glClipPlane function

Article
12/11/2020

The glClipPlane function specifies a plane against which all geometry is clipped.

Syntax

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

Parameters

plane: The clipping plane that 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: The address of an array of four double-precision floating-point values. These values are interpreted as a plane equation.

Return value

This function does not return a value.

Error codes

The following error codes can be retrieved by the glGetError function.

Name	Meaning
GL_INVALID_ENUM	plane was not an accepted value.
GL_INVALID_OPERATION	The function was called between a call to glBegin and the corresponding call to glEnd.

Remarks

Geometry is always clipped against the boundaries of a six-plane frustum in x, y, and z. The glClipPlane function allows the specification of additional planes, not necessarily perpendicular to the x-axis, y-axis, 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.

The glClipPlane function specifies a half-space using a four-component plane equation. When you call glClipPlane,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.

Use the glEnable and glDisable functions to enable and disable clipping planes. Call clipping planes 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.

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

The following functions retrieve information related to glClipPlane:

glGetClipPlane

glIsEnabled with argument GL_CLIP_PLANE i

Requirements

Requirement	Value
Minimum supported client	Windows 2000 Professional [desktop apps only]
Minimum supported server	Windows 2000 Server [desktop apps only]
Header	Gl.h
Library	Opengl32.lib
DLL	Opengl32.dll