Surfacing - Blender Foundations: The Essential Guide to Learning Blender 2.6 - page 177

the Material properties window, click the + sign in the material selector pane in the topmost panel. This
adds another material to the list. Press the Assign button below the material selector to set the selected
faces to use the new material. Tab out of Edit Mode. One important thing to note at this point is that
the new material is not completely new: It is an instance of the original material. You can tell because
both the original and the new one have the same name (“walls”), and there is a small number 2 to the
right of the material name. Just like the duplicates versus instances lesson from Chapter 3, the same rules
apply here. Any number of objects or material slots can be linked to the same material. Changing the
properties on one changes them for every other instance as well. As we want to create an entirely new
material, this won't do.
There are two ways to proceed. If the new material is going to be close to the original, you can just
hit the + sign to the right of the material name. This creates a completely independent copy of the
original material for you to work on. As it is not an instance, the adjustments you make to it will
not affect any other materials. However, if you want to start with a blank slate, click the “X” button
to unlink the material instance. When you do so, the material name turns into the New button. Click
it to add a material with default values. In order to tell if you've done it correctly, change the diffuse
color of the new material. It should change the color of the floor in the 3D view (in Solid mode),
but leave the walls alone. Figure 7.10 shows the room with the diffuse color of the floor material set to
a dull red.
Starting from the top, let's look at the settings I derived from observing some real, relatively new carpet.
The color of the reference isn't that important. In this case, we're more concerned about how the color
fits with the rest of the scene. The incoming sunlight already gives a bit of a warm feel, so I've decided
to augment that and use a warm color. Note that it's not highly saturated, though, much like real carpet.
It has an RGB make up of (0.33, 0.13, 0.14), of which the saturation value happens to be under 60%.
That's the diffuse color. There's nothing that remarkable about carpet when it comes to reflectivity one
way or another, so I'll start it fairly low, around 0.55. For the shader, however, we're going to branch
out a bit. Figure 7.11 shows the material settings.
In the earlier discussion of materials, we mentioned that the Minnaert shader worked nicely for lush fabrics.
This shader has a special control called Darkness , which defaults to 1.0. Pushed above the default, it
darkens faces that are pointing straight toward the viewer. Pushed below it, toward 0.0, it lightens faces
that point perpendicular to the viewer. The net effect is to somewhat mimic the variable sheen that certain
fabrics like velvet or silk exhibit. New carpet actually has a certain lush quality to it, so Minnaert is worth
a try. I've turned Darkness down to 0.0 so as to lighten sideward-facing geometry. Of course, it's a flat
floor, so the only “geometry” that is side facing is the fake roughness that will be generated by a texture
applied to the normals.
I don't note any specularity worth mentioning on real carpet, so I've set Specular Intensity to 0.0. With
Intensity at 0.0, I don't have to bother with the color, hardness, or shader for specularity. Remember that
with specularity, it won't be missed if it's not fairly prominent in your references, and if you put it in
where it's not needed it will mess with your ability to properly create the material.