View Full Version : A poor man's turning wheels

03-23-2005, 06:38 PM

03-23-2005, 07:43 PM
Jonny Gorden supplied NewTek with a great scene that ships with LW8 that has a car with turning wheel using expressions...it does a whole lot more...brake lights, squash and stretch, etc.

check it out!

03-24-2005, 02:37 AM
Yea I figured you could do it. I just haven't gotten to that part yet.

Very cool. I'll sink my teeth into it when I get to Layout. Just now getting my head above water in Modleler.

Thanks for the tip!


03-24-2005, 11:24 PM
Another real simple way is to rotate the wheel(s) and then use cycler to spin the tire wheels based on the motion of the car or some other control object.

03-27-2005, 01:15 AM
Hey Thanks Lary.

I have no idea what cycler is yet but I've seen it in an expressions sample scene in Layout. I'll get to it soon enough.

BTW I''m reading 1001 tips and tricks and I am really enjoying your entries. I strongly recomend this book to anyone!!

I found that formula on Pg. 109 of the book - an entry by Robin Wood.

The formulla is : C=(a symbol I have no idea what it means or does) then D.

This formula - which by the way is not explained in this tip - adds up to a wheel with a diamiter of 1m will travel 3.14159m in one rotation. If you apply my calculation above (using 500m radius - 1/2 of the 1m diameter )it comes out to: 3150. A nice pretty, round figure. Isn't it?

Pretty close.

Actually I was vassilating between a figure of .0174 and .0175. My measurement was somewhere inbetweeen and I figured a little boost because of the curve, so I took .0175.

But if you refine my figure to say .01745 it returns a figure of.



Ah threr'es the difference for the curve! Only that much. .00059

Now thry this:

(obtained of course by "reverse engineeering" the 3.14159)


It returns:

3.14154m distance in one rotation

Pretty **** close!

For those of you following at home - you can see how swimmingly popular this thread is - and to save you from going back up the page it is:

A radius - I prefer radius because that is how you are usually making a round object in modeler by the radius - of 500mm X.017453 gives you the amount it will travel in 1 degree of rotaion. I prefer this 1 degree figure because even in the formula above it still has you having to do more math.

That one degree of rotation is 8.7265 This figure is your hollygrail, not the 3.1459m that the above formula returns.

Why? Because you still need to figure out how much rotation to type in the rotation field in Layout based on your distance.

The weel travels a distance of 10 m translate that of course to 10,000 and now devide by 8.7265(1 degree of distance) to get the exact number of degrees to type into the field:

1145.93 degrees.

I'll bet there is a way to calculate it differently using the formula but it is probably a mind-numbing ***-backwards way to look at it. (Most higher math is to me)

I prefer this because it follows the logic you are trying to deduce with a simple direct understandable formula.

Sure you can do it with expressions or with cycler. Assuming you a) even understand the math in the formula and b) have the time to figure out those other tools.

My point here is only a quick and dirty crack open layout and get your wheels truning, that's all.

Something you could figure out in 15minutes time if you thought about it. Now you don't have to.

While you're waiting for the wheel-turning scene to render for your client, you can crack open the manual and figure out these other ways that are obviously much more flexible and dynamic. It's just that they will take time to figure out how to use.


03-27-2005, 01:46 AM
Thanks MDust. Its a great book. I had a lot of fun writing for it as well.
The nice thing about cyclist or cycler is that you just have to rotate the wheel once and then let the controller object determine how it turns....no math involved :)

03-27-2005, 04:01 AM
Glad you had fun with the book. I am learning tons!

Yea I'm totally down with Cycler or cylist or whatever you call the dang thing. In fact I saw you mention it in another post. To show you my ignorrance, I thought it was a plugin - er third party plugin.

But I'll look it up - well actually, I just got done with my first time through the Modeler section of the manual and I'm going to be practicing the tools there for a while before hopping over to the Layout side.

So my only question is: is it really a one two snap, that is to get it done with this tool? Or would a person have to really dig into the manual and kind of put it together? (I'm trying to catch up from V.4 and part of 5!!!!)

You know what I mean? I mean are the steps really 1, 2, 3 or is the tip your giving here assuming a person needs some other background in how certain "advanced" layout tools and functions work?

If the former is the case lay it on us and I'll just delete all of that other math balderdash. (A tutorial perhaps?)

Otherwise I was going to wait until I figured it out and update the post - but that could be a while.


03-27-2005, 06:45 AM
I was wondering how long it would take... for someone to share that it's a bit easier than you described. But, no one ought to discourage you from such scholarly pursuits. :p

Yeah, it is that easy. Clickety click. The hard part is figuring out who/what should be following who/what.

If it's a deep hierarchy, the built-ins will fail on you. Relativity, though a third-party app, is the only solution at that point.

{Soapbox Rant: I can only dream of where LW would be today were Relativity made the native expressions engine instead of the three that are native. As a semi-literate programmer, Relativity is much easier to comprehend. }

03-27-2005, 12:10 PM
I was wondering how long it would take... for someone to share that it's a bit easier than you described. But, no one ought to discourage you from such scholarly pursuits. :p

Yeah I know I was wondering the same thing! I find it as equally humorus. I had the same thought. People are just sitting back thinking "go ahead, let him try and figure it out...he he" I do think these kind of things spark the imagination though.

Although why would the formula be incuded in a recent 1001 LW tips?

Still waiting on the clickity click part though, so I can let this message self-distruct.

Or is there an equal amount of humor in letting my **** hang out in the wnd even longer. ... er further... er there's no good way to say that is there :D

A simple 123 tut would be great.


03-27-2005, 06:43 PM
Touche. And yes, your arse hung out there to LEARN, though a humorous image, can't be pleasant from your perspective.

What books do you have? I think it was in 1001 because people still ask about it.

The two methods I'm used to are: one from Dan Ablan's LW[6] and Relativity's instructions/tutorials. Both base their results on the circumference of the wheel; once that's know, you can device, as you have found, follower and cycler type plugs to have it repeat that ad nauseum, based on the movement of some item.

I found these over at http://flay.com with a search for wheel:

Surely that helps your arse in out of the cold? :D