endclosedline(3G)					     endclosedline(3G)

NAME    [Toc]    [Back]

     bgnclosedline, endclosedline - delimit the	vertices of a closed line

C SPECIFICATION    [Toc]    [Back]

     void bgnclosedline()

     void endclosedline()

PARAMETERS    [Toc]    [Back]

     none

DESCRIPTION    [Toc]    [Back]

     bgnclosedline marks the start of a	group of vertex	routines that you want
     interpreted as points on a	closed line.  Use endclosedline	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 bgnclosedline and endclosedline, you can issue only the following
     Graphics Library routines:	c, color, cpack, lmbind, lmcolor, lmdef, n,
     RGBcolor, 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 GOURAUD.	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
     bgnclosedline and endclosedline.  After endclosedline, 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 subpixel	command.  Subpixel vertex positioning is
     especially	important when lines are scan-converted	with antialiasing
     enabled (see linesmooth).

     bgnclosedline/endclosedline are the same as bgnline/endline, except they
     connect the last vertex to	the first.

EXAMPLE    [Toc]    [Back]

     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.




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endclosedline(3G)					     endclosedline(3G)



	  bgnclosedline();
	  v3f(vert1);
	  v3f(vert2);
	  v3f(vert3);
	  endclosedline();

SEE ALSO    [Toc]    [Back]

     bgnline, c, linesmooth, linewidth,	lsrepeat, scrsubdivide,	setlinestyle,
     shademodel, subpixel, v

BUGS    [Toc]    [Back]

     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 lmcolor cannot be called between
     bgnclosedline and endclosedline


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