NAME    [Toc]    [Back]

       glFrontFace - define front- and back-facing polygons

SYNOPSIS    [Toc]    [Back]

       void glFrontFace(
               GLenum mode );

PARAMETERS    [Toc]    [Back]

       Specifies the orientation of front-facing polygons.  GL_CW
       and GL_CCW are accepted. The initial value is GL_CCW.

DESCRIPTION    [Toc]    [Back]

       In a scene composed entirely of  opaque  closed  surfaces,
       back-facing  polygons are never visible. Eliminating these
       invisible polygons has the obvious benefit of speeding  up
       the rendering of the image. To enable and disable elimination
 of back-facing polygons, call glEnable()  and  glDisable()
 with argument GL_CULL_FACE.

       The  projection of a polygon to window coordinates is said
       to have clockwise winding if an imaginary object following
       the  path from its first vertex, its second vertex, and so
       on, to its last vertex, and finally back to its first vertex,
  moves in a clockwise direction about the interior of
       the polygon.  The polygon's winding is said to be counterclockwise
  if the imaginary object following the same path
       moves in a counterclockwise direction about  the  interior
       of  the polygon.  glFrontFace() specifies whether polygons
       with clockwise winding in window coordinates, or  counterclockwise
  winding  in window coordinates, are taken to be
       front-facing. Passing GL_CCW to mode selects counterclockwise
  polygons  as  front-facing;  GL_CW selects clockwise
       polygons as front-facing.   By  default,  counterclockwise
       polygons are taken to be front-facing.

ERRORS    [Toc]    [Back]

       GL_INVALID_ENUM  is  generated  if mode is not an accepted
       value.

       GL_INVALID_OPERATION is generated if glFrontFace() is executed
  between  the  execution of glBegin() and the corresponding
 execution of glEnd().

ASSOCIATED GETS    [Toc]    [Back]

       glGet() with argument GL_FRONT_FACE

SEE ALSO    [Toc]    [Back]

       glCullFace(3), glLightModel(3)



                                                  glFrontFace(3G)