Need Help With Motion Paths

[TheWebExpert]

I am a rank beginner with Maya (started today).  I'm following a number of different tutorials to create the scene I want.

I have created a text that flows on a path.  Based on the tutorial, the text flows around the NURBS circle properly.

I have now created a second NURBS circle, with a second piece of text, also flowing around ITS circle.

However: The top text and bottom text are both rotating the same direction: counterclockwise.  I want the bottom text to rotate clockwise.  When the scene starts, there will be nothing.  Then, the two pieces will rotate in, from opposite directions, until coming to rest at the center.

How do I make the text rotate the opposite direction?  Thanks!

[Calebos · Accepted solution]

Hi. You have two possibilities. Principially you need to change direction of control vertices of the circle you are using as the Motion Path.

1st possibility: scale the circle in X or Z axis with value -1.

2nd possibility: in NURBS menu(hit f4 or select from the upper left pull down menu) and from the menu Edit Curves use Reverse Curve Direction.

[TheWebExpert]

Ok, the two pieces of text now start where they should and rotate in opposite directions.  However, when I created the animation, I set its time to be 300 frames.  That's not quite enough to bring the pieces of text back to the front a second time.  I've tried making the animation 450 frames in the space below the timeline, but that doesn't affect the animation; it still stops at 300.  I also tried recreating the motion paths once there were more frames... and the animation STILL stops in the same place!!

How do I make this happen...??!!  The text is going around a NURBS circle; I want it to start at point x (about 9 o'clock) and go around until point y (about 6 o'clock), one full revolution (from 9 to 9), and then one partial (from 9 to 6).  Help!!

[Calebos]

If I understand your problem well you need to play with U Value of each Motion Path. You created Motion Pathes with Start/End and Follow option? If not the lenght of the animation is taken from the timeline range. This is the first thing you have to look at.

The second one: if you want your text to spin around part of the circle, simply select the motion path and go to Graph Editor and there you can move keyframes so you can set U values for trajectory on the circle.

[TheWebExpert]

How do you edit the U value?  On graphs, I see nothing but a blank screen, even when selecting the NURBS circle and/or motion paths.

[TheWebExpert]

Ok, I have something on the graph screen.  I figured out how to drag the key to the end @ 450.  However, when I play back the animation, it is still starting & stopping at the same point.

If I edit the U value on the main screen (which for some reason is in red), it will move the text... but then again, the playback is still the same.

Ok, here it is again.  Here is my circle:

       12

   11     1

 10         2

9      *     3

  8         4

   7      5

       6

The animation on the top text starts at nine, goes all the way around to nine again, then stops at six.

The animation on the bottom text starts at three, goes all the way around to three again, then stops at six.

What I want to have it do is start at nine, go all the way around to nine again, go all the way around to nine AGAIN, and THEN stop at six.

(and the reverse for the bottom text).

How do I do this??

[Calebos]

Ok, so first your problem with length of the animation. Do you have set correctly the range of timeline? Because if you set the motion path range(just an example) to 100 frames even you have the animation length 200 frames, Maya will show you just 100 frames exactly form timeline range.

 Second: the motion paths works JUST with topology definition of the curve. In other words it starts from the first definition edit point and ends to last edit point. If you want to set the range of motion path as you want, use just rotation around Y axis of the CURVE which is driving your motion path. If I am not wrong your case is rotation of the curve around -90 degrees of Y axis.

 The reason: when you rotate the circle(curve) of motion path you are offseting the position/rotation of the object driven by motion path aswell.

 Simply: try to select the curve and rotate it around Y axis .. the text object will rotate the same ammount. 🙂

[TheWebExpert]

I'm really not understanding your explanation.   The timeline is set to 450.  The position markers say 300, but even when changed to 450, the animation starts at 1, ends at 450...  if I move the position marker, it still doesn't make the animation loop a second time.  I selected the circle and rotated IT, but that just changes the view of where the text is rotating; it is still rotating the same amount.

[Calebos · Accepted solution]

Yes. It is just for offset. If you want to rotate it more then 360 degrees you have to make it with roatatin Y as I wrote or you can rekeyframe it but it is a bit more difficult.

[TheWebExpert]

I rotated the circle on the Y axis; the text rotates with it.  However, when you play the animation, the text is still rotating the same amount.   How do I rotate or rekeyframe it as you said?  I have no idea.

[Calebos]

It is neccessary to change the animation curve for U value of motion path node. Each animation curve for motion path has two keyframes. First is the start one(U value=0 in some time, in most cases frame 1) and end one(U value=1, end frame, in your case 450?) For example: if you need your text object to make more then one spin around Y axis, lets say about one and half spin with 450 frames long, it means 360 + 180 = 540 degrees, you need to have first keyframe in frame 1(U value=0) the second keyframe in frame 300(450[whole animation frame length]/540[whole desired rotation in degrees]*360=300) for one 360 spin degree with U value=1, the third keyframe in approximately frame 300.5  with U value=0 again(how I wrote before: motion path is able to run just in U value range of NURBS curve, it means by default range between 0 and 1) and the fourth keyframe 450 with U value=0.5.

 All this is just for the example. You have to make it up yourself with actual needed timing and U values. It is very simple math.

For the motion path node is valid just U value between 0 and 1 by default(you can have the NURBS circle with U value between 0 and number of spans aswell but never mind that now) so if you want to make another "round" of rotation you have to start again from zero with motion path U value.

 For the detailed description check the user's manual ... there is everything really well described.

[TheWebExpert]

I have read your instructions and those with the program, and am still no closer to understanding.  In the graph editor, I was able to add a keyframe at position 450, and the animation went longer; I changed it to 750, and it went a bit longer.  But then things started getting weird - the animation started reversing direction.

I am really clueless on how to do this PROPERLY.

[Calebos · Accepted solution]

If you want send me your scene to josef.kasal@eallin.com and I will try to make it directly there with some descriptions. ZIP the scene if possible.

[TheWebExpert]

Thank you very much.  That is EXACTLY what I wanted.  I still don't know how to do it... but as long as it works, that's the main thing.  I'm still interested to find out how you made it do the effect.

[Calebos]

You are welcome. Check each motion path node of animated objects in the Graph editor. You will see the result clear. It is not so difficult. It needs some math to plan the movement.