Hey guys, welcome to this
video! We're going to be talking about normals here, so normal means
90 degrees like this, think of a capital T! What do normals mean
in Blender, Mikey? Well normals are used to describe lots of things,
including the face direction. So if my hand was
a face then that is the normal to it coming out, and this
is the other side of the face. So if you look at a complex model with
lots of faces on the outside of it, you can think of those like little elements of skin,
and the normals should all be sticking outwards, just like the hairs on your skin should all be sticking
outwards we hope. We don't want any ingrowing normals here! No! So
that's what you need to remember for now, get the normals around the right way. Michael will show you, in the video, how
to tell just in the Scene View, whether a normal is around the right way or the wrong way. So
that's really important! Why is it important, Mikey, that the normals are outwards?
Have you ever played a game where you stick your head through a piece of a wall or
you're exploring the level, and suddenly you see through the level? Well that's
something called Backface Culling. Normals are very important because it tells
something that's rendering your model which way to actually render.
So normals talk about how light interacts with the surface. Now we're going into more
detail about that later, but it basically means that as a light
ray comes in, it has a reference angle to work out how it's going to bounce, or if it doesn't
bounce, how brightly it's going to illuminate the surface. Light glancing a surface,
if the surface is pretty dark. Light hitting the surface square on,
the surface diffuses light very brightly. So then we're going to go into the details of
that in your later study of rendering. Backface Culling is very common in game
engines and in other places. Actually, you'll notice that Blender
renders both sides of a face by default, so it doesn't use something called Backface
Culling, unless you turn it on. But if you export your model to something like say Unity,
a popular game engine, and the normals are around the wrong way, the
faces that are back to front will just be invisible. So in fact, if you had every normal
the wrong way around, for whatever reason, your model would actually be invisible
when you imported it into another package. From the outside and visible from the inside.
Invisible, yes! And then, 3D printing is another application where it's important that you have a closed model with all
the normals pointing outwards. So there's an introduction to normals! I don't know
if they need to know anymore today. No not at the moment. In the next lecture we'll show you how to
work out normals in Blender! Fantastic!