MirBSD manpage: glClipPlane(3)


GLCLIPPLANE(3G)     UNIX Programmer's Manual      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 posi-
               tioned. 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 specif-
     ication 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 clip-
     ping 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 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. 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.

MirBSD #10-current     Printed 2021-12-07                       1

GLCLIPPLANE(3G)     UNIX Programmer's Manual      GLCLIPPLANE(3G)

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 exe-
     cution of glEnd.

ASSOCIATED GETS

     glGetClipPlane
     glIsEnabled with argument GL_CLIP_PLANEi

SEE ALSO

     glEnable(3G)

MirBSD #10-current     Printed 2021-12-07                       2

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