Section: Misc. Reference Manual Pages (3G)
- specify a plane against which all geometry is clipped
const GLdouble *equation )
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$^-^1$,
Specifies the address of an array of four double-precision floating-point values.
These values are interpreted as a plane equation.
Geometry is always clipped against the boundaries of a six-plane frustum
, and z
allows the specification of additional planes,
not necessarily perpendicular to the x
, or z
against which all geometry is clipped.
To determine the maximum number of additional clipping planes, call
with argument GL_MAX_CLIP_PLANES
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 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
where i is the plane number.
All clipping planes are initially defined as (0, 0, 0, 0) in eye coordinates
and are disabled.
It is always the case that GL_CLIP_PLANE
$i$ = GL_CLIP_PLANE0
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.
with argument GL_CLIP_PLANEi