fglClipPlane(3G) OpenGL Reference fglClipPlane(3G)NAMEfglClipPlane - specify a plane against which all geometry is clipped
FORTRAN SPECIFICATION
SUBROUTINE fglClipPlane( INTEGER*4 plane,
CHARACTER*8 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
equation.
DESCRIPTION
Geometry is always clipped against the boundaries of a six-plane frustum
in x, y, and z. fglClipPlane allows the specification 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 clipping planes, call fglGetIntegerv 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.
fglClipPlane specifies a half-space using a four-component plane
equation. When fglClipPlane 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 fglEnable and fglDisable 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 fglClipPlane is executed between the
execution of fglBegin and the corresponding execution of fglEnd.
Page 1
fglClipPlane(3G) OpenGL Reference fglClipPlane(3G)ASSOCIATED GETS
fglGetClipPlane
fglIsEnabled with argument GL_CLIP_PLANEi
SEE ALSO
fglEnable
Page 2
