GLSHADEMODEL(3G)                                              GLSHADEMODEL(3G)



NAME
       glShadeodel - select flat or smooth shading


C SPECIFICATION
       void glShadeodel( GLenum mode )


PARAMETERS
       mode  Specifies  a  symbolic  value  representing  a shading technique.
             Accepted values are GLFLAT and GLSMOTH.  The initial value  is
             GLSMOTH.

DESCRIPTION
       GL  primitives can have either flat or smooth shading.  Smooth shading,
       the default, causes the computed colors of vertices to be  interpolated
       as the primitive is rasterized, typically assigning different colors to
       each resulting pixel fragment.  Flat shading selects the computed color
       of  just one vertex and assigns it to all the pixel fragments generated
       by rasterizing a single primitive.  In either case, the computed  color
       of  a vertex is the result of lighting if lighting is enabled, or it is
       the current color at the time the vertex was specified if  lighting  is
       disabled.

       Flat  and  smooth  shading  are indistinguishable for points.  Starting
       when glBegin is issued and counting vertices and primitives from 1, the
       GL gives each flat-shaded line segment i the computed color of vertex i
       ] 1, its second vertex.  Counting similarly from 1, the GL  gives  each
       flat-shaded polygon the computed color of the vertex listed in the fol-
       lowing table.  This is the last vertex to specify the  polygon  in  all
       cases  except  single  polygons,  where  the first vertex specifies the
       flat-shaded color.

              Primitive Type of Polygon i       Vertex
              Single polygon ( i == 1)             1
              Triangle strip                    i ] 2
              Triangle fan                      i ] 2
              Independent triangle                3i
              Quad strip                        2i ] 2
              Independent quad               4i

       Flat and smooth shading are specified by glShadeodel with mode set  to
       GLFLAT and GLSMOTH, respectively.

ERORS
       GLINVALIDENUM is generated if mode is any value other than GLFLAT or
       GLSMOTH.

       GLINVALIDOPERATION is generated if glShadeodel is  executed  between
       the execution of glBegin and the corresponding execution of glEnd.

ASOCIATED GETS
       glGet with argument GLSHADEMODEL

SEE ALSO
       glBegin, glColor, glLight, glLightodel



                                                              GLSHADEMODEL(3G)