WEBVTT

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Hey guys, welcome to this

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video! We're going to be talking about normals here, so normal means

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90 degrees like this, think of a capital T! What do normals mean

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in Blender, Mikey? Well normals are used to describe lots of things,

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including the face direction. So if my hand was

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a face then that is the normal to it coming out, and this

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is the other side of the face. So if you look at a complex model with

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lots of faces on the outside of it, you can think of those like little elements of skin,

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and the normals should all be sticking outwards, just like the hairs on your skin should all be sticking

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outwards we hope. We don't want any ingrowing normals here! No! So

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that's what you need to remember for now, get the normals around the right way. Michael will show you, in the video, how

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to tell just in the Scene View, whether a normal is around the right way or the wrong way. So

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that's really important! Why is it important, Mikey, that the normals are outwards?

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Have you ever played a game where you stick your head through a piece of a wall or

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you're exploring the level, and suddenly you see through the level? Well that's

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something called Backface Culling. Normals are very important because it tells

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something that's rendering your model which way to actually render.

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So normals talk about how light interacts with the surface. Now we're going into more

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detail about that later, but it basically means that as a light

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ray comes in, it has a reference angle to work out how it's going to bounce, or if it doesn't

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bounce, how brightly it's going to illuminate the surface. Light glancing a surface,

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if the surface is pretty dark. Light hitting the surface square on,

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the surface diffuses light very brightly. So then we're going to go into the details of

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that in your later study of rendering. Backface Culling is very common in game

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engines and in other places. Actually, you'll notice that Blender

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renders both sides of a face by default, so it doesn't use something called Backface

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Culling, unless you turn it on. But if you export your model to something like say Unity,

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a popular game engine, and the normals are around the wrong way, the

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faces that are back to front will just be invisible. So in fact, if you had every normal

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the wrong way around, for whatever reason, your model would actually be invisible

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when you imported it into another package. From the outside and visible from the inside.

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Invisible, yes! And then, 3D printing is another application where it's important that you have a closed model with all

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the normals pointing outwards. So there's an introduction to normals! I don't know

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if they need to know anymore today. No not at the moment. In the next lecture we'll show you how to

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work out normals in Blender! Fantastic!