16.1.4.1 Point Fields

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.