View Full Version : Is there a way to animate velocity?

09-12-2009, 03:13 AM

I need to do an animation of a little voltage measuring gague with a needle and a spinner. As the needle rises, the spinner spins faster.. As the needle goes down, the spinner slows down.

Is there some plugin, motion modifier or channel tool that lets me animate an item by specifying it's velocity??

The closest thing I could find was Worley's Polk plugin.. It has a "Vel-Accel" plugin. It gets me halfway there.. I can use one null to be the velocity of another null.. but to slow the velocity down, I have to animate the controller back in the opposite direction to subtract velocity and it's not very easy (if impossible) to get it to stop dead.


09-12-2009, 03:33 AM
Nevermind.. I've found a way to work it with Vel-Accel.

09-22-2009, 07:36 AM
mind to share ? :)

09-22-2009, 07:44 AM
Umm.. Well the plugin only works for position.. not rotation, so I made a null that it gets applied to, then an expression puts that null's position into the rotation of my spinner.

The tricky part is then using another null for the control item for VelAccel. OK so that part isn't so tricky, but the trick was how to animate it. I wanted to be able to speed the spinner up, then slow it down to a stop. But there is no provision for that.. Doesn't work that way.

So I animate the controller null in a smooth (1 on the tension keys) ramping up value, but then when I want it to stay at a certain speed, I add a stepped key bringing it back down to zero. So the controller null jumps back to 0, and no more accelleration is added to the continuously drifting null with the VelAccel plugin. Then to slow it down, I add a smooth curve in the opposite direction, followed by a stepped key frame bringing it down to 0 once the spinner was brought to a complete halt. Getting it to stop is more precise and you have to tweak it a few times to get it perfect.

09-22-2009, 08:02 AM
i am just doing similar task where i want tyre to wobble while car is driving... wobbling should be more aggressive when car is faster and when it stop it should stop wobble at last wobble position... etc.. something like oscillate but with frequency controlled by velocity.. if velocity is higher the higher is frequency of oscillation... got an idea ? :)

09-22-2009, 08:27 AM
So the faster the tire spins, the more it rattles? That's a tough one. If only I knew how to program in LW. Someone showed me the ropes in Flash and I went on to make some cool programs in it. But I don't know how to get started in LW.

09-22-2009, 08:30 AM
:) hehehe well i spent quiet of time now.. and i also wish to know programming ....

09-22-2009, 08:30 AM
You know... If you have Polk, it MIGHT be possibly to marry VelAccel with another of the plugins.. like blink or one of those other similar looping action plugins.

09-22-2009, 08:42 AM
dont own polk :( but i think it wouldnt change much... if there is just one plugin that can take data out of VELOCITY in some range... 0-1 for example i could use it easy with expression for frequency of oscillate... dpont for the rescue ? :)

09-22-2009, 09:59 AM
If you're on LW9+ you might be able to use Relativity. It started out as a 3rd-party plug-in expression system but now it comes with LW.

For the wobble, you might just try making a morph of the wheel that's skewed... or just parent the wheel to a null and the null to the axle. As the speed increases, turn the morph up or slightly rotate the null to put the wheel off balance. Of course, you'd need an expression or something to control that if you want it to be done automatically.

09-22-2009, 10:53 AM
that;s the point :) i want it automatically and every single expression follow only common channels and noone of them velocity (speed) channel :)

09-22-2009, 06:11 PM
you're not alone my friend. I've been fighting for this for some time now.
this thread (and our friendly and helpful mr dpont) may help you