<div class="refentry"><a id="glScissor"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>glScissor — define the scissor box</p></div><div class="refsynopsisdiv"><h2>C Specification</h2><div class="funcsynopsis"><table class="funcprototype-table" style="cellspacing: 0; cellpadding: 0;"><tr><td><code class="funcdef">void <strong class="fsfunc">glScissor</strong>(</code></td><td>GLint <var class="pdparam">x</var>, </td></tr><tr><td> </td><td>GLint <var class="pdparam">y</var>, </td></tr><tr><td> </td><td>GLsizei <var class="pdparam">width</var>, </td></tr><tr><td> </td><td>GLsizei <var class="pdparam">height</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div></div></div><div class="refsect1"><a id="parameters"></a><h2>Parameters</h2><div class="variablelist"><dl class="variablelist"><dt><span class="term"><em class="parameter"><code>x</code></em>, </span><span class="term"><em class="parameter"><code>y</code></em></span></dt><dd><p>

Specify the lower left corner of the scissor box.

Initially (0, 0).

</p></dd><dt><span class="term"><em class="parameter"><code>width</code></em>, </span><span class="term"><em class="parameter"><code>height</code></em></span></dt><dd><p>

Specify the width and height of the scissor box.

When a GL context is first attached to a window,

<em class="parameter"><code>width</code></em> and <em class="parameter"><code>height</code></em> are set to the dimensions of that

window.

</p></dd></dl></div></div><div class="refsect1"><a id="description"></a><h2>Description</h2><p>

<code class="function">glScissor</code> defines a rectangle, called the scissor box,

in window coordinates.

The first two arguments,

<em class="parameter"><code>x</code></em> and <em class="parameter"><code>y</code></em>,

specify the lower left corner of the box.

<em class="parameter"><code>width</code></em> and <em class="parameter"><code>height</code></em> specify the width and height of the box.

</p><p>

To enable and disable the scissor test, call

<a class="citerefentry" href="glEnable"><span class="citerefentry"><span class="refentrytitle">glEnable</span></span></a> and <a class="citerefentry" href="glDisable"><span class="citerefentry"><span class="refentrytitle">glDisable</span></span></a> with argument

<code class="constant">GL_SCISSOR_TEST</code>. The test is initially disabled.

While the test is enabled, only pixels that lie within the scissor box

can be modified by drawing commands.

Window coordinates have integer values at the shared corners of

frame buffer pixels.

<code class="code">glScissor(0,0,1,1)</code> allows modification of only the lower left

pixel in the window, and <code class="code">glScissor(0,0,0,0)</code> doesn't allow

modification of any pixels in the window.

</p><p>

When the scissor test is disabled,

it is as though the scissor box includes the entire window.

</p></div><div class="refsect1"><a id="errors"></a><h2>Errors</h2><p>

<code class="constant">GL_INVALID_VALUE</code> is generated if either <em class="parameter"><code>width</code></em> or <em class="parameter"><code>height</code></em> is negative.

</p></div><div class="refsect1"><a id="associatedgets"></a><h2>Associated Gets</h2><p>

<a class="citerefentry" href="glGet"><span class="citerefentry"><span class="refentrytitle">glGet</span></span></a> with argument <code class="constant">GL_SCISSOR_BOX</code>

</p><p>

<a class="citerefentry" href="glIsEnabled"><span class="citerefentry"><span class="refentrytitle">glIsEnabled</span></span></a> with argument <code class="constant">GL_SCISSOR_TEST</code>

</p></div>

{$pipelinestall}{$examples}

<div class="refsect1"><a id="seealso"></a><h2>See Also</h2><p>

<a class="citerefentry" href="glEnable"><span class="citerefentry"><span class="refentrytitle">glEnable</span></span></a>,

<a class="citerefentry" href="glViewport"><span class="citerefentry"><span class="refentrytitle">glViewport</span></span></a>

</p></div><div class="refsect1"><div id="Copyright"><h2>Copyright</h2><p>

Copyright © 1991-2006

Silicon Graphics, Inc. This document is licensed under the SGI

Free Software B License. For details, see

<a class="ulink" href="https://web.archive.org/web/20171022161616/http://oss.sgi.com/projects/FreeB/" target="_top">https://web.archive.org/web/20171022161616/http://oss.sgi.com/projects/FreeB/</a>.

</p></div></div></div>