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<h4 class="subsection">4.2.6 VECT Files</h4>
<p>The conventional suffix for <code>VECT</code> files is <samp><span class="file">.vect</span></samp>.
<p>Syntax:
<pre class="example"> [4]VECT
<var>NPolylines</var> <var>NVertices</var> <var>NColors</var>
<var>Nv[0]</var> ... <var>Nv[NPolylines-1]</var> # number of vertices
# in each polyline
<var>Nc[0]</var> ... <var>Nc[NPolylines-1]</var> # number of colors supplied
# in each polyline
<var>Vert[0]</var> ... <var>Vert[NVertices-1]</var> # All the vertices
# (3*NVertices floats)
<var>Color[0]</var> ... <var>Color[NColors-1]</var> # All the colors
# (4*NColors floats, RGBA)
</pre>
<p><code>VECT</code> objects represent lists of polylines (strings of connected
line segments, possibly closed). A degenerate polyline can be used to
represent a point.
<p>A <code>VECT</code> file begins with the key word <code>VECT</code> or <code>4VECT</code>
and three integers: <var>NLines</var>, <var>NVertices</var>, and <var>NColors</var>.
Here <var>NLines</var> is the number of polylines in the file,
<var>NVertices</var> the total number of vertices, and <var>NColors</var> the
number of colors as explained below.
<p>Next come <var>NLines</var> <b>16-bit</b> integers
<div align="center"><var>Nv[0]</var> <var>Nv[1]</var> <var>Nv[2]</var> <small class="dots">...</small> <var>Nv[NLines-1]</var></div>
<p>giving the number of vertices in each polyline. A negative number
indicates a closed polyline; 1 denotes a single-pixel point. The sum
(of absolute values) of the <var>Nv[i]</var> must equal <var>NVertices</var>.
<p>Next come <var>NLines</var> more <b>16-bit</b> integers <var>Nc[i]</var>: the number
of colors in each polyline. Normally one of three values:
<dl>
<dt>0<dd>No color is specified for this polyline. It's drawn in the same color
as the previous polyline.
<br><dt>1<dd>A single color is specified. The entire polyline is drawn in that
color.
<br><dt>abs(<var>Nv[i]</var>)<dd>Each vertex has a color. Either each segment is drawn in the
corresponding color, or the colors are smoothly interpolated along the
line segments, depending on the implementation.
</dl>
<p>Next come <var>NVertices</var> groups of 3 or 4 floating-point numbers: the
coordinates of all the vertices. If the keyword is <var>4VECT</var> then
there are 4 values per vertex. The first abs(<var>Nv[0]</var>) of them form
the first polyline, the next abs(<var>Nv[1]</var>) form the second and so on.
<p>Finally <var>NColors</var> groups of 4 floating-point numbers give red,
green, blue and alpha (opacity) values. The first <var>Nc[0]</var> of them
apply to the first polyline, and so on.
<p>A <var>VECT BINARY</var> format is accepted; see <a href="Binary-format.html#Binary-format">Binary format</a>. The
binary format exactly follows the ASCII format, with 32-bit Big-Endian
integers where ordinary integer numbers appear, and with <b>16-bit</b>
Big-Endian integers where 16-bit integers appear; 32-bit Big-Endian
floats where real values appear. <b>BIG FAT NOTE:</b> The vertex counts
<var>Nv[i]</var> and the color counts <var>Nc[i]</var> are <b>16-bit</b> Big-Endian
integers.
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