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<div class="section" id="module-gl">
<h1>38.8. <tt class="xref docutils literal"><span class="pre">gl</span></tt> — <em>Graphics Library</em> interface<a class="headerlink" href="#module-gl" title="Permalink to this headline">¶</a></h1>
<p><em>Platforms: </em>IRIX</p>
<p class="deprecated">
<span class="versionmodified">Deprecated since version 2.6: </span>The <tt class="xref docutils literal"><span class="pre">gl</span></tt> module has been deprecated for removal in Python 3.0.</p>
<p>This module provides access to the Silicon Graphics <em>Graphics Library</em>. It is
available only on Silicon Graphics machines.</p>
<div class="admonition warning">
<p class="first admonition-title">Warning</p>
<p class="last">Some illegal calls to the GL library cause the Python interpreter to dump
core. In particular, the use of most GL calls is unsafe before the first
window is opened.</p>
</div>
<p>The module is too large to document here in its entirety, but the following
should help you to get started. The parameter conventions for the C functions
are translated to Python as follows:</p>
<ul>
<li><p class="first">All (short, long, unsigned) int values are represented by Python integers.</p>
</li>
<li><p class="first">All float and double values are represented by Python floating point numbers.
In most cases, Python integers are also allowed.</p>
</li>
<li><p class="first">All arrays are represented by one-dimensional Python lists. In most cases,
tuples are also allowed.</p>
</li>
<li><p class="first">All string and character arguments are represented by Python strings, for
instance, <tt class="docutils literal"><span class="pre">winopen('Hi</span> <span class="pre">There!')</span></tt> and <tt class="docutils literal"><span class="pre">rotate(900,</span> <span class="pre">'z')</span></tt>.</p>
</li>
<li><p class="first">All (short, long, unsigned) integer arguments or return values that are only
used to specify the length of an array argument are omitted. For example, the C
call</p>
<div class="highlight-python"><div class="highlight"><pre><span class="n">lmdef</span><span class="p">(</span><span class="n">deftype</span><span class="p">,</span> <span class="n">index</span><span class="p">,</span> <span class="n">np</span><span class="p">,</span> <span class="n">props</span><span class="p">)</span>
</pre></div>
</div>
<p>is translated to Python as</p>
<div class="highlight-python"><div class="highlight"><pre><span class="n">lmdef</span><span class="p">(</span><span class="n">deftype</span><span class="p">,</span> <span class="n">index</span><span class="p">,</span> <span class="n">props</span><span class="p">)</span>
</pre></div>
</div>
</li>
<li><p class="first">Output arguments are omitted from the argument list; they are transmitted as
function return values instead. If more than one value must be returned, the
return value is a tuple. If the C function has both a regular return value (that
is not omitted because of the previous rule) and an output argument, the return
value comes first in the tuple. Examples: the C call</p>
<div class="highlight-python"><pre>getmcolor(i, &red, &green, &blue)</pre>
</div>
<p>is translated to Python as</p>
<div class="highlight-python"><div class="highlight"><pre><span class="n">red</span><span class="p">,</span> <span class="n">green</span><span class="p">,</span> <span class="n">blue</span> <span class="o">=</span> <span class="n">getmcolor</span><span class="p">(</span><span class="n">i</span><span class="p">)</span>
</pre></div>
</div>
</li>
</ul>
<p>The following functions are non-standard or have special argument conventions:</p>
<dl class="function">
<dt id="gl.varray">
<tt class="descclassname">gl.</tt><tt class="descname">varray</tt><big>(</big><em>argument</em><big>)</big><a class="headerlink" href="#gl.varray" title="Permalink to this definition">¶</a></dt>
<dd>Equivalent to but faster than a number of <tt class="docutils literal"><span class="pre">v3d()</span></tt> calls. The <em>argument</em> is a
list (or tuple) of points. Each point must be a tuple of coordinates <tt class="docutils literal"><span class="pre">(x,</span> <span class="pre">y,</span>
<span class="pre">z)</span></tt> or <tt class="docutils literal"><span class="pre">(x,</span> <span class="pre">y)</span></tt>. The points may be 2- or 3-dimensional but must all have the
same dimension. Float and int values may be mixed however. The points are always
converted to 3D double precision points by assuming <tt class="docutils literal"><span class="pre">z</span> <span class="pre">=</span> <span class="pre">0.0</span></tt> if necessary (as
indicated in the man page), and for each point <tt class="docutils literal"><span class="pre">v3d()</span></tt> is called.</dd></dl>
<dl class="function">
<dt id="gl.nvarray">
<tt class="descclassname">gl.</tt><tt class="descname">nvarray</tt><big>(</big><big>)</big><a class="headerlink" href="#gl.nvarray" title="Permalink to this definition">¶</a></dt>
<dd>Equivalent to but faster than a number of <tt class="docutils literal"><span class="pre">n3f</span></tt> and <tt class="docutils literal"><span class="pre">v3f</span></tt> calls. The
argument is an array (list or tuple) of pairs of normals and points. Each pair
is a tuple of a point and a normal for that point. Each point or normal must be
a tuple of coordinates <tt class="docutils literal"><span class="pre">(x,</span> <span class="pre">y,</span> <span class="pre">z)</span></tt>. Three coordinates must be given. Float and
int values may be mixed. For each pair, <tt class="docutils literal"><span class="pre">n3f()</span></tt> is called for the normal, and
then <tt class="docutils literal"><span class="pre">v3f()</span></tt> is called for the point.</dd></dl>
<dl class="function">
<dt id="gl.vnarray">
<tt class="descclassname">gl.</tt><tt class="descname">vnarray</tt><big>(</big><big>)</big><a class="headerlink" href="#gl.vnarray" title="Permalink to this definition">¶</a></dt>
<dd>Similar to <tt class="docutils literal"><span class="pre">nvarray()</span></tt> but the pairs have the point first and the normal
second.</dd></dl>
<dl class="function">
<dt id="gl.nurbssurface">
<tt class="descclassname">gl.</tt><tt class="descname">nurbssurface</tt><big>(</big><em>s_k</em>, <em>t_k</em>, <em>ctl</em>, <em>s_ord</em>, <em>t_ord</em>, <em>type</em><big>)</big><a class="headerlink" href="#gl.nurbssurface" title="Permalink to this definition">¶</a></dt>
<dd>Defines a nurbs surface. The dimensions of <tt class="docutils literal"><span class="pre">ctl[][]</span></tt> are computed as follows:
<tt class="docutils literal"><span class="pre">[len(s_k)</span> <span class="pre">-</span> <span class="pre">s_ord]</span></tt>, <tt class="docutils literal"><span class="pre">[len(t_k)</span> <span class="pre">-</span> <span class="pre">t_ord]</span></tt>.</dd></dl>
<dl class="function">
<dt id="gl.nurbscurve">
<tt class="descclassname">gl.</tt><tt class="descname">nurbscurve</tt><big>(</big><em>knots</em>, <em>ctlpoints</em>, <em>order</em>, <em>type</em><big>)</big><a class="headerlink" href="#gl.nurbscurve" title="Permalink to this definition">¶</a></dt>
<dd>Defines a nurbs curve. The length of ctlpoints is <tt class="docutils literal"><span class="pre">len(knots)</span> <span class="pre">-</span> <span class="pre">order</span></tt>.</dd></dl>
<dl class="function">
<dt id="gl.pwlcurve">
<tt class="descclassname">gl.</tt><tt class="descname">pwlcurve</tt><big>(</big><em>points</em>, <em>type</em><big>)</big><a class="headerlink" href="#gl.pwlcurve" title="Permalink to this definition">¶</a></dt>
<dd>Defines a piecewise-linear curve. <em>points</em> is a list of points. <em>type</em> must be
<tt class="docutils literal"><span class="pre">N_ST</span></tt>.</dd></dl>
<dl class="function">
<dt id="gl.pick">
<tt class="descclassname">gl.</tt><tt class="descname">pick</tt><big>(</big><em>n</em><big>)</big><a class="headerlink" href="#gl.pick" title="Permalink to this definition">¶</a></dt>
<dt id="gl.select">
<tt class="descclassname">gl.</tt><tt class="descname">select</tt><big>(</big><em>n</em><big>)</big><a class="headerlink" href="#gl.select" title="Permalink to this definition">¶</a></dt>
<dd>The only argument to these functions specifies the desired size of the pick or
select buffer.</dd></dl>
<dl class="function">
<dt id="gl.endpick">
<tt class="descclassname">gl.</tt><tt class="descname">endpick</tt><big>(</big><big>)</big><a class="headerlink" href="#gl.endpick" title="Permalink to this definition">¶</a></dt>
<dt id="gl.endselect">
<tt class="descclassname">gl.</tt><tt class="descname">endselect</tt><big>(</big><big>)</big><a class="headerlink" href="#gl.endselect" title="Permalink to this definition">¶</a></dt>
<dd>These functions have no arguments. They return a list of integers representing
the used part of the pick/select buffer. No method is provided to detect buffer
overrun.</dd></dl>
<p>Here is a tiny but complete example GL program in Python:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="kn">import</span> <span class="nn">gl</span><span class="o">,</span> <span class="nn">GL</span><span class="o">,</span> <span class="nn">time</span>
<span class="k">def</span> <span class="nf">main</span><span class="p">():</span>
<span class="n">gl</span><span class="o">.</span><span class="n">foreground</span><span class="p">()</span>
<span class="n">gl</span><span class="o">.</span><span class="n">prefposition</span><span class="p">(</span><span class="mi">500</span><span class="p">,</span> <span class="mi">900</span><span class="p">,</span> <span class="mi">500</span><span class="p">,</span> <span class="mi">900</span><span class="p">)</span>
<span class="n">w</span> <span class="o">=</span> <span class="n">gl</span><span class="o">.</span><span class="n">winopen</span><span class="p">(</span><span class="s">'CrissCross'</span><span class="p">)</span>
<span class="n">gl</span><span class="o">.</span><span class="n">ortho2</span><span class="p">(</span><span class="mf">0.0</span><span class="p">,</span> <span class="mf">400.0</span><span class="p">,</span> <span class="mf">0.0</span><span class="p">,</span> <span class="mf">400.0</span><span class="p">)</span>
<span class="n">gl</span><span class="o">.</span><span class="n">color</span><span class="p">(</span><span class="n">GL</span><span class="o">.</span><span class="n">WHITE</span><span class="p">)</span>
<span class="n">gl</span><span class="o">.</span><span class="n">clear</span><span class="p">()</span>
<span class="n">gl</span><span class="o">.</span><span class="n">color</span><span class="p">(</span><span class="n">GL</span><span class="o">.</span><span class="n">RED</span><span class="p">)</span>
<span class="n">gl</span><span class="o">.</span><span class="n">bgnline</span><span class="p">()</span>
<span class="n">gl</span><span class="o">.</span><span class="n">v2f</span><span class="p">(</span><span class="mf">0.0</span><span class="p">,</span> <span class="mf">0.0</span><span class="p">)</span>
<span class="n">gl</span><span class="o">.</span><span class="n">v2f</span><span class="p">(</span><span class="mf">400.0</span><span class="p">,</span> <span class="mf">400.0</span><span class="p">)</span>
<span class="n">gl</span><span class="o">.</span><span class="n">endline</span><span class="p">()</span>
<span class="n">gl</span><span class="o">.</span><span class="n">bgnline</span><span class="p">()</span>
<span class="n">gl</span><span class="o">.</span><span class="n">v2f</span><span class="p">(</span><span class="mf">400.0</span><span class="p">,</span> <span class="mf">0.0</span><span class="p">)</span>
<span class="n">gl</span><span class="o">.</span><span class="n">v2f</span><span class="p">(</span><span class="mf">0.0</span><span class="p">,</span> <span class="mf">400.0</span><span class="p">)</span>
<span class="n">gl</span><span class="o">.</span><span class="n">endline</span><span class="p">()</span>
<span class="n">time</span><span class="o">.</span><span class="n">sleep</span><span class="p">(</span><span class="mi">5</span><span class="p">)</span>
<span class="n">main</span><span class="p">()</span>
</pre></div>
</div>
<div class="admonition-see-also admonition seealso">
<p class="first admonition-title">See also</p>
<dl class="last docutils">
<dt><a class="reference external" href="http://pyopengl.sourceforge.net/">PyOpenGL: The Python OpenGL Binding</a></dt>
<dd><p class="first last" id="index-379">An interface to OpenGL is also available; see information about the <strong>PyOpenGL</strong>
project online at <a class="reference external" href="http://pyopengl.sourceforge.net/">http://pyopengl.sourceforge.net/</a>. This may be a better option
if support for SGI hardware from before about 1996 is not required.</p>
</dd>
</dl>
</div>
</div>
<div class="section" id="module-DEVICE">
<h1>38.9. <tt class="xref docutils literal"><span class="pre">DEVICE</span></tt> — Constants used with the <tt class="xref docutils literal"><span class="pre">gl</span></tt> module<a class="headerlink" href="#module-DEVICE" title="Permalink to this headline">¶</a></h1>
<p><em>Platforms: </em>IRIX</p>
<p class="deprecated">
<span class="versionmodified">Deprecated since version 2.6: </span>The <tt class="xref docutils literal"><span class="pre">DEVICE</span></tt> module has been deprecated for removal in Python 3.0.</p>
<p>This modules defines the constants used by the Silicon Graphics <em>Graphics
Library</em> that C programmers find in the header file <tt class="docutils literal"><span class="pre"><gl/device.h></span></tt>. Read the
module source file for details.</p>
</div>
<div class="section" id="module-GL">
<h1>38.10. <tt class="xref docutils literal"><span class="pre">GL</span></tt> — Constants used with the <tt class="xref docutils literal"><span class="pre">gl</span></tt> module<a class="headerlink" href="#module-GL" title="Permalink to this headline">¶</a></h1>
<p><em>Platforms: </em>IRIX</p>
<p class="deprecated">
<span class="versionmodified">Deprecated since version 2.6: </span>The <tt class="xref docutils literal"><span class="pre">GL</span></tt> module has been deprecated for removal in Python 3.0.</p>
<p>This module contains constants used by the Silicon Graphics <em>Graphics Library</em>
from the C header file <tt class="docutils literal"><span class="pre"><gl/gl.h></span></tt>. Read the module source file for details.</p>
</div>
</div>
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<h3><a href="../contents.html">Table Of Contents</a></h3>
<ul>
<li><a class="reference external" href="#">38.8. <tt class="docutils literal"><span class="pre">gl</span></tt> — <em>Graphics Library</em> interface</a></li>
<li><a class="reference external" href="#module-DEVICE">38.9. <tt class="docutils literal"><span class="pre">DEVICE</span></tt> — Constants used with the <tt class="docutils literal"><span class="pre">gl</span></tt> module</a></li>
<li><a class="reference external" href="#module-GL">38.10. <tt class="docutils literal"><span class="pre">GL</span></tt> — Constants used with the <tt class="docutils literal"><span class="pre">gl</span></tt> module</a></li>
</ul>
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