- [Instructor] When you're designing your Class A surfaces,
there are three things you have to consider:
your primaries, your secondaries, and your tertiaries.
Your primary slabs are your biggest, most general shapes.
They basically capture most of the intent.
Your secondaries, these blue surfaces here
are typically your blends between primary surfaces.
These primary surfaces have a nice general flow
capturing the largest slabs, over built geometry.
So easier to overbuild and come back
and trim things up as necessary.
So to connect these primary slabs,
we put these secondary surfaces in,
and oftentimes, where secondaries
and other primaries come together
to form these little, almost ball corners,
they're called tertiary surfaces.
These are typically the most mathematically complex
because they are built off of blend surfaces,
which they themselves are relatively complex.
For every order of continuity
that you require out of a surface,
you have additional math
that needs to be imparted on that surface,
and coming off of your primary surfaces which,
even though they're the biggest shapes,
they should be the simplest
mathematical representations of shape in your part.
We want to try to minimize the amount of math in these,
and the reason is because every downstream function
is going to increase the complexity of said surfaces,
so the next surface built off of it's going to be
a little more complex, and so on and so forth
until we get into our tertiary surfaces.
As you can see here, generally speaking
our tertiary surfaces, these little ball corners,
are the last things that we build.
These are the things that are just taking, in this case,
a tight little corner, wrapping it around
these big, gentle blends,
and just finishing off those surfaces.
So when you're laying out these patches,
when you're laying out your design,
you want to try to encapsulate as much of that design
with your primaries, and then think about
where your tangencies are going to go
to bridge across those primaries
with your initial secondaries,
and then to close everything off
with that final tertiary surface.