Skip site navigation (1)Skip section navigation (2)

FreeBSD Manual Pages

  
 
  

home | help
GLFRONTFACE()							 GLFRONTFACE()

NAME
       glFrontFace - define front- and back-facing polygons

C SPECIFICATION
       void glFrontFace( GLenum	mode )

       delim $$

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  en-
       able 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 fi-
       nally  back  to	its first vertex, moves	in a clockwise direction about
       the interior of the polygon.  The polygon's winding is said to be coun-
       terclockwise if the imaginary object following the same path moves in a
       counterclockwise	direction about	the interior of	the polygon.  glFront-
       Face specifies whether polygons with clockwise winding in window	 coor-
       dinates,	 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 execution	of glEnd.

ASSOCIATED GETS
       glGet with argument GL_FRONT_FACE

SEE ALSO
       glCullFace, glLightModel

								 GLFRONTFACE()

Want to link to this manual page? Use this URL:
<https://man.freebsd.org/cgi/man.cgi?query=glFrontFace&sektion=3&manpath=FreeBSD+Ports+15.0.quarterly>

home | help