       SippShaderPhong ambient diffuse specular spec_exp color
              [opacity]
              Create a shader that implements the Phong illumina-
              tion model.

              ambient is a value between 0.0 and 1.0 which deter-
              mines  how much of the base color of a surface that
              is visible when it is not illuminated by any  light
              source.

              diffuse  is  a value between 0.0 and 1.0 specifying
              how much light that is reflected diffusely from the
              surface.

              specular  is  a  value between 0.0 and 1.0 which is
              the fraction of color specularly reflected.

              spec_exp is the exponent in the specular  highlight
              calculation.   It specifies how "shiny" the surface
              is. Useful values are about 1 to 200, where 1 is  a
              rather dull surface and 200 is a very shiny one.

              color  is a list containing the red, green and blue
              values  for  the  surface.   Each  being  a  number
              between 0.0 and 1.0.

              opacity  describes  the  opacity  of a surface. 0.0
              means  totally  transparent,  1.0   means   totally
              opaque.  May be a list of red, green and blue opac-
              ity values or a single value to  be  used  for  all
              color channels.  Optional, default is 1.0.
