!=====================================================================
! NGTD: Tdpack, A Three-Dimensional Plotting Utility
!=====================================================================
!
! TDPACK is a collection of routines for projecting objects from a
! 3-dimensional coordinate system having U, V, and W axes to a
! 2-dimensional projection plane having X and Y axes and/or for
! drawing the projections of those objects. This can be referred to
! somewhat loosely as "drawing objects in three dimensions".
!
! ~~~~~~~~~~~~~~~~~~
! Parameter Routines
! ~~~~~~~~~~~~~~~~~~
!
! NG_TDRSET - reset all internal parameters
!
! NG_TDSETR - set the real value of an internal parameter
! NG_TDSETI - set the integer value of an internal parameter
!
! NG_TDGETR - get the real value of an internal parameter
! NG_TDGETI - get the integer value of an internal parameter
!
! ~~~~~~~~~~~~~~~~~~
! Rendering Routines
! ~~~~~~~~~~~~~~~~~~
!
! NG_TDSTRS - define a specified rendering style
! NG_TDGTRS - get the definition of a specified rendering style
!
! ~~~~~~~~~~~~~~
! Color Routines
! ~~~~~~~~~~~~~~
!
! NG_TDCLRS - define basic and shading colors
!
! ~~~~~~~~~~~~~~~~~~~~~~~
! Initialization Routines
! ~~~~~~~~~~~~~~~~~~~~~~~
!
! NG_TDINIT - define eye position, line of sight, up direction, and stereo flag
!
! ~~~~~~~~~~~~~~~~~~~~~
! Transforming Routines
! ~~~~~~~~~~~~~~~~~~~~~
!
! NG_TDPARA - define the reference parallelogram
!
! NG_TDPRPT - from 3-space to the projection plane
! NG_TDPRPA - from the plane of the reference parallelogram to the projection plane
! NG_TDPRPI - from the projection plane to the plane of the reference parallelogram
!
! ~~~~~~~~~~~~~~~~
! Surface Routines
! ~~~~~~~~~~~~~~~~
!
! NG_TDSTRI - add triangles defining a "surface" to a triangle list
! NG_TDITRI - add triangles defining an "isosurface" to a triangle list
! NG_TDTTRI - add triangles defining a "trajectory" to a triangle list
! NG_TDMTRI - add triangles defining a 3D marker to a triangle
!
! NG_TDCTRI - cut the triangles in a triangle list
!
! NG_TDOTRI - order the triangles in a triangle list for proper renderi
!
! ~~~~~~~~~~~~~~~~
! Drawing Routines
! ~~~~~~~~~~~~~~~~
!
! NG_TDDTRI - draw triangles defined by a triangle list
!
! NG_TDGRDS - draw the grids on all the faces of a box in 3-space
! NG_TDGRID - draw the grid on a particular face of a box in 3-space
!
! NG_TDLBLS - draw labels for all faces of a box in 3-space
! NG_TDLBLA - draw labels for a particular face of a box in 3-space
! NG_TDPLCH - draw characters in the plane of the reference parallelogram
!
! NG_TDCURV - draw the projection of a solid curve in 3-space
! NG_TDCUDP - draw the projection of a dashed curve in 3-space
!
! NG_TDLINE - draw the projection of a solid line in 3-space
! NG_TDLNDP - draw the projection of a dashed line in 3-space
!
! NG_TDLNPA - draw the projection of a solid line in the plane of the reference parallelogram
! NG_TDLPDP - draw the projection of a dashed line in the plane of the reference parallelogram
!
! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
! Simplified-Interface Routines
! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
!
! NG_TDEZ2D - simplified interface for drawing a surface
!
! NG_TDEZ3D - simplified interface for drawing an isosurface
!
!---------------------------------------
!
! Note: CNCARG add a "optional dummy subprogram arguments", TDLBLP,
!       to following TDPACK routines.
!
!  NG_TDLBLS( UMIN, VMIN, WMIN, UMAX, VMAX, WMAX, UNLB, VNLB, WNLB, &
!             UILB, VILB, WILB, IPCK, TDLBLP)
!
!  NG_TDLBLA( IAXS, ILBL, NLBL, XAT0, XAT1, YAT0, YAT1, ANGD, TDLBLP )
!
! Note: CNCARG remove the first argument "IWID" from routine NG_TDCLRS
!
!=====================================================================
!
! default colors. indices 0 to 7, in tdpack
!
!   color 0 - background (white or black decided by ibow of NG_tdclrs)
!   color 1 - foreground (black or white decided by ibow of NG_tdclrs)
!   color 2 - red
!   color 3 - green
!   color 4 - blue
!   color 5 - cyan
!   color 6 - magenta
!   color 7 - yellow
!
!=====================================================================
! Refer "ncar menu" for interfacing TDPACK in detail
!=====================================================================