The 2D shapes are all restricted to the xy plane. These shapes were introduced
in version 3.0, and so cannot be used in Vrml97 files. If these shapes are used
in the Immersive profile, it is necessary to specify the Geometry2D component.
In classic Vrml format, ...
A circle is specified simply by its radius. An Arc2D has a radius, and also a startAngle
and endAngle. All angles are specified in radians.
ArcClose2D
An ArcClose2D is similar to an Arc2D, having radius, startAngle and endAngle.
In addition, there is a closureType field that specifies the type of return
to the starting point. The two possible values for the closureType is PIE and CHORD.
Polypoint2D
The point field of a Polypoint2D contains a list of two dimensional points in
the xy plane.
Polyline2D
The point field of a Polyline2D contains a list of two dimensional points in
the xy plane. These points are connected to form a single polyline.
The Disk2D node has innerRadius and outerRadius fields. The innerRadius is less
than the outerRadius and specifies the size of the hole in the center. The
disk illustrated has innerRadius equal to 0. A texture is applied by pasting it
onto the square that bounds the disk.
The size field of a Rectangle2D is a two dimensional vector that specifies the
dimensions parallel to the x and y axes. A texture is stretched to fill the rectangle.
For the texture the first direction is along the longest side. This is the u axis for the
texture. The v axis is the other direction.
If the height is greater than the width, the y axis is the u axis for the texture.
The v axis for the texture will be along the x axis. To preserve the orientation of the
u and v axes, the texture faces toward the negative z axis.
If this texturing is not desired, it is necessary to create the rectangle with
an IndexedFaceSet and the TextureCoordinates should be specified directly.
The vertices field of the TriangleSet2D node contains a list of two dimensional points
in the xy plane. The first three points form the first triangle, the next three points
form the second triangle, etc. A texture is applied by finding the smallest rectangle that
contains this triangle set, and then applying the texture to this rectangle.
