Original subtitles

- [Instructor] Regarding the bag, more than polishing stage,

it's going to be an animation stage.

While the blocking did help to get an idea

of what we were going to do

and what would be the behavior

of the bag during the animation,

since the main controller animation

or motion is pretty simple,

it's almost easier to work directly in the graph editor

for this kind of motion.

And then we will rework the different tweaker bones

or even erase all the key frames and rebuild their motion.

Since the bag has a pendulum motion

with an extreme low and an extreme high,

it's useless to have more than three key frames.

One for the beginning, one for the extreme,

and one for the return.

So at this stage, I'm getting rid

of any useless key frames I did during the blocking stage.

From there, I can start working on the X rotation axis,

which is the main rotation axis of our bag in the beginning.

In the beginning, it's pretty close

to what we were doing with the character.

I have two contact frames with the fist.

After the first punch, the bag starts to move a bit.

Then, during the second punch,

I'm keeping the bag a bit backward to make sure

that the fist penetrates the bag.

Don't over-focus on this part though

because this is something I'm going to change later on.

But this gives me the starting point

for the first pendulum motion of the bag.

And once you have that, you just need your starting point

and where the bag will end before the next punch.

And we just need one key in between,

so I will get rid of everything but those two keys.

Then, we just need to convert the start and end key

to vector, and then work on the scaling

of the handles of the extreme key

exactly as we will do with the up and down motion

of a bouncing ball.

From there, you need to watch several times your motion.

See if it feels right, and then edit any of your keys.

Maybe scale a bit up or down some of the handles

to accelerate or decelerate the bag

whenever it's going down or up.

Here, you can see the final shape of my X rotation curve

on the first bounce.

Regarding the X and Y rotation curve,

during the first swing, there is not that too much to do

than getting rid of any keys that could be in between.

And set the handles of the starting and ending keys

to vector so that we have no interpolation.

I haven't done it on the Y rotation.

That's a mistake, but it's not even noticeable

in the animation.

On there, I need to redefine the moment

where the bag will start to move.

It's currently one frame earlier that what I have right now,

and since I want to hold the pose

for the first impact of the hook,

I will simply duplicate the keys from 45 onto frame 47.

This will create a plateau

where the bag is no longer moving,

and I can get rid of the keys after this one.

Here, we've just defined the starting point

of the pendulum motion of the bag after the hook.

Now, I will go on the next contact frame on frame 78,

and I will refine the position of the bag

so that it perfectly matches the shin of the character.

I've now defined the starting point

and the end point of this next pendulum motion.

So, I can get rid of all the key frames in between

and rework its motion.

From there, I will rebuild some kind

of the same curve we had with the bouncing ball

or the previous pendulum motion.

I will select the Z rotation rotation curve

that is going to be the main rotation channel

for this specific bounce.

I will duplicate the key.

I put it right in the middle and switch it to auto clamp.

Then, I will make sure that the starting

and ending keys are set to vector.

From there, I have my base motion for the second bounce.

From there, I definitely need some more love.

I will refine the position of the hitting frame.

From there, I will bring a little more contrast

into the shape of the Z curve

as you can see on the reference.

This way, the bag will be pushed faster

and will come back faster, which will look more impactful.

And from there, I've worked a bit on the X rotation curve

so that the motion of the bag was currently

physically correct because in its current state,

the bag has a weird motion from frame 60,

where it starts to rotate to the left

while there is absolutely no force

that would generate this rotation.

So just after the punch,

I will put a bit of a right rotation,

and then the bag will swing back to the left.

Polishing the motion of the bag

just after the kick was a bit closer

to what we did during the polishing of the character.

As I'm making the bag holding a bit

onto the character's shin,

and then it starts to swing very fast.

Once the bag is projected after frame 80 'til frame 85

where it gets out of the camera range,

its motion is pretty close to what we already had

with initial keys set to vector

and then a big acceleration.

From there, since I want the bag to land flat on the ground,

I just got rid of all the keys on the X and Y rotation axis.

Then, start working on the root controller

of the punching bag.

And again, here it is gonna be super simple compared

to what we have done before.

So, the first thing is that I can get rid

of all the key frames before the root starts to move.

Then, I will get rid of any key frames

between the starting and landing pose.

Then, I will have refine the location of the bag

once it hits the ground based on the camera frame.

And from there, I will convert all the keys

to vector because why?

Well, one, there won't be any change in the speed

of the bag on your recent channel.

So on the X and Y location channels

exactly as for the bouncing ball.

A few frames after the hit,

I will slightly offset the value of the Y location curve

so that it feels like the bag is sliding a bit

on the ground.

I've done the same with the X location curve,

and I will convert both keys to auto clamped.

Then, I just need to scale those two keys

to create a heavy feeling as the friction of the bag

on the ground slowing down.

Now, the only curve that needs

to be worked on is the Z location curve,

and as you can see, it's going to be super simple.

Now, the only thing I'd like to improve is

as for the character, the silhouette of the bag.

As it currently lands on the ground,

we just see the top part of the bag.

And if we were only keeping this still frame,

we wouldn't be able to identify a punching bag.

So, basically this is a bad pose.

First thing I will do is use the master rotation controller

to make sure that the bag is flat on the ground.

From there, we get back onto the root controller

of the bag, and I will use its Z rotation axis

to rotate it a bit to the side.

Since the bag is airborne, its rotation will be linear.

And then just after the impact,

I've pushed a little bit the rotation further,

and I've made it ease.

This is to simulate the friction of the bag on the ground

and the fact that it's slowing down.

The bag is rapidly stabilizing on the ground,

and I haven't added any bounce so that it feels very heavy.