Distance based wheel rotation animation

[ticosimmer]

Hi,

,I've been looking all the web for a solution to the following problem.  I followed the "3Ds Max Animating a Car Path-Spinning the wheels" tutorial.  Everything is ok, except that the wheels spins at a constant speed, no matter how fast or slow the car advances.  I'm looking without success how to solve this issue.  The method is based on wire parameters with a path percent.  Is there a solution?, please.  I'm trying to make an animation of a car on a path with spinning wheels, but the car must slow down or even stop at road crossings and the wheels must spin or stop accordingly.  Please help

 

[leeminardi]

Place a Position List controller on the car then add a Path Controller. Create an expression controller for the rotation axis of the wheel as a function of the path percent. 

For example, in the following the wheel's (cylinder001) Y axis is the axis of rotation. It is linked to the chassis (box001) which has a Path Constraint controller. The variable box1PC is assigned to Box001/position/path-constraint/percent.  The multiplier  (10 in my example) will need to be adjusted to work with the radius of the wheel.   It is (path length)/(pi*wheel dia).  You can find the length of the spline by selecting it and then going to the utilities tab, measure. 

You can keyframe the percent along the spline to make the car go fast, slow, backup, or stop.

[ticosimmer]

Thank you very much for your help.  I found another way just yesterday.  The tutorial https://www.youtube.com/watch?v=3uFJ02KFsIg

does not indicate that if you make changes in the animation after you have entered the wire parameters formula, you need to update it for all 4 wheels.  So I would recommend to first of all, create the animation points, with stops, turns etc.  then follow the last part of the tutorial to link the main helper to each wheel, and then insert the percent formula.  Doing this, the wheels will spin at the correct speed, slowing down and even stopping spinning according to the animation requirements.  Cheers

[leeminardi · Accepted solution]

Either wire parameters or expression controllers can be used to do what you want.  I tend to go with expression controllers as I find them more accessible and able to use multiple objects (not needed in your task) as well as having some debugging features not available with wire parameters.   YOu should be able to modify the motion (as long as the path length stays the same) after you rig the wheel no matter which approach you use.  You can link the other wheel rotations to the rigged wheel with wire parameters although technically all 4 wheels do not spin at the same speed when going around a corner but no one would notice the difference!