NAME    [Toc]    [Back]

       glClipPlane  -  specify a plane against which all geometry
       is clipped

SYNOPSIS    [Toc]    [Back]

       void glClipPlane(
               GLenum plane,
               const GLdouble *equation );

PARAMETERS    [Toc]    [Back]

       Specifies which clipping plane is being  positioned.  Symbolic
  names  of  the  form  GL_CLIP_PLANEi, where i is an
       integer between 0 and GL_MAX_CLIP_PLANES-1, are  accepted.
       Specifies the address of an array of four double-precision
       floating-point values. These values are interpreted  as  a
       plane equation.

DESCRIPTION    [Toc]    [Back]

       Geometry  is  always  clipped  against the boundaries of a
       six-plane frustum in x, y, and z.  glClipPlane allows  the
       specification  of  additional planes, not necessarily perpendicular
 to the x, y, or z axis, against which all geometry
  is clipped. To determine the maximum number of additional
 clipping planes, call glGetIntegerv() with argument
       GL_MAX_CLIP_PLANES.  All  implementations support at least
       six such clipping planes.  Because the resulting  clipping
       region  is the intersection of the defined half-spaces, it
       is always convex.

       glClipPlane() specifies a half-space using  a  four-component
  plane  equation. When glClipPlane() is called, equation
 is transformed by the inverse of the modelview matrix
       and  stored  in  the resulting eye coordinates. Subsequent
       changes to the modelview matrix  have  no  effect  on  the
       stored  plane-equation  components.  If the dot product of
       the eye coordinates of a  vertex  with  the  stored  plane
       equation  components is positive or zero, the vertex is in
       with respect to that clipping plane. Otherwise, it is out.

       To enable and disable clipping planes, call glEnable() and
       glDisable() with the argument GL_CLIP_PLANEi, where  i  is
       the plane number.

       All  clipping planes are initially defined as (0, 0, 0, 0)
       in eye coordinates and are disabled.

NOTES    [Toc]    [Back]

       It   is   always   the   case   that   GL_CLIP_PLANEi    =
       GL_CLIP_PLANE0+i.

ERRORS    [Toc]    [Back]

       GL_INVALID_ENUM  is  generated if plane is not an accepted
       value.

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

ASSOCIATED GETS    [Toc]    [Back]

       glGetClipPlane()
       glIsEnabled() with argument GL_CLIP_PLANEi

SEE ALSO    [Toc]    [Back]

       glEnable(3)



                                                  glClipPlane(3G)