View Full Version : Moving on a path

03-20-2005, 11:47 AM
is there a way when animating so I can have something follow a path. So all I have to do is control the speed of it. Like a rollercoaster? So I do not have to animate all of the wheels, only move the cart down the track. I am sure this there is a way to do this, does anyone have any advice?

03-20-2005, 02:12 PM
LW manual PDF Version Page 841/812:


Path to Motion takes a spline from modeler and makes it into a motion path for layout

Note in the manual it's Export Object as above but on the interface it's File/Export.

The Steps are pretty simple for the path part.

1) When your rolercoaster is done, select/copy one string of points along the rail's length on one vertice. What I mean is along one linear edge or corner of the rail's profile preferably the top and then along it's entire path. SO that you have one line of points to create a curve.

2) Paste these points into a new layer and reselect or just choose ctl. p (Create Tab/ Curves/ More/Make Curve/make open curve) if you choose the latter then just switch to Ploly Select mode and the curve should be seleted. Then paste it into a new layer.

3) with your curve path in the new layer select File/Export/Path to motion and it will make a motion file you load into Layout to animate the cars along the patch.

From here it gets even more fun.

Now you have to figure out how to have the other cars follow using the following tools:

Null objects
IK ( inverse kinematics) or
Apply an offset of to motion to each car or
IK Booster and even...
Using bones

In the bones idea there is a great video by Proton to downlaod on the Newtek site in the LW Video Tutorials.

But this will get you started. You can look this tuff up by category in the LW Manual.

As to the weels I have no direct experience with this though it is something I am going to research.

These are the areas I have in mind.

Object dynamics:


Both found under the Object properties (with currect object selected) in Layout under the Dynamics tab.

When you click on Add Dynamics chose each of these. When they are in the list double click to get the properties.

To get your "weels turning" as it were on all of this there is a Rotation tab under Hard dynamics.

It would be a good - afternoon or late evening or two - fun project to sit down with the manual, your favorite food or beverage and check this stuff out.

Thats what I plan to do.

Also before dynamics there were calulators. Someone in an old Lightwave Pro Mag (1995) published a tutorial on this- wish I would have kept it.

There is a simple formula that has to do with wheel radius/circumference/distance/time. Basically What distance are you covering over what time?

The variables are
Distance Traveled
Weel Circumference (= 1 360 rotation)

So: How many rotations per distance or how much distance per rotation? Either way. Then how far are you going to go? That equals how many rotations to get there. Then, over what time? Simple, how many frames.

In (A) frames we're going (B) distance. So there is a rotation of (C) applied to the last frame for that object.

As for speed changes you just follow your distance key frames with your rotation key frames and use the same ease in and ease out curves.

Now if you can figure that out on a curved surface/path you are in.

If you are real handy with math you can figure it out.

Perhaps someone has light to shed on this.

Now all opf that said, I have seen mention on this forum to plugins that calculate this. So, hey, mabye you wont have to drag out the old calulator after all.

Happy costering


03-23-2005, 06:08 PM
Thanks for your help. When I get to that point I am make sure and post something here to show how you have helped.
Thanks again!

03-23-2005, 07:21 PM
No Problem.

By the way I posted the formula for turning weels. Also I can show you how to figure out the distance over the curves of the rails too. That one is easy.

When you clone the rails to make the track you can easily know the distance between each because you'll be entering it or you can later measure. (They'll all be the same I assume) If not you can still figure it out roughly.

Just count the number of rails and times the distance between each will give you the distance along the curve.

Maybe there's a more high tech way to calulate it but that will work - even on an ilsand with no electricity.

Have fun,