glClipPlane(3G)						       glClipPlane(3G)

NAME
       glClipPlane - specify a plane against which all geometry is clipped

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

PARAMETERS
       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 inter‐
       preted 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 addi‐
       tional	 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 coordi‐
       nates of a vertex with the stored plane equation components is positive
       or zero, the vertex is in with respect to that clipping	plane.	Other‐
       wise, 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_PLANEi = 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(3)

							       glClipPlane(3G)

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