Let's Roll

Here's a basic overview of the graph editor tips I went over today. I applied this to a simple ball bounce so you guys can see more clearly how it applies to ease-in and ease-out, and how tangents can be edited together to produce smoother motions. Following this advice will help you guys to start using good Graph Editor habits and getting the most out of the curves you create.


Start by creating a curve on RotateX (RX) and TranslateZ (TZ).



It doesn't matter what order you do this in, just make sure each channel has two keys over a span of the exact same time.



So for example, if you make your keys in RX on frames 1 and 40, put your keys on TZ on 1 and 40 as well.




Make sure your curves are set for weighted tangents. You can also set this to be default for your curves in the Animation Preferences box. (Bottom right corner of Maya)



Now set Free Tangent Weight on the tangents (make sure they are selected) so you can pull the tangents out and set the ease-in and out manually.



And finally break tangents. Remember, you can hotkey all these steps. I have mine set like this:

J-free tangent weight
M-break tangents

and my tangents are set as weighted by default.

Now edit the values of the TZ and RX so your ball looks like it's rolling. You can grab the keys in the Graph Editor and move them up and down, depending on how much you want your ball to move. You set the rotation to look right by eye, but make sure you playblast every once in a while to see if it's right. Too much or too little rotation will make the ball look like it's sliding. Make sure you get a nice roll:



IMPORTANT: Adjust the ease-ins and outs by pulling your now free and broken tangents out, but make sure that you move the tangents for the RX and TZ AT THE SAME TIME!
If you move them separately, you'll have a really hard time making the ball roll look smooth.



Now at your Translate Y (TY) onto your ball for the bounce. This is summed up really well in Bobby's video so I'm going to kind of skim over it.

Tip: You can add keyframes into a curve by holding donw "i" and hitting the middle mouse button into the area of the curve you want the key to go.



Change the tangents at the lowest values (when the ball hits the ground) to linear so you get the feeling that the ball is bouncing sharply and not easing into or out of the contact frame.



Next, set the tangents on the apex of the arc (at the balls highest point in the bounce) to free tangents. Move them out accordingly to get some nice, exaggerated air-time on your bounce.

When you pull these tangents out, you'll notice that the curves at the bottom by the bounce will start to "bow" and bend in a way that you don't want.
Change those tangents to free and broken and move them so they're nice and smooth coming into and out of the bounce. Avoid this:



and be sure they look smooth, like this:



Experiment with tangents to see what different effect they have on your animation.

Always be careful when moving a tangent and make sure you're not messing up anything else down the line.