bgntme(3G)

NAME
     bgntme, endtme - delimit the vertices of a triangle mesh

FORTRAN 77 SPECIFICATION
     subroutine bgntme

     subroutine endtme

PARAMETERS
     none

DESCRIPTION
     Vertices specified between bgntme and endtme are used to define a mesh of
     triangles.  The graphics pipe maintains two vertex registers.  The first
     and second vertices are loaded into the registers, but no triangle is
     drawn until the system executes the third vertex routine. Upon executing
     the third vertex routine, the system draws a triangle through the
     vertices, then replaces the older of the register vertices with the third
     vertex.

     For each new vertex routine, the system draws a triangle through the new
     vertex and the stored vertices, then (by default) replaces the older
     stored vertex with the new vertex.  If you want the system to replace the
     more recent of the stored vertices, call swaptm prior to calling v.

     Between bgntme and endtme you can issue the following Graphics Library
     routines:  c, color, cpack, lmbind, lmcolo, lmdef, n, RGBcol, swaptm, t,
     and v.  Use lmdef and lmbind only to respecify materials and their
     properties.

     If you want to use backfa, you should specify the vertices of the first
     triangle in counter-clockwise order.  All triangles in the mesh have the
     same rotation as the first triangle in a mesh so that backfacing works
     correctly.

     There is no limit to the number of vertices that can be specified between
     bgntme and endtme.

     By default triangle vertices are forced to the nearest pixel center prior
     to scan conversion.  Triangle accuracy is improved when this coercion is
     defeated with the subpix command.  Subpixel vertex positioning is
     especially important when triangles are scan converted with antialiasing
     enabled (see polysm).

     After endtme the current graphics position is undefined.

EXAMPLE
     For example, the code sequence:
          call bgntme
          call v3f(v0)
          call v3f(v1)
          call v3f(v2)
          call v3f(v3)
          call endtme


     draws two triangles, (v0,v1,v2) and (v3,v2,v1), while the code sequence:

          bgntme
          v3f(v0)
          v3f(v1)
          swaptm
          v3f(v2)
          v3f(v3)
          endtme


     draws two triangles, (v0,v1,v2) and (v0,v2,v3).  There is no limit to the
     number of times that swaptm can be called.

NOTE
     On Impact and Infinite Reality lmcolo cannot be called between bgntme and
     endtme

SEE ALSO
     backfa, c, concav, frontf, polymo, polysm, scrsub, setpat, shadem,
     subpix, swaptm, v