Car tires

[Devin Johnston]

Hey guy's I'm done a few animations where I have cars driving by and I can't seem to sink up the wheels spinning with the movement of the cars. Can anyone give me some tips on the best way to do this; oh I'm using Max 9.

[batteryoperatedlettuce]

I'm guessing here, but if they are cars set to a path, you could:

 

a. = length of path/circumference of wheel = number of rotations.

b. = script the animation so that the local rotation of the wheel is proportional to the percentage of distance traveled on the path.

 

If you sit tight for a while, I might even write the script... unless someone has a much better idea

 

-edit: oh, if you're a fan of reactor you can read about/use the wheel constraint

[vizfx]

Hi

The first choice is ToyCar from Reactor toolbar (see help). The other one more advanced is a plugin from http://www.craftanimations.com which is extremely powerful – you can even record an animation with input from joystick, even 2 simultaneous.

Best regards

Mihai

[neil09]

May be using wire parameters can help you out....

[RyanSpaulding]

I'd measure the care tire completely, then measure your path, then have the tire rotate that amount of times. Should work conceptually...but I'm not on Max.

[Devin Johnston]

Thanks Ryan that's what I wound up doing, everything else was just to complex for me right now.

[pailhead]

There is a simple way to solve this with expressions. Create a clynder to serve as a dummy for the wheel and a box to serve as a dummy for the car. Add a list controler, and then add a bezier (or linear or whatever) and an expression controler to the wheel rotation axis.

 

In that expression click on vector (or something like that, there is a list where you can define scalar and vector values) and find the box position value.

 

Now the expression should go something like this, BoxPosition.x/radius (wheel). This will give you the value in radians which will make the wheel turn.

 

It's been a while since i've done this, and it's actually been a while since i've done any math at all, i don't have 3dsmax right now so i can't test it but i will when i get back home. You can fool around with this though, you will probably make it work.

[neil09]

Hey Dusan, I tried to follow your suggestion but cant understand fully. Can you explain in bit detail...

[Tommy L]

A rather sly work-around is to make the wheel spin slowlyBACKWARDS. Then it looks like the optical illusion you get when a wheel spins anyway. Doesnt work too well if the cars slows to a stop close to the camera though.

[pailhead]

It's simple, if you know what a radian is. Basically, if a car should move by a radius of it's wheel, the expression car.movement : wheel.radius would equal a radian. A radian is the default unit for rotation in max.

 

It's just a matter of writing that expression, it should be really simple but i'll have to check how it goes.