CGTalk - Tank Tread Problem

dave_baer

03-17-2003, 04:51 AM

Ok, Im trying to create a tank tread.
1. I create a Nurbs Circle with 24 sections and form it according to how I want the tread to look.
2. I attach the tread using ANIMATE > MOTION PATHS > ATTACH TO MOTION PATH.
3. I adjust the position of the tread to line up correctly as it attaches in an off angle.
4. To duplicate the tread, I go to ANIMATE > CREATE ANIMATION SNAPSHOT > OPTION BOX and set the fields to achieve the desired results.

However, I get the following result:
http://www.fraghq.com/brainswell/treads2.jpg
The treads on top are fine while the treads on the bottom are reversed.

Any ideas?

Nicool

03-17-2003, 04:48 PM

Search on highend3d.com the "gmax" replies... You should found find something about the tank setuping maybe:rolleyes:

SheepFactory

03-17-2003, 05:14 PM

turn on follow!

set the world up type to Object up , inverse up if object flips , than do the snapshot :thumbsup:

dave_baer

03-17-2003, 05:58 PM

Nicool: A little more info please. How about a link? I searched "gmax", nothing comes up about tank treads.

Sheep factory: I tried that. Still doesn't work.

I did find what is causing the problem. It seems that altering the animation path is the culprit. At the top of the curve, the CVs fall inside the path, while the sides and bottom fall either on the path or outside the path. This difference in cv position seems to be the cause of the flipping. Anywhere the cv's cross to the inside of the path that's where the geometry flips inverse.

Any ideas?

SheepFactory

03-17-2003, 06:21 PM

Well I did it here on 3 different curves including a circle primitive like yours and it worked. I suggest you draw the curve again.

:shrug:

dmcgrath

03-17-2003, 07:59 PM

So I tried the thing, and I'll be damned if it's not doing the same thing to me as it is to dave_:hmm:

If I just have the one tread, and play it along the path it is okay. But as soon as I do the snapshot, half of them are inverted. I don't know what's happening yet, and I've never run into this problem before. Hopefully I'll figure it out and get back to you.

I have drawn the curve, three different ways, and even used a nurb circle, no dice.

I'll get back to this later.

SheepFactory

03-17-2003, 09:50 PM

Are you guys sure you are turning on follow on motion path options? and defining object up?

cause if you do it works.

dave_baer

03-17-2003, 10:15 PM

I've tried every setting almost every way. YES, follow is checked. As for Object Up... I can only change that in the attribute editor after I set the initial motion path. If I try to do it before I set the path it gives me an error for both Object Up and Object Rotation Up.

Here's the scene file if you want to play with it.TREAD (http://www.nuppi.com/Dave/tread.mb)

SheepFactory

03-17-2003, 10:37 PM

Thats weird man , I couldnt figure out whats wrong with your file , when I draw it it works but it flips on yours.

I think draw the curve again and try once more.

Ali

dmcgrath

03-18-2003, 12:54 AM

Yeah, Ali. Ive gone with just about every setting I can think of as well. It will play on the animation curve just fine. But when it comes to duping it in the snapshot, half of them flip out! Damn!

It's something I've never run across and can't fix right away, I'm getting a little pissed.

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