       SippShaderPlanet ambient specular c3 [opacity]
              This  shader  is a somewhat specialized shader that
              produces a texture that resembles a planet surface.
              The  planet is of the Tellus type with a mixture of
              oceans and continents. Some of the surface is  cov-
              ered  by semi-transparent clouds which enhances the
              effect greatly. On the other hand,  no  polar  caps
              are provided and this decreases the realism.

              The  texture is 3-dimensional, so it is possible to
              create cube planets or even  planets  with  cut-out
              parts  that  still  have surfaces that resemble the
              earth surface. The texture is not scalable, and  is
              designed to be used with texture coordinates in the
              range -1.0 to 1.0, e.g. a unit  sphere.  Of  course
              the  world coordinates need not have the same order
              of magnitude.

              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.

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

              c3 is the shininess of the surface where 0.0 is the
              most shiny and 1.0 is the most dull.

              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.
