GLFRONTFACE(3G) GLFRONTFACE(3G)

glFrontFace - define front- and back-facing polygons

void glFrontFace( GLenum mode )












  

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










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.








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.








glGet with argument GL_FRONT_FACE








glCullFace, glLightModel