3 Replies Latest reply on Oct 23, 2009 2:53 PM by Tony Heagren

motion problem

HI all,

quite new to CS4 and wondering how to make a simple ball follow an oval motion path ?

Think of a molecule spinning (and looping) around a nucleus.

This was five seconds work in previous versions where you could draw the motion guide then

simply attach an object to it and say "orient to path"  but I can't seem to find how to do it in CS4.

I'm sure it's easy - I just can't find it !

All and any help[ much appreciated.

• 1. Re: motion problem

Greetings Tony,

Actually, in Flash CS4, you can choose to use the classic method, or the new method.  Both have their own set of advantages and I often use a combination depending on the type of animation I want to perform.

When using the new Motion tween method of animation, there is often one thing that throws people off:

When you set a keyframe by moving, scaling, rotating, or changing an attribute, only that attribute is set as a keyframe.  All other attributes are not keyframed unless you set them also on that same frame.  If you bear with me, I'll try to explain what I mean.  Let's say you have five key frames.  The first has the alpha of the object set to zero.  The second has the alpha set to 100.  The third has the object Rotate 90 degrees.  The fourth Rotates the object -90 degrees.  The fifth sets the Alpha to zero.

Under the classical tween method, the object would first fade in, then rotate 90 degrees, then rotate -90 degrees, the fade out.

With the new method, you would have the object fading in and begin rotating while fading in.  As soon as it is done fading in, it would continue rotating, but it would immediately start fading out and continue fading out while rotating 90 degrees and back -90 degrees until it reached the last keyframe.

This is because a keyframe isn't a keyframe for every attribute, but for individual attributes.

In order for it to work the way you would expect, under the classical tween method, you would have to set additional keyframes on the same frame of other keyframes.  So, if you want the fade out to begin after the -90 rotation is complete, then you would need to set a keyframe on top of that keyframe that has the Alpha at 100.  Basically you want flash to start at alpha 0, then go to alpha 100 then stay at alpha 100 until the -90 rotation is complete and finally fade out.  If you decide to add a position keyframe in the middle of this fade-in, fade-out animation, it won't affect the alpha animation since the movement of the object is controlled by a different set of keyframes.

The next thing to understand is that the position keyframe automatically creates a motion guide.  And, you can use the selection to to bend the motion guide, and/or use the direct select tool to adjust handles of the curved guide.

Those are the main concepts to understand.  It's also a good idea to learn about the "Motion Editor" as well.

So, to build the animation you want, first create an oval on the stage (just an outline which will be used as a reference), Create your ball Movie clip.

Place your Ball Movieclip on it's own layer and place it in the starting position.

Right-click the layer with the ball movieclip and select Create Motion Tween.

Extend the timeline if needed.

Halfway from start to finish, select the frame and move the ball to the opposite side of the circle.  (Maybe scale the ball down smaller to give it a 3D look when animating).  Now go to the first quarter frame and move the ball to where it should be at that moment.  And go to the third quarter frame and move the ball to where it should be at that moment.  Finally, go to the last frame and move the ball to the start position and scale it back to it's original size.  Now use the selection tool to curve out the motion guide so that it matches your reference oval.  And use the direct select tool to adjust any handles that aren't curving correctly.

And there you have it, you should have a nice loopable animation of a ball following an oval.  You can delete your reference oval if you choose.

Good luck!

• 2. Re: motion problem

A very good explanation!

Just another trick to save a number of steps. Instead of using a reference oval and shaping the motion path/moving the object around:  take that oval, erase a tiny hole out of it where you want the animation to start/finish (so it's not a closed path), and copy-paste it onto the motion.

For a migration guide on updating to the new model:http://www.adobe.com/devnet/flash/articles/motion_migration_guide.html