Feb 2007 01:10:01
Message: <web.45d3f7ef792a9a1632e613b0@news.povray.org>
"Leef_me" <nomail@nomail> wrote:
> I want to create a shape, such as a gift ribbon of fixed length.
> With color that varies along the length of the ribbon.
> And give it a curved path in 3D.
>
> Further, I want to animate the path of the shape, with the above color
> variation following the path of the ribbon as the ribbon moves.
>
> I am reading through the documentation as time permits because I have other
> projects in mind, but could use a little information toward this goal.
>
>
> Has this already been done? If so, would someone provide a reference?
> If it hasn't been done, are the following sections useful to the task?
>
>
> "1.3.1.4 Sphere Sweep Object" promising except it is a sphere instead of
> flat
> "1.3.1.5 Bicubic Patch Object" seems promising for the object
> "2.2.1.9 Spline Identifiers" possible way to define the path
>
> Thanks in advance
> Leef_me

If it were me, I'd go with a pair of splines (one might be generated off of
the other) and use a macro with a loop to lace triangles between the two.
Making the colors different as you go down the curved path would be easy in
this way.

For the animation, do you want the ribbon to move along like a train or like
an articulated tentical?

If like the train, that can be done by sliding the triangle-laced ribbon
further along an extra long spline path.

If like the articulated tentical, you might have to get into keyframing...
Put the spline data into an array and make a macro which can convert, say,
an array of 4d vectors into a spline.  Make another macro which can
interpolate the x,y & z values between two arrays of vectors.  Thus, each
array represents a keyframe.

If you do go with splines, there are some spline editors which might be
helpful but I don't remember what they are... I do mine manually.

Charles


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