Rigging a sperm tail

Become a member of the CGSociety

Connect, Share, and Learn with our Large Growing CG Art Community. It's Free!

 
Thread Tools Search this Thread Display Modes
Old 05 May 2014   #1
Rigging a sperm tail

Anyone have any idea how to rig something like this?

SPERM MOVIE

I am guessing it uses some kind of formula to get the motion of the tail flowing in that helical motion. I am terrible with math so any help would be greatly appreciated!

I am guessing there is a dynamics tag in there too so that the tail can collide with other objects...

Also some of the rigging on this...

OCTOPUS RIG

how do you learn how to do this kind of advanced rigging?

Hopefully someone can shed some light on it.
Thanks!
 
Old 05 May 2014   #2
Howdy,

You could use the formula of a sin wave:
amplitude * sin(speed * frequency * time)


... which is what I used in this simple camera shake Xpresso setup:
http://www.cactus3d.com/CameraShake.zip

Adios,
Cactus Dan
__________________
It doesn't matter what people say about you, just as long as they're talking about you.

cactus3d.com, cactus3d-Plugins, CD Character Plugins forum
 
Old 05 May 2014   #3
Thanks for the file and the tip Dan, I guess I am still a little confused as to how you would apply that to drive the motion of a joint chain?
 
Old 05 May 2014   #4
Howdy,

Try this simple setup:
http://www.cactus3d.com/SinWaveSpline.zip

Adios,
Cactus Dan
__________________
It doesn't matter what people say about you, just as long as they're talking about you.

cactus3d.com, cactus3d-Plugins, CD Character Plugins forum
 
Old 05 May 2014   #5
The motion of sperm tails is helical, as in that demo movie you have, but their "heads" do not stay still: they rotate along with the rest of the body. This is easy to see in good video micrography (though you can sometimes see unnaturally constrained sperm (under a microscope slide, for instance) appear to have "still heads"). The head rotation is actually an important part of how the "spade-shaped" head of the sperm digs through the zone pellucida and fertilizes the egg.

Here's an example file with two simple rigs: one a sperm model with a spline deformer pointing at a rotating helix, and one rigged with joints with dynamics turned on. I'm not sure at this point how to add the collision dynamics, but is that necessary in your situation?

https://www.dropbox.com/s/y0nyyrmij...d_sperm.c4d.zip
 
Old 05 May 2014   #6
Thanks for the additional files and info! It certainly gets me going in the right direction.
I don't really need the collision but I thought it was a really nice touch to the rig!
 
reply share thread



Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
CGSociety
Society of Digital Artists
www.cgsociety.org

Powered by vBulletin
Copyright 2000 - 2006,
Jelsoft Enterprises Ltd.
Minimize Ads
Forum Jump
Miscellaneous

All times are GMT. The time now is 07:03 AM.


Powered by vBulletin
Copyright ©2000 - 2017, Jelsoft Enterprises Ltd.