OpenGL man pages
## glClipPlane.3gl

## 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_PLANE*i*, 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_PLANE*i*, 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.

## Associated Gets

glGetClipPlane
glIsEnabled with argument GL_CLIP_PLANE*i*

## See Also

glEnable

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Last Edited: *
Fri Dec 6 11:18:03 EST 1996
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*AFV*

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