endclo(3G)endclo(3G)NAME
bgnclo, endclo - delimit the vertices of a closed line
FORTRAN 77 SPECIFICATION
subroutine bgnclo
subroutine endcloPARAMETERS
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.
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endclo(3G)endclo(3G)
call bgnclo
call v3f(vert1)
call v3f(vert2)
call v3f(vert3)
call endcloSEE 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
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