The following paragraphs contain detailed descriptions of the subroutines included in the LONGLIB library for 3-d plotting. For added flexibility, two distinct families of 3-d plotting routines have been provided. One family is designed for plotting with hidden line removal; the other family is more flexible but does not perform hidden line removal. Both options assume that FRAME has already been called, i.e. the plot package is already opened. The 3-d routines call PLOT as output so that the 2-d plot origin, scaling, rotation, etc. are used in addition to any 3-d operations.
The nominal Z axis of the 3-d plot packages for plotted objects runs out of the screen. The X and Y axes are defined as before.
Two separate, independent 3-d packages exist. These are identified by the initialization routines used for each package. The hidden line removal package is INIT3DH and is a modification of the COSMIC hidden line code package (ARC-11446). The other is INIT3D. INIT3D does not perform any hidden line removal. These package differ not only in hidden line removal but also in speed of operation and memory requirements. The packages are completely independent. Only routines designed for a particular package will work with that package. It is possible to use both simultaneously.