Materials

In this section, we'll be talking about materials. Materials give objects color, mirroring, specularity ("shiny"), transparency, and the also determines how the object is rendered. This will be a fairly brief lesson and we won't go into too much detail, but I hope this will give you a general understanding and teach you enough to use materials effectively.

If you select the default cube and go to the Materials Tab in the Properties window, you will see what is displayed at left. This is the default material for all mesh objects that you add to the scene. You can see that it is set to a grayish color. We can change this color to any color we wish. This is done in the Diffuse panel. Diffuse merely identifies the light that is reflected off the surface of the object.

Diffuse:
Go ahead and click on the color bar under Diffuse. On the color wheel that comes up, go ahead and pick any color you wish. I'll choose a sort of magenta color for now.

Then, underneath the color bar, you can choose how much light is reflected (aka the Intensity). You can slide this bar left and right to adjust it or hold Shift and then click on it to type in a more exact number.

Specular:Specularity is in basic terms, the shininess of the object or the strong reflective spots. If you slide the Intensity bar around you will notice that the bright reflective spot on the Preview get brighter and larger or smaller.

You can also choose the color of the specularity. For example if you wanted the bright reflective spots to be more of a cool blue color, you could adjust the color of the specular appropriately.

The last option is the Hardness of the specular which is basically the size of the highlight. The higher the Hardness is, the smaller the highlight will be.

Transparency:Transparency allows you to adjust how much you can see through the object. For most things you'll probably leave it off like it is now but it is useful for windows, glass, etc.

Turn it on and click on the arrow to see the other options.

As you can see, there are really two options for how to render the transparency. The currently selected option, Z Transparency just kind of "fades out" the object based on the alpha value you give it. Currently the alpha is 1 so there will be no transparency, but if you turn that down, you'll be able to see through the object.

The Specular of the Transparency determines how transparent to make the specular highlights.

The Fresnel effect is a little hard to explain, but essentially it is adjusting how transparent the object is based on the angle it is at. Just play around with the setting to figure out what its doing.

There is another method of transparency that is usually much more realistic but in turn means a lot more render time. Raytracing "traces" light coming from around it and bends it through the transparency of the objects as it might in the real world.

                    There's a leaf behind this sphere that you can see warped through the transparency.

Now, click on Raytrace to switch over.

Again, there are the same Alpha, Specular, and Fresnel options as before. But this time, there are whole bunch of other options.

The most important option is the Index of Refraction (IOR) which put simply is the angle at which light is "bent" through the object. In the real world, certain materials have certain IOR values that can be used in Blender. Here's a list of some common materials and their IOR values.

Filter determines how much the diffuse color is blended into the refractions. This creates a "denser" look to it.

Limit adjusts how deep light can travel through the object before it becomes blended in with the diffuse color.

The Gloss options allow you to make the refractions more or less clear. A lower value creates blurry refractions while higher values produces clearer ones.

The rest of the options are more complicated and not worth getting into yet.

Mirror:
Mirror allows you to give objects a property that reflects what is around them.

The settings are pretty straightforward.

The Reflectivity is how reflective the material is and the color bar adjusts the "tint" of the reflection.

The Fresnel does the same thing as before only with mirroring. So, it adjusts the mirroring based on the angle of the object.

Gloss adjusts the clarity of the reflections.






Well, that's the main idea of the materials. Its always a good idea to try to learn something with different resources. Why not watch this quick video to get a better feel of materials (I feel this lesson was entirely to brief and unillustrated).
http://www.blendercookie.com/getting-started-with-blender-materials/