This chapter is from the book
This chapter is from the book
This chapter is from the book
Textures, Shaders, and Materials
Applying graphical assets to 3D models can be daunting if you are not familiar with it. Unity uses a simple and specific workflow that gives you a lot of power when determining exactly how you want things to look. Graphical assets are broken down into textures, shaders, and materials. Each of these is covered individually in its own section, but Figure 3.5 shows you how they fit together. Notice that textures are not applied directly to models. Instead, textures and shaders are applied to materials. Those materials are in turn applied to the models. This way, the look of a model can be swapped or modified quickly and cleanly without a lot of work.
)
FIGURE 3.5 The model asset workflow.
Textures
Textures are flat images that get applied to 3D objects. They are responsible for models being colorful and interesting instead of blank and boring. It can be strange to think that a 2D image can be applied to a 3D model, but it is a fairly straightforward process once you are familiar with it. Think about a soup can for a moment. If you were to take the label off of the can, you would see that it is a flat piece of paper. That label is like a texture. After the label was printed, it was then wrapped around the 3D can to provide a more pleasing look.
Just like all other assets, adding textures to a Unity project is easy. Start by creating a folder for your textures; a good name would be Textures. Then drag any textures you want in your project into the Textures folder you just created. That’s it!
Shaders
If the texture of a model determines what is drawn on its surface, the shader is what determines how it is drawn. Here’s another way to look at this: A material contains properties and textures, and shaders dictate what properties and textures a material can have. This might seem nonsensical right now, but later when we create materials you will begin to understand how they work. Much of the information about shaders is covered later this hour, because you cannot create a shader without a material. In fact, much of the information to be learned about materials is actually about the material’s shader.
Materials
As mentioned earlier, materials are not much more than containers for shaders and textures that can be applied to models. Most of the customization of materials depends on which shader is chosen for it, although all shaders have some common functionality.
To create a new material, start by making a Materials folder. Then right-click the folder and select Create > Material. Give your material some descriptive name and you are done. Figure 3.6 shows two materials with different shaders selected. Notice how they each have a base texture, main color, tilling and offsets, and a preview of the material (blank now because there is no texture). The Shiny material, however, uses a specular shader and comes with properties for specular color and shininess. All these properties are covered later in this hour.
)
FIGURE 3.6 Two materials with different shaders.
Shaders Revisited
Now that you understand textures, models, and shaders, it is time to look at how it all comes together. Unity has a lot of built-in shaders, but this book is concerned with only a few of the Normal family of shaders. These shaders are the most basic and should be useful for everyone. Table 3.1 lists some of the basic shaders and describes them.
TABLE 3.1 Basic Normal Family of Shaders
|
Shader |
Description |
|
Diffuse |
Diffuse is the default shader for materials and is also the most basic.Light is evenly distributed across the diffuse object's surface. |
|
Specular |
Specular textures make an object look shiny. If you want to make an object seem to reflect a lot of light, this is the shader to use. |
|
Bumped |
Bumped shaders are generally used in conjunction with other shaders (as in bumped-diffuse or bumped-specular). These shaders use a normal map to give the flat texture a 3D, or bumpy, look. These are a great way to give your models a lot of physical detail without requiring complex modeling. |
Now that you are familiar with a few of the built-in shaders, it is time to look at some of the common shader properties that you will be working with. Table 3.2 describes the common shader properties.
TABLE 3.2 Common Shader Properties
|
Property |
Description |
|
Main Color |
The Main Color property defines what color of ambient light shines on the object.This does not change the color of the object itself; it just makes the object appear different. For example, an object with a blue texture and a yellow main color will not turn yellow but green (because blue with yellow light looks green). If you want your model's color to remain unchanged, select white. |
|
Specular Color |
The Specular Color property determines what color the "shiny" parts of a specular model are. Generally speaking, this will be white unless you intend for it to appear as if another color of light is shining on the object. |
|
Shininess |
The Shininess property determines how shiny a specular object is. |
|
Texture |
The Texture block contains the texture you want to apply to your model. |
|
Normal Map |
The Normal Map block contains the normal map that will be applied to your model. A normal map can be used to apply bumpiness to a model. This is useful when calculating lighting to give the model more detail than it would otherwise have. |
|
Tiling |
The Tiling property defines how often a texture can repeat on a model. It can repeat in both the x and y axes. |
|
Offset |
The Offset property defines whether a gap will exist between edges of the object and the texture. |
This might seem like a lot of information to take in, but once you become more familiar with the few basics of textures, shaders, and materials, you’ll find this a smooth process.
Try it Yourself: Applying Textures, Shaders, and Materials to Models
Let’s put all of our knowledge of textures, shaders, and materials together and create a decent-looking brick wall:
- Start a new project or scene. Note that creating a new project will close and reopen the editor.
- Create a Textures and a Materials folder.
- Locate the Brick_Texture.png file in the book files and drag it into the Textures folder created in step 2.
Add a cube to the scene. Position it at (0, 1, –5). Give it a scale of (5, 2, 1). See Figure 3.7 for the cube properties.
FIGURE 3.7 The properties of the cube.
- Create a new material (right-click the Materials folder and select Create > Material) and name it BrickWall.
- Leave the shader as Diffuse, and in the texture block click Select. Select Brick_Texture from the pop-up window.
- Click and drag the brick wall material from the Project view onto the cube in the Scene view.
- Notice how the texture is stretched across the wall a little too much. With the material selected, change the value of the x tiling to be 3. Now the wall looks much better.
- Add a directional light to your scene (click GameObject > Create Other > Directional Light). Position it at (0, 10, –10) and give it a rotation of (30, 0, 0). We will discuss lighting more in a later hour. This is just here to make your brick wall “pop.”
You now have a textured brick wall in your scene. Figure 3.8 contains the final product.
FIGURE 3.8 The final product of this Try It Yourself.
)
){kind=link}