Surfacing - Blender Foundations: The Essential Guide to Learning Blender 2.6 - page 188

mirror. But it's not. It sat in a room
for several years, and people set drinks
and books and papers on it, and kids
scratched it, and no one has even
thought of dusting it for weeks. In fact,
it's a real table, and real stuff happens
to it, so the gloss finish isn't going to
be perfect.

LMB click on the second texture
channel, and click New to add
another texture. This will be another
image texture, using UV coordinates.
For this one, though, we're going to
use a file called spottywall.jpg. It's
mostly black and white and contains
ugly dirt stripes and grain. Apply it to
the table's Specular Intensity on the
Influence panel. When you do it,
nothing happens. This is because
something like Specular Intensity rep-
resents a single value from 0.0 to 1.0,
while the texture image is in RGB.
In order to make an RGB texture affect one of the single-value influence fields, enable RGB to Intensity
at the bottom of the panel. Also, if you recall from the previous example, to replace a material property
like Intensity, you have to set the material's baseline to 0.0. So, “steal” the influence value of 0.4 for the
texture's Specular Intensity influence from the Material window, setting the main material property to 0.0.

Figure 7.22 The Smart Project result from the sample table.

Figure 7.23 shows the table as it is on the bottom, and with an enhancement on the top. It's pretty obvious
that the one on the top looks significantly better. This is one of those times that ray tracing, which we
tried to avoid when working with lighting, makes a huge difference. Blender can create real reflections,
and, due to a recent coding project, is much faster at it now than it used to be. In a case like this table,
we're going to just have to bite down on something leather and use it. The fact is that there's no way
around achieving the look of a glossy, reflective table without mirroring.

Back in the Material window, find and enable the Mirror panel. Reflectivity is the percentage value of
light that is reflected. A perfect mirror is 100% (1.0) reflective. Observing the reference image, it's clear
that this is not the case. Trial and error indicates that the correct value for reflection sits around 0.48.
Unfortunately, that was the easy part. One of the aspects of reflective materials is that their levels of reflec-
tivity can differ based on the viewing angle. For example, looking across a pond with your head at ground
level will show a near-perfect reflection. However, looking straight down into the water will show almost
no reflection. This effect is measured and reproduced by the Fresnel control on the Mirror panel.