MirOS Manual: glFrontFace(3)


GLFRONTFACE(3G)     UNIX Programmer's Manual      GLFRONTFACE(3G)

NAME

     glFrontFace - define front- and back-facing polygons

C SPECIFICATION

     void glFrontFace( GLenum mode )

PARAMETERS

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

DESCRIPTION

     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 elimina-
     tion 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 counter-
     clockwise direction about the interior of the polygon.
     glFrontFace specifies whether polygons with clockwise wind-
     ing 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

     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 exe-
     cution of glEnd.

ASSOCIATED GETS

     glGet with argument GL_FRONT_FACE

SEE ALSO

     glCullFace(3G), glLightModel(3G)

MirOS BSD #10-current  Printed 03.04.2017                       1

Generated on 2017-04-03 16:26:17 by $MirOS: src/scripts/roff2htm,v 1.88 2017/01/29 00:51:06 tg Exp $

These manual pages and other documentation are copyrighted by their respective writers; their source is available at our CVSweb, AnonCVS, and other mirrors. The rest is Copyright © 2002–2017 The MirOS Project, Germany.
This product includes material provided by mirabilos.

This manual page’s HTML representation is supposed to be valid XHTML/1.1; if not, please send a bug report — diffs preferred.