Texture
In
the bulk of this book, as in the game industry, we will be using the
term “texture” to mean a 2D static image. What we refer to as textures
in this book are also sometimes called materials, or even tile sets
(from older games), but we will stick to the term texture. The one
exception in this book is that in this section we will talk about the
word texture as it is used in traditional art: painting, sculpture,
etc. A side note on vocabulary; keep in mind that vocabulary is very
important and can be a confusing aspect of working in the game
industry. There is much room for miscommunication. Different words can
often mean the same thing, and the same words can often mean many
different things. Acronyms can be especially confusing; RAM, POV, MMO,
RPG all mean different things in different industries. POV means
point-of-view in the game industry and personally owned-vehicle in the
government and also stands for Persistence of Vision. So to clarify,
the term “texture,” while usually meaning a 2D image applied to a
polygon (the face of a 3D object), in this section of this chapter it
will refer to an aspect of an image and not the image itself. We draw
this distinction for the following conversation on traditional art.
In traditional art there are two types of texture: tactile and visual.
Tactile texture
is when you are able to actually touch the physical texture of the art
or object. Smooth and cold (marble, polished metal, glass) is as much a
texture as coarse and rough. In art this applies to sculptures and the
like, but many paintings have thick and very pronounced brush or
palette knife strokes. Vincent Van Gogh was famous for doing this. Some
painters even add materials to their paint like sand to add more
physical or tactile texture to their work.
Visual texture
is the illusion of what the surface’s texture might feel like if we
could touch it. Visual texture is composed of fine highlights and
shadows. As computer game texture artists, we deal solely with this
aspect of texture. So, for example, an image on your monitor may look
like rough stone, smooth metal, or even a beautiful woman and if you
try and kiss that beautiful woman she is still just a monitor—not that
I ever tried that, mind you.
There
are many ways to convey texture in a two-dimensional piece of art. In
computer games we are combining 2D and 3D elements and must often
decide which to use. With 2D we are almost always forced to use
strictly 2D imagery for fine visual texture. And while the faster
processors, larger quantities of RAM, and the latest crop of 3D graphic
cards allow us to use larger and more detailed textures and more
geometry, a great deal of visual texture is still static and noticeably
so to a trained artist. This limitation is starting to melt away as
complex Shader Systems are coming into the mainstream of real-time
games. The real-time processing of bump maps, specular highlights, and
a long list of other more complex effects are adding a depth of realism
to our game worlds not even dreamed of in the recent past. This book
will teach you both the current method of building texture sets and the
ever-increasing method of building material sets that use textures and
shader effects together. We will discuss this more at length later in
the book, but for now you can see some visual examples of these
effects. In Figure 1-11 you can see how in the 2D strip the object
rotates but the effects stay static on the surface, while on the 3D
strip the object rotates and the effect moves realistically across the
surface.
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Figure
1-11: Visual texture is composed of fine highlights and shadows. A
shader allows for the real-time processing of visual texture, among
other effects, and adds much more realism to a scene as the surface
reacts with the world around it. In this example I used a specular map.
These effects are best seen in 3D, but you can see here that the
windows in the building on the top row have a reflection of the sky in
them and that reflection moves as the players does. The windows in the
building on the lower row are painted textures and stay the same no
matter where the player walks. The bottom two rows are close-ups to
help you see the effect. If you pick one window in the close-up images
and look closely, you will see that the cloud reflections are in
different places in each frame.
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The
game artist’s job is often considering what tools and techniques we
have at our disposal and choosing which best accomplishes the job. We
are often trading off between what looks good and what runs well. As
you begin to paint textures, you will find that some of the techniques
of traditional art don’t work in the context of game texturing. As a
traditional artist we usually do a painting that represents one static
viewpoint, and we can paint into it strong light sources and a great
deal of depth, but that amount of depth representation goes beyond
tactile texture and becomes faked geometry and looks flat in a dynamic,
real-time 3D world. As mentioned earlier in this chapter, this will not
work in a 3D game where a player can move about and examine the
texture. Once again we must choose what to represent using a static 2D
image, what can be processed in real time using a shader, and what must
be represented using actual geometry. There are many solutions for this
problem; among them are restricting the players’ ability to move around
the texture, removing the element of overt depth representation, or
adding actual geometry for the parts of the texture represented by the
overt depth representation (see Figure 1-12).
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Figure
1-12: There are several possibilities when dealing with overt depth
representation. Upper left: the pipes are painted into the texture and
totally lack any depth; notice how they dead end into the floor. Upper
right: restricting the players’ ability to move around the texture can
alleviate some of the problem. Lower left: adding actual geometry for
the parts of the texture that cause the overt depth is the best
solution if possible (this method uses less texture memory but more
polygons). Finally, lower right: adding the actual geometry into the
recess is an option that looks pretty interesting and actually allows
for a reduction of geometry. The removal of polygons from the backsides
of the pipes more than offsets the added faces of the recess.
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Color
We
all know what color is in an everyday fashion, “Get me those pliers. No
the ones with black handles. I said paint the house green. I didn’t
mean neon green!” That’s all fine for the civilian discussion of color,
but when you begin to speak with artists about color, you need to learn
to speak of color intelligently and that takes a little more education
and some practice. You will also learn to choose and combine color,
too. In games, as in movies, interior design, and other visual
disciplines, color is very important. Color tells us much about the
world and situation we are in. While I was at CMP, we developed a
massively multiplayer game that started in the town—saturated green
grass, blue water, butterflies—you get the picture, this was a nice and
safe place. As you moved away from town, the colors darkened and lost
saturation. The grass went from a brighter green to a less saturated
brownish-green. There were other visual clues as well. Most people can
look at grass and tell if is healthy, dying, kept up, or growing wild.
Away from town the grass was also long and clumpy, dying, and growing
over the path. But even before we changed any other aspect of the
game—still using the same grass texture from town that was well
trimmed—we simply lowered the saturation of the colors on the fly and
you could feel the life drain from the world as you walked away from
town. As you create textures you will most assuredly have some form of
direction on color choice, but maybe not. You might need to know what
colors to choose to convey what is presented in the design document and
what colors will work well together.
This
section lays out a simple introduction to the vocabulary of color,
color mixing (on the computer), and color choices and their commonly
accepted meanings. I decided to skip the complex science of color and
stick to the practical and immediately useful aspects of color. Color
can get very complex and esoteric, but you would benefit from taking
your education further and learning how color works on a scientific
basis. While this chapter will be a strong starting point, you will
eventually move on from working with only the colors contained in the
texture you are creating to how those colors interact with other
elements in the world, such as lighting. To start with, however, a game
texture artist needs the ability to communicate, create, and choose
colors.
First,
we will discuss the way in which we discuss color. There are many color
models, or ways of looking at and communicating color verbally. There
are models that concern printing, physics, pigment, and light. They
each have their own vocabulary, concepts, and tools for breaking out
color. As digital artists, we use the models concerning light since we
are working with colored pixels that emit light. A little later we will
take a closer look at those color systems from the standpoint of color
mixing, but for now we will look at the vocabulary of color. In game
development you will almost always use the RGB color model to mix color
and the HSV color model to discuss color. You will see that Photoshop
allows for the numeric input and visual selection of color in various
ways. When you discuss color choices and changes and then go to enact
them, you are often translating between two or more models. Don’t
worry; this is not difficult and most people don’t know they are doing
it.
First, we will look at the HSV model, which stands for Hue, Saturation, and Value
since this is the most common way for digital artists to communicate
concerning color. These three properties of color are the main aspects
of color that we need to be concerned with when discussing color. In
Figure 1-13 you can see examples of these aspects of color.
- Hue is the name of the color (red, yellow, green).
- Saturation (or Chroma) is the strength or purity of the color.
- Brightness is the light or darkness of the color.
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Figure 1-13: In this image you can see a representation of HSB—Hue, Saturation, and Brightness.
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Hue
Most
people use the word “color” when referring to hue. While there are
many, many colors, there are far fewer hues. Variations of saturation
and brightness create the almost unlimited colors we see in the world.
Scarlet, maroon, pink, and crimson are all colors, but the base hue is
red.
Understanding
color and its various properties is best done with visual examples. The
most often used method is the Color Wheel developed by Johannes Itten.
We will look at the Color Wheel a little later. In Photoshop you will
recognize the Color Picker, which allows for various methods for
choosing and controlling color, both numerically and visually. The
Color Picker has various ways to choose color, but the most commonly
used is RGB (Red, Green, Blue)—Figure 1-14.
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Figure 1-14: Here are Color Pickers from various applications.
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Saturation
Saturation
quite simply is the amount of white in the color. In Figure 1-15 you
can see the saturation of a color being decreased as white is added. If
you have access to a software package like Photoshop and open the color
picker, you can slide the picker from the pure hue to a less saturated
hue and watch the saturation numbers in the HSB slots go down as the
color gets less saturated. Notice how the brightness doesn’t change
unless you start dragging down and adding black to the color. Also, you
may want to look down at the RGB numbers and notice how the red in RGB
doesn’t change, but the green and blue do.
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Figure 1-15: The saturation of the color red at 100% and decreasing to 0% by adding white.
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Brightness
Brightness
is the amount of black in the color. In Figure 1-16 you can see the
brightness of a color being decreased. As in the previous example
discussing saturation, you can open the color picker in Photoshop and
this time, instead of decreasing the saturation, you can decrease the
brightness by dragging down. You can look at the HSB and the RGB slots
and see the brightness numbers decreasing. Also notice that this time
in the RGB slots the red numbers decrease, but the blue and green are
already at zero and stay there.
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Figure 1-16: The brightness of the color red at 100% and decreasing to 0% by adding black.
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Like
most other aspects of color, brightness is affected by other factors.
What colors are next to each other? What are the properties of the
lights in the world? Another job the texture artist needs to do is to
make sure the textures in the world are consistent. That involves
balancing the hues, saturation, and brightness of the color in most
cases. Figure 1-17 depicts an example of a texture that may have looked
okay in Photoshop, but needed to be corrected to fit the scene. You can
see that a great deal of contrast and intensity of color makes tiling
the image a greater challenge.
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Figure
1-17: Here is an example of a texture that may have looked okay in
Photoshop, but needed to be corrected to fit in the scene correctly.
This is a subtle example. Notice the patch of exposed stone in the
concrete on the building that repeats?
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