- [Instructor] As we've seen subdivision surface modeling
is a method of using limited control points
to produce highly curved or smooth flowing surfaces.
We can achieve similar results on raw polygon meshes
using a feature called soft selection.
That gives us a region of influence
around selected sub objects.
We can actually combine soft selection
with subdivision surface modeling
to get an even higher level of control.
We've got a version of the task chair seat cushion here.
Let's activate the modeling ribbon,
if it's not already visible.
Click show ribbon.
And we want to be in modify mode
with that object selected click on the modify mode button.
And we're now at the level of the open sub div modifier.
We need to be at the level of the editable poly.
Go down the stack by clicking previous modifier
a couple of times until we see the words
editable poly displayed in the ribbon.
I've also got show end result turned off currently.
We could enable it here if we wanted
but I actually want to have it turned off
in this case just temporarily.
I want to be able to see inside the model.
Let's go into a sub object mode,
choose vertex sub object.
And if we select a point and grab the move tool
we can position that point in the usual way.
We're all only affecting that one point.
I'll undo that with control Z.
Turn on soft selection and we'll have a region
of influence around that point.
We can enable soft selection from the modeling ribbon.
Click on this button over here
that looks like a bunch of colorful circles
and that will launch up a separate floating window
for the soft selection controls.
We see that the vertices on the model
have all changed color, and this is a sort of heat map.
Warmer colors or colors closer to red
will be influenced more when we manipulate
the hard selected sub object,
which is highlighted in red in the usual way.
If I click off the object,
all the vertices are displayed as blue,
meaning they're not selected in any way.
If I select a vertex such as this one,
it's highlighted in red and everything else
changes colored to indicate how much it's been selected.
To control how much those vertices are selected
we'll adjust the fall off amount,
which is the influence around the selected sub objects.
We can adjust the parameters either in the modified panel
or in this little floating window.
If we scroll down in the modified panel
there's a soft selection rollout.
We might need to open that up.
And within there we've got parameters such as fall off.
I can click and drag on that
and reduce the amount of fall off.
If we bring that down to something like 20 centimeters
and we see we have a much smaller area of influence.
If we click and drag, for example, in the Z axis to move
we see that even though we've only got one vertex selected
we're affecting all the nearby vertices.
I'll undo that with control Z.
Also notice that as we change the fall off distance
the move gizmo shifts around on the model,
and that's kind of an annoyance.
It's moving to the average position
of all of the soft selected sub objects.
It would be better if the transformed gizmo
would stick to the hard selected sub objects
but apparently that's not an option at the current time.
We can also change the fall all off and other parameters
from the floating window that was launched by the ribbon.
To change the fall off interactively,
we can click on the little pencil icon,
that's edit mode and we get a cursor that looks like
concentric circles that will allow us to
adjust the fall off radius.
Just click and drag and move your cursor up and down
in the view port to increase or decrease the fall off radius
and then switch back to the move tool
and perform our transform.
Okay, I'll undo that.
Going back to the edit tool, selecting that,
if we click out here in an empty area of the view port
just click on nothing, then the cursor to changes
and now we're not adjusting the fall off anymore.
We're adjusting another parameter, which is pinch,
and that's going to affect the linearity of the selection.
So if we click and drag, we'll increase
the amount of pinch if we drag upward.
And we can see there's actually a graph over here
in the modify panel giving us a preview
of what that selection's going to look like.
It's like if I give this an extreme pinch amount
of let's say one or so,
go back to the move tool and click and drag,
move up in the Z axis, we can see the end result
that we've got that pinch effect.
So we've altered the linearity of selection
as mapped onto distance.
Okay, I'll undo that with control Z.
And then back to the edit tool once again.
When we first initiate it we're adjusting the fall off
click once to adjust the pinch
click a second time to adjust bubble, and click and drag
to increase or decrease the bubble amount.
And we can see the result once again, if we position.
So we've got a high pinch
and let's increase the bubble here
actually in the modified panel,
and we can see that we're able to get these sort
of complex selections of soft selected vertices.
Okay, I'll undo all of that control Z
a whole bunch of times.
Take me back to where I was.
And we can set the pinch bubble numerically
from this floating window as well.
To do that, you'll need to click on
the right facing arrow over here.
There's a button that says soft, click on that.
And then we have access to all these controls.
So I can, for example, set the fall off
to maybe seven centimeters press tab and set,
pinch to zero, press tab and set bubble to zero also.
Okay, so that's how we can adjust those parameters.
Let's reselect this vertex in the center of the cushion
and with the move tool, active click and drag up or down.
And you'll see that we're moving the vertices
on the inside of the cushion here at the bottom.
If we don't want that to happen
we can disable effect back facing.
I'll undo that movement with control Z.
We've got a switch in the modify panel effect back facing.
We can turn that off or we can use the button
on this floating window over here,
click on effect back facing.
It's kind of hard to see sometimes
whether that's on or off.
And the problem here actually is that
when we turn it on or off from the modify panel
it doesn't necessarily update the state of this panel.
So that's kind of a bit of an issue
but in any event when effect back facing is on
we can see that those vertices at the bottom are lit up
meaning that they are part of the soft selection.
If effect back facing is off, then they're not lit up
and we're not affecting those back face polygons.
All right, cool, so I'll undo that as well.
Another very important thing to know about soft selection
is that transformations are destructive by default.
Let me demonstrate.
If I move these vertices up
and then just move them back down again
I'm not able to restore the original shape.
I've introduced this really problematic situation.
And I actually can't get back where I was
unless I used the undue buffer.
I'll hit control Z a couple of times.
The reason this is happening is
because as soon as we move something
and then release the mouse, watch what happens.
The vertex selection changed,
our soft selection isn't the same as it was
before we moved those vertices.
The fall off radius is going to resample the mesh
after every transform.
And when the mesh changes shape
the distances between sub objects will change
and therefore the soft selection region will change.
Okay, I'll undo that with control Z.
If we want to be able to non-destructively
restore that shape, then we can enable lock selection.
We've got a little padlock icon over here
in the floating window, or we can enable lock soft selection
in the modified panel.
Either way, if we move something
and then don't change our selection,
in other words, don't click on any other sub object,
then we can move that selection back down.
And we have essentially a reversible transform.
The soft selection will not change even
if the shape of the model changes.
Now that we understand how soft selection works
we can enable show end result
and then make a slight change here
and just move this vertex down a little bit.
And we can introduce depression in our seat cushion.
So we've just moved that one vertex, but we've also
adjusted all the nearby vertices via soft selection.
And then that in turn has changed the shape
of the control cage for our open sub div model.
We've introduced an even higher level of control
to our sub div modeling workflow.
That's how to use soft selection to manipulate sub objects
to produce smooth flowing surfaces.