glgetclipplane(3g) [mojave man page]

GLGETCLIPPLANE(3G)														GLGETCLIPPLANE(3G)

NAME

       glGetClipPlane - return the coefficients of the specified clipping plane

C SPECIFICATION

       void glGetClipPlane( GLenum plane,
			    GLdouble *equation )

PARAMETERS

       plane	 Specifies  a  clipping  plane.  The number of clipping planes depends on the implementation, but at least six clipping planes are
		 supported.  They are identified by symbolic names of the form GL_CLIP_PLANEi where 0 <=  i  < GL_MAX_CLIP_PLANES.

       equation  Returns four double-precision values that are the coefficients of the plane equation of plane in eye  coordinates.   The  initial
		 value is (0, 0, 0, 0).

DESCRIPTION

       glGetClipPlane returns in equation the four coefficients of the plane equation for plane.

NOTES

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

       If an error is generated, no change is made to the contents of equation.

ERRORS

       GL_INVALID_ENUM is generated if plane is not an accepted value.

       GL_INVALID_OPERATION is generated if glGetClipPlane is executed between the execution of glBegin and the corresponding execution of glEnd.

SEE ALSO

       glClipPlane

																GLGETCLIPPLANE(3G)

GLCLIPPLANE(3G) 														   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  equa-
		 tion.

DESCRIPTION

       Geometry  is  always  clipped  against the boundaries of a six-plane frustum in x, y, and z.  glClipPlane allows the specification of addi-
       tional planes, not necessarily perpendicular to the x, y, or z axis, against which all geometry is clipped.  To determine the maximum  num-
       ber 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 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

       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

																   GLCLIPPLANE(3G)