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GLE extrusion, sweep and tubing library
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<title>gleJoinStyle Documentation</title>
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<h1>gleJoinStyle Documentation</h1>
<img src="cut.gif"> <img src="round.gif"> <br>
<img src="angle.gif"> <img src="raw.gif">
<h2>Subroutine Descriptions</h2>
<dl>
<dt><pre><b>int gleGetJoinStyle (void);
void gleSetJoinStyle (int style); /* bitwise OR of flags */
</b></pre>
<dd> Query and Set the join style flags. This word is a bitwise OR of the flags
described below.
<h3> Extrusion Join Styles </h3>
<dl>
<dt><b>TUBE_JN_RAW</b>
<dd>Draw polycylinders, polycones, extrusions, <i>etc.</i>
with no special treatment of the
extrusion ends.
<p>
<dt><b> TUBE_JN_ANGLE </b>
<dd>Draw polycylinders, polycones, extrusions, <i>etc.</i>
by extending the different segments until they
butt into each other with an angular style.
<p>
<dt><b> TUBE_JN_CUT </b>
<dd>Draw polycylinders, polycones, extrusions, <i>etc.</i>
by joining together the different segments and slicing off
the joint at half the angle between the segments. A cap is drawn.
Note that the slicing plane runs through the origin of the contour
coordinate system. Thus, the amount of slice can be varied by offsetting
the contour with respect to the origin.
<p>
Note that when two segments meet at a shallow angle, the cut join
style will potentially shave off a whole lot of the contour,
leading to "surprising" results...
<p>
<dt><b> TUBE_JN_ROUND </b>
<dd> Joints will be rounded. Strictly speaking, the part of the joint
above the origin will be rounded. The part below the origin will come
together in an angular join.
<p>
<dt><b> TUBE_JN_MASK </b>
<dd> Mask bits. This can be used to mask off the bit field that defines
the join style.
</dl>
<img src="offround.gif">
<img src="endcap.gif">
<h3> End Caps </h3>
<dl>
<dt><b> TUBE_JN_CAP </b>
<dd> If this is set, a cap will be drawn at each end of the extrusion.
<p>
</dl>
<img src="facenorm.gif"><img src="edgenorm.gif">
<img src="facesweep.gif"><img src="edgesweep.gif">
<img src="facet.gif"><img src="edge.gif">
<h3>Automatic Normal Vector Generation </h3>
<dl>
<dt><b> TUBE_NORM_FACET </b>
<dd> A normal vector is generated per facet. Useful for having an
extrusion have a "faceted" look, such as when extruding a square -- each
of the four sides of the square will look flat.
<p>
<dt><b> TUBE_NORM_EDGE </b>
<dd> Normal vectors are generated so that they lie along edges. Useful
for making angular things look rounded under lighting. For example,
when extruding a hexagon and using this flag, the hexagonal
extrusion will look (more like a) smooth perfectly round cylinder,
rather than a six-sided shape.
<p>
<dt><b> TUBE_NORM_PATH_EDGE </b>
<dd> Normal vectors are generated so that they both lie on edges, and so
that they interpolate between neighboring segments. Useful for
drawing "spaghetti" -- extrusions that follow a spline path.
Because the spline path must be "tessellated" into small straight
segments, each segment will look straight unless this flag is set.
<p>
<dt><b> TUBE_NORM_MASK </b>
<dd> A mask useful for masking out the "norm" bits.
</dl>
<img src="opencontour.gif">
<h3>Closed or Open Contours </h3>
<dl>
<dt><b> TUBE_CONTOUR_CLOSED </b>
<dd> If this bit is set, the contour will be treated as a "closed"
contour, where the last point connects back up to the first.
It is useful to set this flag when drawing closed shapes (such as
extruded cylinders, star-shapes, I-Beams, <i>etc.</i>) When drawing open
extrusions (<i>e.g.</i> corrugated sheet metal), you DON'T want to set this
flag.
<p>
</dl>
</dl>
<h2> The End </h2>
<address>
Originally developed by Linas Vepstas in 1991<br>
Version 2.0 -- port to OpenGL, 1993 <br>
Version 2.1 -- assorted touch-ups, cleanups, <i>etc.</i><br>
Version 2.1.1 -- additional demos <br>
</address>
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