In this lesson, we're going to go over the exercise that the previous video was about and if you haven't
completed it yet, definitely consider finishing that before you watch this or if you're having trouble
with it, go ahead and watch this one and hopefully it'll help you out as well.
But I think a lot of the animation in general is, you know, you don't really internalize these concepts
until you try them yourselves.
So give it a try.
You're not going to get a perfect I this exercise with you and I, you know, enjoyed it.
It's always nice to refresh these concepts, even as someone who's been animating professionally for
eight years on big, you know, feature films, this kind of stuff still is helpful for for me.
So definitely take a moment and give it a try.
So let's take a look at what I did.
And you can open up the scene, file the ball, exercise, end and open up this exact scene file to
see what I made.
So lets it play.
And we can already tell, you know, right away that each ball has a different type of weight.
And let's discuss what is actually contributing to that difference.
So if we take a look at the beach ball, it you know, it takes longer to fall.
So, you know, we don't live in a vacuum.
If if we lived in a vacuum, then these would both fall at the same rate.
But because this ball is bigger and it has more drag with through the air, it's going to take longer
for it to get to the ground.
But this ball is smaller and it's heavier.
So it's going to fall just a few frames quicker.
We can see if we step through that, there's maybe three frames or so one, two, three, maybe four
frames difference between when they come off and when they contact.
That might be exaggerated a little bit.
Of course, what I did isn't perfect either, but you kind of get the idea and the concepts behind this.
Also, we can see that there's way more bounces on the beach ball, whereas the bowling ball just bounces
twice, basically very shallow, very short bounces because it's so heavy, it's not going to bounce
a lot.
And then the other thing we can look at is the bowling ball continues to roll.
It's a heavier object.
So it takes a lot more friction with the floor to get it to stop.
Whereas with the beach ball, it's very light.
And so any little amount of friction with the floor is going to kind of slow it down a little bit.
So let's take a look at the scene file and dig a little deeper here, because it also kind of left you
to the wolves with the rotation stuff.
So we'll discuss all that.
So let's go into the scene file and basically how I approach this was I didn't think about the rotations
at all, OK?
I had all of these setups so that their rotation axes were all straight.
So that would be easy to rotate.
Right.
If we take a look at the attributes over here and we rotate, it's only changing one value.
So what I did was I animated the translation just like we did in the first generic ball that I walked
you through all that stuff I did all of that same thing.
And then when I was done with all the bounces and all of this stuff, I went back in and I set two key
frames and I animated the rotation.
So basically what I did was in the graph editor, let me just duplicate this out and show you I'm going
to save this real quick and my duplicate this bowling ball and drag it over here and kind of show you
what I did.
So it's on the ground and we'll set a key here and then we'll set a key over here and say it travels
this this far.
And so right now, it's just sliding across the floor.
Let me just hide these two so we're not distracted by them right now.
I'm gonna delete the key frame there, right.
Clicking And then I'm going to turn that off.
So they're hidden.
So we basically have this is just sliding across the floor.
But if we take and isolate this rotation, so it's going to be rotate Z and I can see that down here.
And let's make both of these linear so it's easy on us.
And now we can basically scrub through and take this last keyframe a hit w so have the manipulator and
I'm going to hold down shift in middle mouse, drag this down.
You can see the balls rotating.
So I'm going to move it down a little bit and then just scrub the timeline it just visually check it
and see it's still sliding.
Someone to move.
I'm going to move the keyframe down more so it'll rotate even more and then scrub it and check it.
Now it's rotating too much, so I'll bring the keyframe back up.
And then right now it looks like we're pretty close to that Goldilocks moment.
Might be sliding a little much there.
There is math, of course, we can do based on the radius of the object.
But for most things and just the general idea of how to quickly get this stuff in, this is a pretty
good way to go about it.
Still looks like it's sliding or still.
Yeah.
So somewhere in here basically is what it looks like.
And this is just take some, you know, back and forth and training your eye to kind of see what that
rotation is like.
The the beach ball is actually probably a little easier example to show that with so much going to bring
those back from the outliner because I hid them, I can't select them to unhide them so I could open
up the outliner from the window menu.
And now I can type in a one to turn that on and I'll just turn the outliner off there.
So the other thing that I want to talk about was how I slowed these things down, because they're going
at a consistent rate and then they they both kind of slow down and especially with the rotation set.
How do we do that?
So basically, I took a keyframe at the when we had the infinity turned on and then I just dragged it
out.
So it slowed it down.
So basically was a straight line here.
You know, this key frame was not an auto tangent.
It was, you know, a straight line just like the other ones.
So, you know, it'd be like going over here and setting a key frame in this infinity space here.
So I just had s so I made a new key frame because auto tangent was the default that's going to go flat.
And that's fine because I'm trying to slow the ball down.
So now I can just middle mouse drag holding down shift and pull this out.
And that's how I slowed it down.
But I made sure to do both the rotation and the translation together so that the rotation slows down
an equal amount relative to the translation.
So that's how I did that.
And then the last thing I wanted to show you was a little kind of overshoot thing with the beachball
that we haven't done yet.
So it slows down and then just comes to a complete stop here, which is not very believable.
So what we can do and let me just go in here and clean up these.
Yeah, these are old keyframes or at least just get them all lined up on the same key so we don't have
stray keys out here.
So what I can do and one really cool feature I use pretty much every day, almost every hour of every
day when I'm animating is choosing a place in the timeline.
And for me it's going to be a place I want the I want the ball to roll backward.
But we need to put a key frame out here, you know, because I'm going to play in time and we need a
place over here to key back to have it roll back so I can just pick somewhere that I already have the
rotation values already set.
And I know if I were to bring it over here, it's going to work.
I could set a key copy paste it.
But there's one tool here that if we just middle mouse drag from some point in the timeline, you can
see nothing's moving now because I have my middle mouse dragged down so I can move this kind of value
in time here to wherever I want it to and let go.
And it s and so now when we scrub, it's going to take that key frame and bring it back and put it wherever
I let go and then hit s.
So it looks like I think I need a little more distance here, so I'm going to grab one, do like frame
five and drag it a little further out and it.
S so now when I scrub it rolls backward.
So that's kind of like a little trick to get like a free keyframe, especially when you're dealing with
rotations.
And I don't want to like, try to figure out the rotation again.
Well, I've already figured it out in this section so I can just take advantage of that and M. M. section
like a frame over here and just put it over here and let go and hit s.
So with that, we are done with this ball exercise and I definitely encourage you to do this again and,
you know, go back and watch this and really understand these concepts and get them in your and your
mind about how to think about animation.
Right.
Because we're animating specific things every time we animate.
You know, no.
Two things are going to ever move quite the same.
So you want to try to think about the properties.
How heavy is this thing?
You know, how what's the surface like?
Is it a.
Rough surfaces that have more friction, is it you know, can is a very elastic it's going to bounce
a lot, all these things we need to take into consideration when we're animating, because that's going
to affect the type of animation we're going to do on, you know, with all of these principles now that
we understand with squash and stretch and timing and spacing and all of these types of things.
So things we're watching this little section.
And in the next one, we're going to do a little more complex animation.
Thanks for watching.