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><head><title>glScissor</title><link rel="stylesheet" href="style.css" type="text/css"/><meta name="generator" content="DocBook XSL Stylesheets V1.59.1"/><link rel="home" href="index.xml" title="PyOpenGL 2.0.1.07 Man Pages"/><link rel="up" href="reference-GL.xml" title="GL"/><link rel="previous" href="glScale.3G.xml" title="glScale"/><link rel="next" href="glSelectBuffer.3G.xml" title="glSelectBuffer"/></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">glScissor</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="glScale.3G.xml">Prev</a></td><th width="60%" align="center">GL</th><td width="20%" align="right"><a accesskey="n" href="glSelectBuffer.3G.xml">Next</a></td></tr></table><hr/></div><div class="refentry" lang="en"><a name="glScissor.3G"/><div class="titlepage"/><div class="refnamediv"><a name="glScissor.3G-name"/><h2>Name</h2><p>glScissor — define the scissor box</p></div><div class="refsynopsisdiv"><a name="glScissor.3G-c_spec"/><h2>C Specification</h2><table class="funcprototype" border="0" cellpadding="0" cellspacing="0"><tr><td valign="top"><code>void<tt>glScissor</tt></code></td><td valign="top"><code>(</code></td><td valign="top"><code>GLint<i><tt>x</tt></i>, GLint<i><tt>y</tt></i>, GLsizei<i><tt>width</tt></i>, GLsizei<i><tt>height</tt></i>);</code></td></tr></table></div><div class="refsynopsisdiv"><a name="glScissor.3G-python_spec"/><h2>Python Specification</h2><table class="funcprototype" border="0" cellpadding="0" cellspacing="0"><tr><td valign="top"><code><tt>glScissor</tt></code></td><td valign="top"><code>(</code></td><td valign="top"><code><i><tt>x</tt></i>, <i><tt>y</tt></i>, <i><tt>width</tt></i>, <i><tt>height</tt></i>) →<tt>None</tt></code></td></tr></table></div><div class="refsect1" lang="en"><a name="glScissor.3G-parameters"/><h2>Parameters</h2><div class="variablelist"><dl><dt><span class="term"><i><tt>x</tt></i>, <i><tt>y</tt></i></span></dt><dd>
Specify the lower left corner of the scissor box. Initially (0, 0).
</dd><dt><span class="term"><i><tt>width</tt></i>, <i><tt>height</tt></i></span></dt><dd>
Specify the width and height of the scissor box. When a GL context is first attached to a window,
<i><tt>width</tt></i> and <i><tt>height</tt></i> are set to the dimensions of that window.
</dd></dl></div></div><div class="refsect1" lang="en"><a name="glScissor.3G-description"/><h2>Description</h2><p>
<tt>glScissor</tt> defines a rectangle, called the scissor box, in window coordinates. The first two
arguments, <i><tt>x</tt></i> and <i><tt>y</tt></i>, specify the lower left corner of the box.
<i><tt>width</tt></i> and <i><tt>height</tt></i> specify the width and height of the box.
</p><p>
To enable and disable the scissor test, call <a href="glEnable.3G.xml"><tt>glEnable</tt></a> and <a href="glEnable.3G.xml"><tt>glDisable</tt></a> with argument <tt>GL_SCISSOR_TEST</tt>. 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. glScissor(0,0,1,1) allows
modification of only the lower left pixel in the window, and glScissor(0,0,0,0) 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" lang="en"><a name="glScissor.3G-errors"/><h2>Errors</h2><p>
<tt>GL_INVALID_VALUE</tt> is generated if either <i><tt>width</tt></i> or
<i><tt>height</tt></i> is negative.
</p><p>
<tt>GL_INVALID_OPERATION</tt> is generated if <tt>glScissor</tt> is executed between the
execution of <a href="glBegin.3G.xml"><tt>glBegin</tt></a> and the corresponding execution of <a href="glBegin.3G.xml"><tt>glEnd</tt></a>.
</p></div><div class="refsect1" lang="en"><a name="glScissor.3G-associated_gets"/><h2>Associated Gets</h2><p>
<tt>glGet</tt> with argument <tt>GL_SCISSOR_BOX</tt>
</p><p>
<a href="glIsEnabled.3G.xml"><tt>glIsEnabled</tt></a> with argument <tt>GL_SCISSOR_TEST</tt>
</p></div><div class="refsect1" lang="en"><a name="glScissor.3G-see_also"/><h2>See Also</h2><p>
<span class="simplelist"><a href="glEnable.3G.xml">glEnable</a>, <a href="glViewport.3G.xml">glViewport</a></span>
</p></div></div><div class="navfooter"><hr/><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="glScale.3G.xml">Prev</a></td><td width="20%" align="center"><a accesskey="u" href="reference-GL.xml">Up</a></td><td width="40%" align="right"><a accesskey="n" href="glSelectBuffer.3G.xml">Next</a></td></tr><tr><td width="40%" align="left" valign="top">glScale</td><td width="20%" align="center"><a accesskey="h" href="index.xml">Home</a></td><td width="40%" align="right" valign="top">glSelectBuffer</td></tr></table></div></body></html>
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