Help: Expressions and Joes Rigging Tutorial

#1

I’m going through Rigging 1.

Things are OK until I get to the expressions section.

He has you select a foot bone called Arch, which runs from the ball of the foot BACKWARDS to the heel.

You create an expression for this bone’s heading.

Then he selects the Toe – which is a bone running from the ball of the foot to the toe. You add this bone’s heading to the channel.

According to Joe – and accordning to what happens in HIS Messiah, this will mean that any time the heading of the arch is moved, the heading of the toe will match.

EXCEPT… the heading is different for each bone. Since one runs to the back of the foot, and one runs to the front of the foot, they are heading in opposite directions. So, when I say: “The Toe’s heading = the arch’s heading” Messiah flips the toe bone around to point the VERY SAME way as the arch bone – causing my foot to be twisted.

That actually makes sense to me… except that’s not what happens to Joe! His toe simply mimics the arch, but stays pointing out.

For the life of me, I can’t figure out why! Is it because I am in Messiah 3?

The thing is, the arch bone is created by adding a bone from the toe, and then using pitch to flip it 180 degrees. When this happens, the headings are, necessarily, opposite. So, I think my bones are set up the very same way his are… and yet my results are completely opposite.

Anyone have any idea why?

(BTW, a work-around is, of course, to change the expression. I find that if I say that the toe = the arch heading +179, it behaves the same as Joes… I am puzzled though as to why his Messiah acts differently than mine…)

Joes:

Mine:

#2

This issue came up a few times here in the forum, just have a look for them. Most probably the difference between your rig and Joes’s is that he had built it with the head of the character facing away from the camera instead of looking to the camera.

#3

I will look around for other threads… and I tried to match the mesh by rotating it, but you may be right.

Still I don’t understand why that would matter… The problem isn’t the mesh… it is the bones behave differently for me… whether the toe faces south, or the arch faces south, I would have to think that the same problem would occur since they did not both face the same way…

I’ll look around on the forum and see if someone else figured it out. Thanks!

#4

Interesting read… It took some plowing around, but I think I found the thread you were referring to…

What was interesting was that [color=white]lmilton[/color]- programmer at PMG – posted this as the solution

Secondly, the expression was wrong in Alex’s scene. In the reverse foot portion, he was applying the heading of the arch directly to the heading of the toe bone:

±+var
| |_[K_ArchR:heading
|_K_ToeR::heading

That would most certainly cause things to go haywire. It should have actually been:

±+var
| |_[K_ArchR:heading]+(DTOR*180)
|_K_ToeR::heading

… to rotate the toe in the opposite direction 180°. As an added “feature”, setting the channel operator to + will allow for additional control since the toe bone could still be rotated, as needed.

Which is similar to the hack I used – except he applied DTOR (and I am not sure what that is…)
The question still remains, tho… why did it work for Joe without doing that??? It must have something to do with the foot rotation he uses to get the arch into place. I will have to go back and slow-mo the video and see if I can see what he does differently. It can’t be a straight pitch…

#5

Joe knows messiah voodoo magic.
Oh, and DTOR is Degrees to radians. you use it to easily figure out the radians of a degree of rotation so you don’t need to punch in rotation numbers in radians.

#6

I am beginning to believe it!

And it works great… the expressions work perfectly on my foot now.

Next question:

WHen Joe clicks on a bone and the pitch controller… then clicks into the Channels section, that bone and channel is now the default for his selector… so all he has to do is hit the ‘+’ key to insert it into the expressions.

WHen I click on the bone and pitch… nothing happens. I still have to select the bone from a drop down list. Any idea why? (I am in MS3… Joe is using MS2… but that should still work…right?)

#7

Just activate the checkbox right next to the ‘+’ button.

#8

Wow… subtle… (I didn’t even know that was a check box!)

Thanks!

#9

FWIW… I was checking out this issue again, just because I hate not understanding why things happen… Anyway, this time, I loaded up the file Joe ships with his CD.

There was his foot… with the heading set exactly the way he did it in the video.

Amazing… The way I would have sworn IT WOULD NOT WORK… there it was… toe heading = arch heading… and toe pointing forward…

Just for grins and giggles, I grabbed the HEADING of the Edit Sphere to move it and see if the toe would follow the arch. Mind you, I had not changed anything. This was Joe’s file that he ships with his CD. The second my mouse clicked on the edit sphere - POW! the toe spun around 180 degrees – exactly like it did when I was trying this with my rig!

I put the + (DTOR * 180) in the expression, and the toes snapped right back around – just like here.

So there must be some magical setting Joe had on his Messiah 2.4 studio… but the mojo does not travel with the file…

#10

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