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Point fields display data positions as a ``cloud'' of points in space. The
data values themselves can be displayed as point color, point size, or point
shape. Points can be rendered very quickly with OpenGL. If the data is
static, display lists will give the best performance for most applications.
If the data is dynamically changing, try using vertex arrays to represent the
data. This also can simplify the application, since data value changes can
be accessed through arrays. Some data can be represented by changing the
point size, but this can be expensive on some implementations. It may also
help performance to sort points by size before rendering. This technique
is also used to render natural phenomena in Section 17.7.
If the number of points is small enough, and the implementation has high
enough performance, individual billboards can be used instead of OpenGL
points. This technique, as described in Section 6.10,
allows points of different shapes, and high quality appearance can be
achieved though alpha blending the polygon edges.