- Let's talk about edge smoothing.
That is the ability to make an edge appear hard or soft.
And that's very important for realism.
Remember that a polygon object is made
out of all straight lines.
If we want to give the illusion of curvature
then we need more segmentation in that curved area.
But it's always made out of straight lines.
And additionally if we want it to look curved,
we will want to use a technique called edge smoothing
to create a gradient or a smooth edge in a curved area.
And sometimes that can be an issue
especially when curved edges are rendered as hard
or hard edges are rendered as curved.
And we're seeing the latter case here.
In a version of the bullion walls courtyard object.
Remember in the previous movies, we added more detail
and we made this a little bit better.
But we didn't solve all the problems in this version.
If I orbit around with Alt and middle mouse
we can see that there's still some shading artifacts.
And if I select that object, we can see
that I've got my selection outlining turned back on again.
We turned that off previously.
Just remember to turn that on or
off using alt to J, let me hide those hedged faces
with F four and go into the modify panel.
And this is a bullion.
We're going to leave it as a bullion for now.
But again just orbit around with Alt and middle mouse.
And at certain angles
you can see you've got some shading artifacts.
And that's because these edges in these areas,
are being interpreted as soft or smooth edges.
And we want them to be hard edges.
We can change the status of whether an edge is determined
hard or soft.
In a couple of different ways.
We can apply a modifier to the object and just globally,
automatically smooth the object.
And that will perform a test
on every angle between two adjacent polygons.
And if that angle falls between a certain threshold
then that edge will be smooth.
If it's above that threshold, we will get a hard edge.
The other way to adjust edge smoothing is
on a per sub object basis.
We can select particular sub objects
and explicitly determine
whether we want those to be hard or soft.
So let's do the modifier approach first.
I'll select my walls, courtyard object.
And in the modifier list
I want to add a modifier called smooth.
Now not to be confused with mesh smooth.
That's actually going to change the level of detail.
That's a subdivision surface technique.
We just want plain old ordinary smooth.
Add that.
And with the default parameters
it's actually solved the problem for us completely.
So I can turn my selection highlighting back off again
with alt J so we can see this a little bit better.
So we have no issue here, everywhere on that model.
We now have hard edges, which is what we want in this case.
With a smooth modifier, with auto smooth disabled.
We're telling the object we want all
of the edges to be hard edges.
Okay.
So if I do enable auto smooth and then play around
with this threshold value, then we will start to see some
of those issues creep back in, again.
As I increase the threshold
I'm going to be telling the modifier that I want more
and more of the model to be smooth.
So again, any pair
of adjacent polygon has an angle between them.
And if that angle is lower than this threshold value
then the edge between those polygons will be smoothed.
So with a threshold above 90 degrees.
We're getting smoothing everywhere on the model.
And again, we don't want this smoothing.
We want hard edges everywhere.
So in this particular case, all we need to do is turn auto
smooth off, and we're getting hard edges everywhere.
Let's go a little bit deeper into this.
I'll turn my selection outlining back on again
with alt J.
And I'll create a teapot.
Go to the create panel standard preventives.
Teapot.
Click and drag
just to create the teapot.
Right click to exit.
Go back to the modified panel.
And add another smooth modifier to the teapot.
So we can see how the smooth modifier affects
a curved object.
Getting closer with the Z key.
And we can see
with default parameters with auto smooth disabled.
We get a faceted appearance everywhere.
And we can make that more extreme.
By going back down to the teapot parameters.
We can reduce the number of segments.
Bring that down to let's say five.
Now it's really obvious.
Now we're getting a faceted appearance everywhere
and all the edges are being drawn as hard edges.
Backup to the smooth modifier.
Enable auto smooth.
And we have a default threshold of 30 degrees.
So anywhere two polygons meet.
At an angle of less than 30 degrees,
will get a smooth edge or a soft edge.
And in these areas here
like specifically, on the spout of the teapot
we can see that some of these polygons are meeting
at an angle greater than 30 degrees.
And therefore we're getting a hard edge there.
As I increase the threshold value then,
more of the model is going to get smoothed.
So even just bringing
up a few degrees in this case, fix that spout.
If we look at the handle back here
we've got angles greater than in this case, 36 degrees.
So we'll have to keep increasing this
and we need to bring up quite a lot in this case
because it's such a low definition
or low level of detail object.
So with a threshold of about 50 degrees,
we're smoothing almost everything on the model.
If you want to make sure
that we're absolutely smoothing the entire model
and there will be no hard edges anywhere
then we just set the threshold to 180 degrees.
Now that doesn't apply to a situation like this here
because, these are actually two polygon shells are
two different disconnected pieces that are just going
to stuck on top of one another.
We can see that if we go into wire frame with F three.
So that's why we're getting a hard edge there's.
Because that's not actually a joint between two polygons.
We've actually got this spout actually penetrating
inside the bowl of the teapot.
All right, I'll go back to shaded mode with F three.
So that our global solution to smoothing.
We can add a smooth modifier
and then enable auto smooth and set some threshold.
And then any polygon pair that meets
at an angle lower than that threshold will be smooth.
There are lots of other ways to adjust smoothing.
We'll look at smoothing groups in the next moving.