<function>glScissorIndexed</function> defines the scissor box for a specified viewport.
<parameter>index</parameter> specifies the index of scissor box to modify.
<parameter>index</parameter> must be less than the value of <constant>GL_MAX_VIEWPORTS</constant>.
For <function>glScissorIndexed</function>, <parameter>left</parameter>, <parameter>bottom</parameter>,
<parameter>width</parameter> and <parameter>height</parameter> specify the left, bottom, width
and height of the scissor box, in pixels, respectively.
For <function>glScissorIndexedv</function>, <parameter>v</parameter> specifies the address of an
array containing integers specifying the lower left corner of the scissor box, and the width and
height of the scissor box, in that order.
</para>
<para>
To enable and disable the scissor test, call
<citerefentry><refentrytitle>glEnable</refentrytitle></citerefentry> and <citerefentry><refentrytitle>glDisable</refentrytitle></citerefentry> with argument
<constant>GL_SCISSOR_TEST</constant>. The test is initially disabled for all viewports.
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>glScissor(0,0,1,1)</code> allows modification of only the lower left
pixel in the window, and <code>glScissor(0,0,0,0)</code> doesn't allow
modification of any pixels in the window.
</para>
<para>
When the scissor test is disabled,
it is as though the scissor box includes the entire window.
</para>
</refsect1>
<refsect1id="errors"><title>Errors</title>
<para>
<constant>GL_INVALID_VALUE</constant> is generated if <parameter>index</parameter> is greater than or equal to
the value of <constant>GL_MAX_VIEWPORTS</constant>.
</para>
<para>
<constant>GL_INVALID_VALUE</constant> is generated if any width or height specified in the array <parameter>v</parameter> is negative.