Bidirectional texture function

Okay kiddo, do you see the texture on your t-shirt? It's like a pattern or design, right? Well, imagine that we want to put that same pattern on a computer model of a shirt, like in a video game or movie. That's where a texture function comes in - it tells the computer how to put that pattern on the shirt in a way that looks realistic.

Now, sometimes we want the texture to change depending on where you're looking at it from. For example, if you look at your t-shirt from the front, you see one part of the pattern, but if you look at it from the side, you might see a different part of the pattern. That's where a bidirectional texture function comes in.

It's like having two different texture functions in one. So, when you look at the computer model from one direction, it uses one part of the texture function to make it look like the pattern is facing the right way. But when you look at it from a different direction, it uses a different part of the texture function to make it look like the pattern is facing the right way.

Basically, a bidirectional texture function helps things in a video game or movie look more realistic by making textures change depending on the direction you're looking at them from.