Materials in practice
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## Materials in practice

Relevant to Blender v2.31

In this section we look at how to set up the various material parameters in Blender, and what you should expect as a result.

Figure 10.4. Add new material.

Once an Object is selected, by pressing the F5 key or , you switch to Shading context and the Material Buttons window appears. This window will appear terribly empty, unless the Object already has a material linked to it. If there is no linked material, add a new one with the menu button (Figure 10.4, “Add new material.”).

Once you have added a material the buttons will appear as shown in Figure 10.5, “Material Buttons.”. Four panels are present, left to right: a `Preview` panel, a `Material` panel, a `Shader` panel and a `Texture` panel. We will concentrate on the first three, for now.

Figure 10.5. Material Buttons.

The `Preview` panel shows the material preview. By default it shows a plane seen from the top, but it can be set to a sphere or a cube with the buttons on the right of the panel (Figure 10.6, “Material Preview, plane (left) sphere (middle) and cube (right).”).

Figure 10.6. Material Preview, plane (left) sphere (middle) and cube (right).

### Material Colors

The `Material` Panel (Figure 10.7, “Material colors buttons.”) allows, among other things, setting of the material colors.

Figure 10.7. Material colors buttons.

Each material can exhibit up to three colors:

- The basic material color, or the Diffuse color, or, briefly the Color tout court (`Col` button in the interface) which is the color used by the diffuse shader.

- The Specular color, indicated by the `Spe` button in the interface, is the color used by the specular shader.

- The Mirror color, indicated by the `Mir` button in the interface, is the color used by special textures to fake mirror reflections. (You'll find more information on this in the Environment Mapping section).

The aforementioned buttons select the pertinent color, which is shown in preview immediately to the left of each button. The three sliders at the right allow you to change the values for the active color in both a RGB scheme and in a HSV scheme. You can select these schemes via the `RGB` and `HSV` buttons at the bottom.

The `DYN` button is used to set the Dynamic properties of the Object in the RealTime engine (which is outside the scope of this book), while the four buttons above relate to advanced Vertex Paint and UV Texture.

### The Shaders

The `Shader` panel (Figure 10.8, “Material Shader buttons.”) displays two MenuButtons allowing you to select one diffuse shader (Figure 10.9, “Material Diffuse shaders.”) and one specular shader (Figure 10.10, “Material Specular shaders.”).

Figure 10.8. Material Shader buttons.

Figure 10.9. Material Diffuse shaders.

Figure 10.10. Material Specular shaders.

The two sliders on the side, valid for all shaders, determine the intensity of the Diffusion and Specular phenomena. The `Ref` slider has a 0 to 1 range whereas the `Spec` has a 0 to 2 range. Speaking in strictly physical terms, if A is the light energy impinging on the object, Ref times A is the energy diffused and Spec times A is the energy specularly reflected. To be physically correct this must be Ref + Spec < 1 or the object would radiate more energy than it receives. But this is CG, so don't be too strict on physics.

Depending on the chosen shader other sliders may be present, allowing you to set the various parameters discussed in the introduction.

For the sake of completeness, Figure 10.11, “Shader overview.” shows all possible combinations. Of course, since there are so many parameters, these are just a small sample.

Figure 10.11. Shader overview.

### Tweaking Materials

The remaining material buttons both in the `Material` and `Shaders` panels perform some interesting effects.

Figure 10.12. Additional material sliders.

Figure 10.12, “Additional material sliders.” shows some interesting sliders. `Alpha` governs the opacity of the material; 1 is fully opaque and 0 is fully transparent. `SpecTra` forces specularity highlights on transparent bodies to be opaque. `Shadeless` makes the material insensitive to its shading, giving it a uniformly diffuse color.

In the `Shaders` panel, the `Emit` slider gives, if non zero, an emitting property to the material. This property makes material visible even without lights and can be itself a source of light if the Radiosity engine is used. (Figure 10.13, “Regular material (left), material with Alpha < 1 (center) and material with Emit > 0 (right).”).

Figure 10.13. Regular material (left), material with Alpha < 1 (center) and material with Emit > 0 (right).

The remaining column of buttons (Figure 10.14, “Material special buttons.”) activates some special features. Top `Halo` Button makes the material an 'Halo' material, which will be described later on. By default the `Traceable`, `Shadows` and `Radio` are activated. The first allows the material to cast shadows, while the second allows the material to receive shadows; the third allows the material to be taken into account if a Radiosity rendering is performed.

Figure 10.14. Material special buttons.

`Wire` renders the Object as a wireframe. `ZTransp` is necessary to activate the Alpha transparency effect.

The other buttons are not used that often and are described in the reference section at the end of the book.

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