
         Tutorial 3: Anisotropic Specularity

         Another great feature of Gaffer is Anisotropic Specularity. This
         allows for realistic shading of surfaces such as scratched or
         polished metals, hair, or threads, where the surface has a very
         complex specular behavior due to the fine detail on their
         surface. In this tutorial we will create two surface types that
         in real life would show this type of specular behavior, a brass
         surface and an aluminum alloy surface.

         Load "aniso_urn.lws" into Layout. This is the scene as we left it
         from the last last tutorial.

         Anisotropic highlights are broadened in certain directions. You
         define these directions by the use of an auxiliary object that
         can be positioned and rotated to tell Gaffer the behavior you
         want. We'll start by adding this control object, so open the
         objects panel and choose "Add Null Object". Parent the null to
         the urn, and stretch the null along it's +Z axis so we can
         clearly see which way it is pointing. (This stretching is
         unnecessary but helps us see the direction much easier.) Rotate
         the null 90 degrees in pitch. This makes the null's Z axis point
         along the Y axis of the urn. We'll be adding a "Cylindrical"
         anisotropic geometry, causing the highlights to be broadened
         along this axis.

         Now we'll set up the surface to have a brass-like behavior. Open
         the surfaces panel and choose the urn's surface. For this example
         set the surface color to 225-175-0, set diffuse to 50% and
         reflectivity to 0%. Open Gaffer's options.

         We want to turn on those fill lights, since metals respond much
         better to multiple lights. Set the "boost" of the Fill lights to
         to 50%. As before, let's set our preview up to show the surface.
         Set "Preview Diffuse" to 50%, "Preview Specular" to 100% and the
         "Preview Surface" color to 225-175-0.

         Now we'll define the anisotropy itself. In the "Anisotropy
         Direction" section of Gaffer, type in "Null" (it's case
         sensitive) for the "Control Object" and set the type to
         "Cylindrical". If you've done everything correctly so far you
         will notice the green "Y" next to the "Control Object" field.
         This means "YES, I've found the object." If you've misspelled the
         object or the object doesn't exist, you will get a big "N" for
         NO.

         This type of surface is much easier than the previous lacquered
         surface. A single fairly broad highlight with a similar tint to
         the base surface works very well. Set the "Secondary Specularity"
         to 0% to disable the second highlight. For the "Primary
         Specularity" section, enter a color of 225-175-0, gloss of 60%,
         sharp of 20% and "Anisotropy" of 100%. Looking at the preview,
         this looks great. Return to Layout and render a frame. Applied to
         our urn, we can see the more subtle effects of the shading. The
         highlight could be a slightly brighter tint, so back in Gaffer,
         right click and drag on the specularity color gadget to raise its
         brightness a bit.

         The next example depicts an aluminum alloy as seen on thermoses,
         camping utensils, sprockets, gears, and all kinds of other
         fixtures. We've covered the features needed to get a surface such
         as this in the last two examples, so we'll just load a ready-made
         surface. LightWave's saved surfaces can include plugins like
         Gaffer with no problem!

         Load "aniso2.srf" onto the urn's surface using LW's "Load
         Surface" button. Open up Gaffer's options and see how this
         surface is defined. We've used two specular hotspots in
         combination with anisotropy for each. Experiment with various
         settings to suit your tastes! We hope we've given you enough
         information in the last few tutorials to get you started with
         realistic specularity with Gaffer.



