Bryan Heit <bjh### [at] NOSPAMucalgaryca> 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.
.....
> Does anyone know of a way to achieve this effect?
.....

Yes, I believe that I do. But it's a lot of work.

If you model your cells as meshes, then you can use functions to deform
them.

Just feed the x,y,z-coordinates for each triangle corner together with the
time into 3 functions, one for each axis;

x_fn(x, y, z, t), y_fn(x, y, z, t) and z_fn(x, y, z, t)

So if you have a point with these coordinates:

<x0, y0, z0>

- then at time t0 its new coordinates will be:

<x_fn(x0, y0, z0, t0), y_fn(x0, y0, z0, t0), z_fn(x0, y0, z0, t0)>

The 3 functions above can (for example) be Bezier functions or some other
polynomial spline functions.

I once used 3 NURBS functions to deform a mesh object in an animation:

http://news.povray.org/povray.binaries.animations/thread/%3CXns935EBDC874F49torolavkhotmailcom%40204.213.191.226%3E/
http://tinyurl.com/dqsat

--
Tor Olav
http://subcube.com

Post a reply to this message