- [Instructor] When we look at a subdivision surface model
such as this cushion,
we may notice that it looks kind of soft
and mushy everywhere.
There are no sharp corners anywhere on it.
Well, we can add hard edges
or sharp corners to a subdivision surface model
in a couple of different ways.
One way is to simply add more edge loops
in the area where we want a corner.
For example, I might want to separate
the seat cushion from its base,
and that would look best if I had a really sharp corner
or angle between the two.
I can insert another edge loop here
and that would increase the curvature
between those two edge loops
and also flatten out the nearby areas
of adjacent polygons giving us a sharp corner.
However, that would come at the cost
of increased polygon count.
We can get around that problem
by using polygon creasing
that will allow us to keep the same polygon count
but get a nice sharp corner.
Let's see the issue around inserting an edge loop.
I'll select the seat cushion
and isolate it with Control + Alt + Q.
I've got the polygon statistics visible in the view port,
and we can see that chair task seat cushion
has about 4,600 polygons.
Let's insert a new edge loop to create a sharp corner.
From the modeling ribbon,
go into to modify mode
and click previous modifier a couple of times
to go down to the bottom of the stack.
We can get in closer Control + Alt and middle mouse.
As we saw previously we can insert an edge loop
from the edit panel
click on swift loop,
and then hover your mouse
and as you move it around you'll see a previous
of your new edge loop
you're about to create.
We're going to create one just below this corner edge loop
that's already there.
So hover your mouse there.
Click your mouse to create that edge loop
and then right click to exit the swift loop tool.
So let's now turn on show end result.
In our statistics we see our subdivided polygon count
after we've inserted that one edge loop.
Now our poly count is 5,120 polygons,
5,120.
We just increased the polygon count by over 500
which is about 10% of the entire object in this case.
And that's significant.
We don't really want to do that if we don't have to.
In the modify panel if we select
the OpenSubDiv modifier
and disable Isoline display
and get in very close
we can see that we've substantially increased the level
of detail in that area.
It's not even a sharp corner
it's still kind of mushy
and additionally, all these polygons are much smaller
than their neighbors
and that's not very efficient.
We've increased the level of detail,
but it's excessive in this case.
It would be better if the polygons on the model
were a more consistent size relative to one another.
They should really only be small enough
to resolve the curvature
that our audience could actually see
from a normal viewing distance.
Now, we could micromanage this by going in
and deleting or removing individual edge loops
but that's not a good use of our time
we should use creasing instead.
I'll turn Isoline back on again.
So instead of inserting an edge loop
we crease the existing edge loop
and that will achieve a better effect
without increasing the level of detail.
Let's go back over to the modeling ribbon
and again go to the bottom of the stack
and we can disable "show end result,"
and let's delete or remove the edge loop
that we just created.
We'll go into edge sub-object mode
and it'll probably be selected
if it's not you can just double click on it
and we can remove it and all the associated vertices
with a keyboard shortcut Control + Backspace.
Now let's select the edge loop that we want to crease.
So just double click on any one of these edges
here in this corner area, double click
and all those edges are selected.
We can adjust creasing either from the modify panel
or from the ribbon.
In the modify panel, if we scroll down
in the edit edges roll out
we see edge properties, weight, crease, and depth.
These are data channels.
They represent information about sub-objects.
That information actually gets sent up the stack
to subsequent modifiers
and they can perform some work on that information.
For example, we can change the crease value
and that will be read by the OpenSubDiv modifier up here
in order to change the shape of the model.
We won't see any effect right now
unless we have "show end result" turned on.
So let's enable that
and we can also turn off edged faces in our view port
and make it a little bit easier to see.
I'll press F4
and orbit around to the other side,
frame that up so we can really see the effect clearly
and then increase the crease amount,
bring that up.
Our edges are still selected.
And as long as that crease amount is above about 0.3 or so
we're going to get a nice sharp corner there.
I'm bringing up all the way to a value of one.
We can also adjust the crease amount in the modeling ribbon.
It'll be found in the edges panel.
You'll need to expand the panel.
You'll see there's a big button at the bottom
and it's got a down facing arrow,
click on that and it opens up a little popup panel
from which we can access these same controls.
We can reduce the crease amount down to zero
or we can bring it up to value of one.
If we move our mouse away from that panel, it'll disappear.
If you want that to stick on your screen
you've got a little button here, a push pin icon
you can activate that.
And then that popup panel will remain regardless
of where you're mouse is.
Okay, I'll turn that back off again.
All right, we've just sharpened that corner
but we have not increased our polygon count.
Look over here in our statistics
we're still at 4,600 polygons.
All right, that's pretty cool.
We can see this even more clearly.
If we exit out of sub-object mode
and go back up to the top of our modifier stack
to the OpenSubDiv modifier
and disable Isoline
and finally re-enable edged faces with F4
and get in closer there.
So these polygons are really no smaller
than the ones around them.
So we haven't increased the level of detail.
We haven't introduced some excessive polygon count
that our audience will never see
and we've got a perfectly sharp corner there
that we didn't even have before.
So the crease workflow really is helpful.
All right, we can exit out of isolation
with Control + Alt + Q
and that is how to use edge creasing
in conjunction with OpenSubDiv.