glClipPlane(3)

NAME

       glClipPlane - specify a plane against which all geometry is clipped

C SPECIFICATION

       void glClipPlane( GLenum plane,
                         const GLdouble *equation )

       delim $$

PARAMETERS

       plane     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.

       equation  Specifies  the  address  of an array of four double-precision
                 floating-point values.  These values  are  interpreted  as  a
                 plane equation.

DESCRIPTION

       Geometry  is always clipped against the boundaries of a six-plane frus-
       tum 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 clip-
       ping 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  equa-
       tion.   When  glClipPlane  is  called,  equation  is transformed by the
       inverse of the modelview matrix and stored in the resulting eye coordi-
       nates.   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  coor-
       dinates and are disabled.

NOTES

       It is always the case that GL_CLIP_PLANE$i$ = GL_CLIP_PLANE0$~+~i$.

ERRORS

       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

       glGetClipPlane
       glIsEnabled with argument GL_CLIP_PLANEi

SEE ALSO

       glEnable(3G)

                                                               GLCLIPPLANE(3G)