GLenum mode )

PARAMETERS
       face  Specifies the polygons that mode applies to.  Must be GL_FRONT for
             front-facing  polygons,  GL_BACK  for  back-facing  polygons,   or
             GL_FRONT_AND_BACK for front- and back-facing polygons.

       mode  Specifies  how  polygons  will be rasterized.  Accepted values are
             GL_POINT, GL_LINE, and GL_FILL.  The initial value is GL_FILL  for
             both front- and back-facing polygons.

DESCRIPTION
       glPolygonMode controls the interpretation of polygons for rasterization.
       face describes which polygons mode applies to: front-facing polygons  (‐
       GL_FRONT),  back-facing polygons (GL_BACK), or both (GL_FRONT_AND_BACK).
       The polygon mode affects only the final rasterization of  polygons.   In
       particular,  a polygon's vertices are lit and the polygon is clipped and
       possibly culled before these modes are applied.

       Three modes are defined and can be specified in mode:

       GL_POINT      Polygon vertices that are marked as the start of a  bound‐
                     ary  edge  are  drawn as points.  Point attributes such as
                     GL_POINT_SIZE and GL_POINT_SMOOTH control  the  rasteriza‐
                     tion  of  the  points.   Polygon  rasterization attributes
                     other than GL_POLYGON_MODE have no effect.

       GL_LINE       Boundary edges of the polygon are drawn as line  segments.
                     They are treated as connected line segments for line stip‐
                     pling; the line stipple counter and pattern are not  reset
                     between  segments  (see  glLineStipple).   Line attributes
                     such as GL_LINE_WIDTH and GL_LINE_SMOOTH control the  ras‐
                     terization of the lines.  Polygon rasterization attributes
                     other than GL_POLYGON_MODE have no effect.

       GL_FILL       The interior of the polygon is filled.  Polygon attributes
                     such  as  GL_POLYGON_STIPPLE and GL_POLYGON_SMOOTH control
                     the rasterization of the polygon.

EXAMPLES
       To draw a surface with filled back-facing polygons and  outlined  front-
       facing polygons, call glPolygonMode(GL_FRONT, GL_LINE);

NOTES
       Vertices  are marked as boundary or nonboundary with an edge flag.  Edge
       flags are generated internally by the GL when  it  decomposes  polygons;
       they can be set explicitly using glEdgeFlag.

ERRORS
       GL_INVALID_ENUM  is  generated if either face or mode is not an accepted
       value.