- [Pierre] In this video, we will start animating the feet
based on the root of the torso motion.
The first thing to do
is to double the length of the motion we just created.
And we need to repeat this up and down cycle.
With all my curve controllers selected,
I will duplicate them.
But first, make sure that the very first controller
and the very last are exactly the same.
Then press Shift + D to duplicate
and offset by the length of your animation.
In my case, 36 frames.
So that my whole cycle run through 72 frames.
Again, this is the rhythm I have chosen for this animation.
Your animation can be faster or slower.
From there, I will press Alt + H to un-hide my controller,
select the visibility property bone
and they will re-enable the legs.
Since the legs are using an inverse kinematic mechanism,
we will just have to animate the foot controller.
The cool thing with this animation method
is that it's easy to tweak the position of any controller
by slightly offsetting the curves.
If I want to raise the up and down motion of the character,
I just need to select the root controller
and offset the whole curve
on the y-axis in the graph editor.
The up and down motion will occur higher,
giving more space for the foot motion.
But it doesn't matter, even if it doesn't look good
I will be able to get back onto this curve
and offset it at will.
The first thing to do from there
is to position our feet based on the motion of the torso.
Generally, the up pose,
the moment where the torso is at its highest point
is close to the passing pose.
It is generally slightly delayed.
When the foot contacts the ground, the torso goes down.
And when the foot is pulling back, the torso is raising.
Since the torso is almost at its highest point on frame 20,
I will slightly move the foot back on this frame.
And on frame zero,
whenever the torso is at its lowest point,
I will push the foot forward.
The idea is not to get 100% accurate
but just create a few landmark
before we use the curve and adjust the rhythm.
Finally, the foot will be third or away on the back
whenever we have just hit the down pose.
And then when the character is pushing on the other leg,
the current foot will be raising.
The idea here is to work only on one axis
as we did for the torso,
setting the position of the foot
just before it leaves the ground.
Finally, I need to find the moment
where this foot will get back forward,
and this should have happen just before the body is falling.
The foot contact the ground
and then we have the down pose of the torso.
Our animation doesn't look pretty at all
but at least we have the main landmarks.
Since the forward motion of the foot will be mostly linear,
I will select all the key frames of the foot,
press V and change the handle type to vector.
As we did before with our squirrel character,
we will consider the cycle to be linear,
meaning that the character is moving at a constant speed.
Hence, I can remove the key frame prior to key 33,
because we just need to key frame,
one starting point and one and point
to create this linear motion.
Let's switch to the graph editor.
To get the right pace of the foot when on the ground,
I need to interpolate from frame 60 back to frame 33
through the whole cycle.
Because frame 59 or 60 mark the moment
our character is contacting with the ground,
while frame 33 is the moment the foot is leaving the ground.
So this plateau is not correct
nor the interpolation between frame zero and frame 33.
But what I can do or what I should do,
because I've made a slight mistake,
is to duplicate the key from frame 34 on frame 105,
which stand for frame 72, the end of the cycle,
plus frame 33.
This way, between frame 60 and frame 105,
I have the whole motion of the foot sticking to the ground
with the right interpolation.
From there, I can go on frame 72, the end of the cycle,
and insert a key frame on this channel.
I can now duplicate to this key frame
and move it on frame zero
and set both to free or to vector.
Now, both the first and last key frame are the same
and they have the right interpolation
and the foot is moving at the right speed on the ground.
Now I just need to work on the up and down motion
between frame 33 and frame 60.
We can also adjust the moment
the foot is leaving the ground,
I think it could happen a little later.
Now that we know how to fix the interpolation
between the beginning and the end of the motion,
that's perfectly fine.
The other thing to consider
is that while the foot has linear or motion on the ground,
it won't have linear motion in the air.
By rotating this handle,
I will create a slight overshoot backward
as if the foot was projected the backward
because of its inertia when leaving the ground.
With this row editing done,
I will switch to the Z location curve
and they will simply add a new key frame
between the landing pose, between the contacting pose
and the pose where the foot is leaving the ground.
As usual, you can see here the final curve
for both the Y and Z axis.
As I did for the torso, to get a satisfying sense of weight,
I will make a slight plateau or moving halt
just before the foot hit the ground,
so that it will have some kind of a hard time to raise.
It will stay up before landing very quickly
because it's very heavy
and the robot is kind of releasing the foot.
So it creates some kind of nice contrast on the curve
that currently translates on the animation.
The tricky thing about this method
is to focus on one motion at a time.
And here, you may find out the motion looks a bit weird
because there is no rotation in the foot.
But we will input some rotation in the foot
slightly later on.
Just focus on one channel at a time,
one controller at a time.
And even focus on the motion of the controller itself.
Not necessarily the motion of the whole robot.
As any other animation technique,
it will take you a bit of time to get used to it
but it's very handy for this kind of animation.
Before we call the base motion of the foot down,
I want to slightly push forward the foot
just before it lands.
To do so, I've slightly rotated the handle
just before the contacting pose,
so that the foot gets a little more forward
before it hits the ground.
From there, I can adjust the up motion of the foot.
Don't hesitate to track the arcs of your animation
using the motion path we have seen in the previous chapter.
In the next video,
we will use the foot roll controller
to add a bit of rotation on the ankle and on the whole foot.