glClipPlane(3G)		       OpenGL Reference		       glClipPlane(3G)



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


C SPECIFICATION
     void glClipPlane( GLenum plane,
		       const GLdouble *equation	)


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 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.  Up	to GL_MAX_CLIP_PLANES planes can be
     specified,	where GL_MAX_CLIP_PLANES is at least six in all
     implementations.  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.

     Clipping planes are enabled and disabled with glEnable and	glDisable, and
     called with the argument GL_CLIP_PLANEi, where i is the plane number.

     By	default, all clipping planes are defined as (0,0,0,0) in eye
     coordinates 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.





									Page 1






glClipPlane(3G)		       OpenGL Reference		       glClipPlane(3G)



ASSOCIATED GETS
     glGetClipPlane
     glIsEnabled with argument GL_CLIP_PLANEi


SEE ALSO
     glEnable
















































									Page 2