endclo(3G)

NAME
     bgnclo, endclo - delimit the vertices of a closed line

FORTRAN 77 SPECIFICATION
     subroutine bgnclo

     subroutine endclo

PARAMETERS
     none

DESCRIPTION
     bgnclo marks the start of a group of vertex routines that you want
     interpreted as points on a closed line.  Use endclo to mark the end of
     the vertex routines that are part of the closed line.

     A closed line draws a line segment from one vertex on the list to the
     next vertex on the list. When the system reaches the end of the vertex
     list, it draws a line that connects the last vertex to the first vertex.
     All segments use the current linestyle, which is reset prior to the first
     segment and continues through subsequent segments.  To specify a vertex,
     use the v routine.

     Between bgnclo and endclo, you can issue only the following Graphics
     Library routines: c, color, cpack, lmbind, lmcolo, lmdef, n, RGBcol, t,
     and v.  Within a closed line, you should use lmdef and lmbind only to
     respecify materials and their properties.  If the color changes between a
     pair of vertices, the color of the line segment will be constant if the
     current shading model is FLAT and interpolated if the current shading
     model is GOURAU.  In color map mode, the colors vary through the color
     map; to get reasonable results, the color map should contain a ramp.

     There is no limit to the number of vertices that can be specified between
     bgnclo and endclo.  After endclo, the system draws a line from the final
     vertex back to the initial vertex, and the current graphics position is
     left undefined.

     By default, line vertices are forced to the nearest pixel center prior to
     scan conversion.  Line accuracy is improved when this coercion is
     defeated with the subpix command.  Subpixel vertex positioning is
     especially important when lines are scan-converted with antialiasing
     enabled (see linesm).

     bgnclo/endclo are the same as bgnlin/endlin, except they connect the last
     vertex to the first.

EXAMPLE
     The code fragment below draws the outline of a triangle. Lines use the
     current linestyle, which is reset prior to the first vertex and continues
     through all subsequent vertices.
          call bgnclo
          call v3f(vert1)
          call v3f(vert2)
          call v3f(vert3)
          call endclo


SEE ALSO
     bgnlin, c, linesm, linewi, lsrepe, scrsub, setlin, shadem, subpix, v

BUGS
     On the IRIS-4D B and G models, and on the Personal Iris without Turbo
     Graphics, if the color changes between a pair of vertices, the color of
     the line segment will be constant regardless of the current shading
     model.

     On the IRIS-4D GT and GTX models, if the color changes between a pair of
     vertices, the color of the line segment will be interpolated regardless
     of the current shading model.

     On the IRIS-4D B and G models, the linestyle is reset at the start of
     each segment, rather than only at the start of the first segment.

     On Impact and Infinite Reality lmcolo cannot be called between bgnclo and
     endclo