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Whenever we start creating a texture, it's important to analyze the structures and patterns

of the thing we are creating.

It's often also useful to even research how it's made or how it works, to really get a

good grasp on the fundamental characteristics of the thing we're trying to reproduce.

So let's take a look at the brick pattern, and figure out the main things we need to

know to create a wall.

Firstly, on each row of bricks, we have a horizontally repeating pattern.

Then each row is also repeated vertically, but with an offset.

This is convenient, as it means that the brick pattern is just a grid with an offset along

an axis.

These types of tilings where the repetition is aligned with the sides of the tiles, are

the easiest to make.

This is in contrast with something like a Pythagorean tiling, which repeats at an angle

relative to the tile sides, which significantly complicates the maths.

Whenever we are reproducing a tiling pattern, it's important to define whether or not it

repeats, and if it does, define the unit of repetition.

In the case of the bricks we got lucky that it's just an offset grid pattern.

An important characteristic of brick walls, is the proportion of the bricks, and of the

tiling unit.

It's important to note that the tiling unit doesn't necessarily have the same proportions

as the bricks.

That's because between the bricks, there is the space taken up by the mortar, which usually

has an equal thickness on all sides.

Let's highlight the tiling unit with a black outline.

Here, the mortar is very thin, so the tiling unit is only slightly larger than a brick.

But if we start increasing the mortar width, the tiling unit also grows, and it's ratio

changes, approaching the ratio of a square.

So when implementing the repetition, it's important to use the ratio of the tiling unit,

including the mortar, rather than just the ratio of the bricks themselves.

Bricks can have many sizes, and there are several standards around the world.

For this course, I decided to go with standard UK bricks, as they have appealing proportions,

and convenient measurements, but we can always change the proportion of the bricks after

the fact.

UK brick dimensions are 215mm, by 102.5, by 65.

These dimensions may seem odd, or overly specific, but the beauty of these proportions is that

when we account for a nominal mortar join of 10mm, which adds 5mm all around the bricks,

we get a unit size of 225 by 112.5 by 75, which is a neat ratio of six:three:two.

So the ratio between the longest and shortest sides of the tiling unit is a convenient three:one.

If you want to know more about the different brick standards, the Wikipedia page on bricks

has some good information.

With the dimensions and tiling characteristics covered, let's look at the structure of a

wall.

The simplest wall will have a single stack of bricks, with each row being offset by half

a brick compared to the previous one.

However, more often than not, a single brick wall like that does not fulfill thermal or

structural requirements.

So it's very common for walls to have multiple adjacent layers.

For increased stability, these layers are usually connected together in one way or another.

These connections are called bonds, and are usually made by placing some bricks across

the layers, rather than lengthwise along the wall.

The bricks placed across the layers are called headers, referring to the fact that in the

resulting wall, we see the end of the bricks, which is called the header.

This is in contrast to the usual lengthwise bricks, which are called stretchers.

There are many patterns in which these headers can be laid, resulting in different structural

and aesthetic characteristics.

For our wall, we'll go with a common technique of having one full row of headers for every

few rows of stretchers.

You can find a lot of information on different bonds and bricklaying patterns on the Wikipedia

page about brickwork.

Now that we know the general structure of a wall, we can think of the specific effect

we want, and we can use our newfound bricklaying knowledge to make informed decisions on where

we might want to deviate from conventions.

A plain neatly constructed wall can be pretty boring from a shading perspective.

So to add some visual interest we can create some more variation.

For example, to avoid having too much of a regular pattern, we can randomize the offset

of each row of bricks, as well as randomize how often a header row is laid.

These kinds of things result in a more poorly constructed wall, but luckily, our wall doesn't

have to be structurally sound, so we can take some liberties for the sake of visual appeal.

And a poorly constructed wall can definitely add to that nice rustic look.

Another thing that can add visual appeal is having different types of color and texture

variation.

This brings us to the different ways in which variation can manifest itself.

Notably, there are two main classes of variation, discrete and continuous.

Discrete variation happens when we combine different distinct items.

For instance, the bricks themselves can have different colors, and if different colored

bricks are randomly mixed together at the time of construction, the wall ends up with

bricks having independently varying colors.

On the other hand, the effects of weathering over time will be continuous, and affect the

whole wall rather than individual bricks.

Taking note of these different types of variation is crucial when choosing how to generate the

different kinds of textures.

And to create an appealing texture, it is often a good idea to combine multiple types

of variation.