TANK TREADS?

[Kelley]

I'm doing a pretty easy 'rolling stock' animation: just simple turning wheels and tank treads. About those treads...I've got a few ideas on how to go about it, but they draw on my old polygon days. I'm wondering that, if I install a bone in each tread plate, and make each bone the child of the one before it 'til I arrive at the last, will the 29 children smoothly follow the 1st parent?

[totlover]

i dont know the answer to the question but i like the tank

[Tunames]

There's a tutorial somewhere for that very thing. Check the A.R.M.

[KenH]

You could make a (nearly) circular path and constrain the bones to it.

[Dhar]

I'm just glad to see you still pluggin' away at this project, Kelley

[Kelley]

You could make a (nearly) circular path and constrain the bones to it.

 

Hi Ken. Good to hear from you again. Indeed, I could make a path and constrain each tread plate to it. The problem is, there are twenty four tread plates and twenty four positions each plate must move to. To get one full revolution for the tread as a whole, I've got 24x24 operations. I did this once in Carrara with a 30-plate tread. 900 operations is a lot.

 

I wince at this possibility because I find the constraints in A:M to be very squirrely. I have six vehicles on the bridge. each has a Rim Light 'translated to', and put into a Light List. Every time I open the project to work on it, I can be sure that at least two of the 'translate to's have dissapeared, and two or more Light Lists will have to be re-established. To have to check the constraints on 24 plates per tread X 2 treads per vehicle X 6 vehicles, every time I'm ready to render a scene would put me over the edge. Hence I hoped I could make a twenty-four bone chain.

 

I'll check out the other suggestions made here, [thank-you all] but my first fall-back solution was to delete all but one tread plate, and [in Bone's Mode] move it through its 24 positions, make an Action, then move the scrubber to Frame_2, add a tread plate and drop the action on it, repeat at Frame_3, and so on...

 

By the by, I got the wrong pic. in my first posting. Here's the vehicles as of today.

[KenH]

You always get strange problems. Nice tanks you got there.

[Kelley]

You always get strange problems.

 

Yeah. Tell me about it.

[Kelley]

I think I started this thread saying something about, "pretty easy"..."just a few turning wheels and treads".

 

The first tread [right hand] went well. moving each tread plate through 24 positions, and making an action of it. As I was about to do the same thing on the left-hand tread, I twigged to the idea of just selecting the bone and control points on the right tread, and then adding in the CP's for the left. One bone for both plates, both treads. And it almost worked.

 

When I did a one cycle, 24 frame animation, I see that several of the left-hand plates leap to the far right side of the right-hand tread, starting at Frame 9. But even though both left and right are controlled by the same bone, the right-hand plates don't move. How can this be?

[largento]

I have absolutely no idea if this would work, but I wonder if you could get away with a loop that just moved everything from the current position to one position over...

 

Like on a gear... if you you can do just enough movement to get one sprocket to move to the position of the next sprocket, in a loop, it looks like the whole gear is completely revolving...

 

Like I said, I have no idea if this would work, but if it did... :-)

[MMZ_TimeLord]

Here is the link to the old tank tread tutorial article found on A.R.M.

 

Cheers!

[Kelley]

Here is the link to the old tank tread tutorial article found on A.R.M.

 

Thanks much! I had looked for this on A.R.M. and didn't find it. I printed it out and will duly soak my head in it tonight. Looks like there's a lot of stuff in there worth knowing.

 

But in the meantime, I've got this tread that's almost there. except that the CP's are jumping around on one side and the bone, and other CP's aren't.

[Dhar]

Have the CP's channel editors in question their interpolation been set to zero slope?

 

I have had a problem of 'wandering CPs' when my model was built in v12 then trnasferred to v13. But your screencap shows a more extreme case.

[Kelley]

Have the CP's channel editors in question their interpolation been set to zero slope?

 

 

I opened the Channels in the Bones folder. The interpolations default, as far as I can see, is set to 'Spline' throughout. I changed several to Zero-Slope, but it doesn't seem to change the tread jumping. Also, I'm wondering if those gaps in the interpolation timeline should be there.

 

Thanks for the help. This is 'terra incognita' to me.

[Kelley]

SOLVED IT!

 

The bones [and pivot points] are all in the right-hand tread. Somehow the bone on several tread plates got rotated 180 on the Z-axis [running front to back]. That flipped the left-hand tread CP's over to the far right side of the tank. I suddenly noticed that the distance was approx. equal whether the tread plate was to the right or left of the bones.

 

Why they flipped is still a question. Only the bones on Tread Plates 9 through 14 were a problem. [out of 24].

 

I was told, some while ago, that objects set to 0, 90, and 180 degrees sometimes flip to the reciprocal. I was advised that it is sometimes better to place an object at 179.9, than to put it at 180, which can default to 0. In my case, that's the difference between left and right, or, having the tread plate face up or down.

[serg2]

Old method for tank treds - distortion box in attach file

tank_treads.prj

[Kelley]

Old method for tank treds - distortion box in attach file

 

Thanks serq2. I opened the file...and while I've never used a distortion field [in A:M I still need BOTH hands to find my butt, despite what it says under my avatar]...I'm assuming that the field flattens the circular treads? I did a test rendering [24 frame] and the treads stay circular.

 

In any event, it's a clever solution to treads. I have resolved that my next tank will have a generous amount of side armor with tread only showing at ground level.

[serg2]

press key "Space" - redraw

[Kelley]

press key "Space" - redraw

 

When do I press the 'space' bar? At the beginning of the rendering?

[serg2]

When you open action FlattenBelt

[Kelley]

When you open action FlattenBelt

 

Aha! Thanks. I'll give it a shot!