View Full Version : How do i animate sperm?

08 August 2005, 03:39 PM
Ive modelled one sperm but i dont know how to animate it, can anyone help? basically i want to animate to swimming towards a sphere(this will be modelled into an egg cell at a later stage) and i want the correct looking motion of its tail and head, so does anyone at all know how to acheive this?

08 August 2005, 03:46 PM
i really dont exactly know how they move,but i'll give you some hints////
there are several ways
one of them is to take it and turn it to softbody and then apply a turbulence or air or other stuff (combination is better ofcourse) and that's it,you can animate it just movint through that sphere.
or.....animate them with a blend shape and then use a particle emitor....(Instancer)
as i said,there are several other ways....Think of something.:thumbsup: it's easy....

08 August 2005, 03:51 PM
the first thing that came to mind when I read you're post was, maya's hair dynamic system, it's very easy to use, and you get really good animations with almost no work.

08 August 2005, 05:17 PM
Spline Ik on tail, sine wave expression used to drive locators which control curve's motion. Use velocity or Z translate to determine speed of sine wave. Add in noise to jitter it.

08 August 2005, 05:42 PM
Thanks for all replies so far but in regards to mayas hair system i only have maya 5.0 unlimited. And how exactly do i apply a sine wave expression to the Spline IK locators? do u mean sine deformer? i dont know how to create a sine wave expression :(

08 August 2005, 06:06 PM
Spline IK is good too,Bonedaddy is right. But it is something you have alot more control over it,more accurate i mean too.
about the expression...i'm not quite sure if it's what he meant but i'll give it a shot.
you can create a locator or a cluster and then Control their local position by a wave Expression which is smiliar to something like this : Locator1.positoin=<<0,sin(time),0>>
it depends on the direction it is going to. And then i think you can group that locator to move it with the whole other stuff though i havent tried that one yet,maybe you should use another expression.

08 August 2005, 06:08 PM
ow,i rememberd something
you should add =+ instead of =

Someone Correct me if i'm wrong

08 August 2005, 06:12 PM
i guess all of them are should add a variable which just control one Axisanyway,i'm waiting for other replys

08 August 2005, 12:02 PM
Ive modelled one sperm but i dont know how to animate it, can anyone help? basically i want to animate to swimming towards a sphere(this will be modelled into an egg cell at a later stage) and i want the correct looking motion of its tail and head, so does anyone at all know how to acheive this?

IK spline seems the right tool for it, as I think someone else suggested too. You can then use the particle instancer to make duplicates of one sperm.

08 August 2005, 11:14 AM
you can also have a ikSpline and apply a sineDeformer to the's a cheat but it works..

08 August 2005, 01:51 PM
How about using more of a rotating corkscrew/helix model. I would think it would be easier and also more physiologically correct.
Sea Urchin demo:
And the infamous:

08 August 2005, 08:37 PM
oddly enough I had to rig a spem a few years back for a short. To get it to swim I also used the sin wave deformer on the Spline IK curve trick ( make sure the deformer doesn't affect the 2 base points at your tails base ).

I went a step further and instead of deforming the Spline IK curve directly I duplicated the spline IKs curve twice and made the duplicates blend shape targets for the Spine curve.... then applied the sin deformer to one of the duplicated target curves and attach controls to the other duplicated curve. This will allow you to blend between a full auto swim and controled posing.

Also know that to get the sin deformer to update you need to set one of the sins attributes = to time. I did it with and expression and if I remember correctly it was the sin's offset channel that I did this too.

Good luck there,


08 August 2005, 11:38 AM
in maya you can rig a hair follicle spline . the cool thing about it is you can get it to react dynamically but you can also apply the blendshaping suggestions by manipulating the REST curve of the follicle.

As well! the hair system reacts to dynamics.. so you can put an air field to blow it and then rotate the head in such a way as to get a helical motion.. I think that could be a good over-all approach.

here are some examples (scene file is attached) ( (

the first example is with an airfield and a sinusoidal motion applied to the control, but as I say, it can also be done with a deformer. anyway, that's my $.02

08 August 2005, 11:03 PM
sheesh, I didn't read you've only got maya 5 unlimited.

You're not limited.. LOL you can simulate the hair follicle thingy using a soft curve.. that way you get to have a curve for animating (the goal) and another curve to react to dynamics.. now it's not perfectly identical, but it's similar.

Actually I'm quite pleased with the way it's turned out.. but you should judge for yourself. it took forever to make it compared to the hair, because I had to set all the goalPP values for every CV by hand ( wrote a script in the end)


oh crap you need a maya 5 file don't you?.. so the ma file should work with maya 5, and there's an mb file for maya 6, I think it will work.. this is using soft bodies as opposed to hair.

08 August 2005, 02:38 AM
I don't know if this is a bit late to help but, you could generate a spiral curve, use that as a spline IK, then simply rotate it. That would give you the proper way that the tail moves, which isn't really a sine wave, but a constant turning corkscrew effect which looks like a sine wave. Obviously the membrane doesn't turn, but there is a "core" to the tail which does. At the root of the core is this wierd little molecular motor that actually turns it - kind of like an electric motor. Adding some sort of bend deformer to the spline would give you a bit of flexibillity too.

Although the little movies you've got are pretty cool...

Hope that helps.

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