Bryan Heit wrote:
> I am trying to create an animation of a leukocyte recruitment cascade, 
> which in plain English is the process by which immune cells leave the 
> blood in order to enter tissues.
> 
> Any way's, I've got the whole thing pretty much done but I've run into 
> one problem which I cannot seem to lick.  At one step of the process the 
>  cell I'm modeling has to squeeze through a narrow gap.  The best 
> description I can think of would be squeezing a water balloon through a 
> tube which is smaller then the balloon.  So you'd start with a sphere on 
> one side of the "tube", mid-way you'd have two equal sized spheres on 
> either side of the tube with a connecting "neck", and finally you'd end 
> up with a sphere on the opposite side of the membrane.
> 
> The only way I've been able to model this in povray is to use blobs; 
> this was animated by slowly expanding the size/strength of an invisible 
> sphere to "pull" the other sphere through the gap.  A couple of 
> negative-strength spheres maintained the proper "neck" size.  While this 
> achieves the effect I desire I end up loosing the internal structure  of 
> the cell.  To try and keep the image of this structure, I tried mapping 
> a JPEG of the cell onto the sphere representing the cell, but it ended 
> up being so distorted as to be pointless.
> 
> I also tried using the blob command to "pull" my cell through.  My cell 
> is defined in a separate .inc file as a union of various basic shapes 
> (plus some media, etc, to make it pretty).  I tried to use the cell 
> union as the visible part of my blob, but this didn't work as blob 
> appears to be limited to simple objects.
> 
> Does anyone know of a way to achieve this effect?
> 
> Thanx in advance
> 
> Bryan Heit
Maybe a job for MegaPOV's Mechanics Simulator?  I have almost no Idea 
how you'd do it, but It's at least worth looking into.

Sorry I couldn't help more.

A.D.B.

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