disk3D
Creates a new disk in ℝ³.
Syntax

disk3D([a[, f[, d[, α]]]])

a
is a threedimensional real vector 
f
is a threedimensional real vector 
d
is a threedimensional real vector 
α
is a real number

Description
disk3D()
creates a circular disk of radius 1 centred at the origin with normal direction ❨0, 0, 1❩
.
disk3D(a, f, d, α)
translates the disk by a
, scales it by diag(f)
, aligns its normal with d
, and rotates it an amount α
about its (normal) axis.
Since a disk is flat, the third component of f
should be unity. Unless the two first components of f
coincide, the resulting object will be a noncircular elliptic disk.
Hence,

a
specifies the position of the disk’s centre. 
f = (s, t, 1)
specifies the halfaxis lengthss
andt
of the (elliptic) disk. 
d
specifies the normal direction of the disk. 
α
specifies the rotation of the disk about its (normal) axis.
If omitted, a
defaults to ❨0, 0, 0❩
, f
to ❨1, 1, 1❩
, d
to ❨0, 0, 1❩
, and α
to 0
.
The object is shown in the current scene and a reference to the object is returned.
The AdjustVisual
function can be used to adjust the appearance of the disk. See Visual settings for a list of applicable settings.
Examples
disk3D()