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13
14<h1 align="left">GXReadBoundingBox</h1>
15
16<h2>Syntax</h2>
17<dl><dd><pre class="construction">
18#include &lt;revolution/gx.h&gt;
19
20void GXReadBoundingBox(
21    u16*       left,
22    u16*       top,
23    u16*       right,
24    u16*       bottom );
25</pre></dd></dl>
26
27<h2>Arguments</h2>
28<TABLE class="arguments" border="1" >
29  <tr>
30    <TH>left</TH>
31    <TD>The leftmost pixel in the bounding box.</TD>
32  </tr>
33  <tr>
34    <TH>top</TH>
35    <TD>The uppermost line in the bounding box.</TD>
36  </tr>
37  <tr>
38    <TH>right</TH>
39    <TD>The rightmost pixel in the bounding box.</TD>
40  </tr>
41  <tr>
42    <TH>bottom</TH>
43    <TD>The lowest line in the bounding box.</TD>
44  </tr>
45</TABLE>
46
47<h2>Return Values</h2>
48<p>None.</p>
49
50<H2>Description</H2>
51<P>The graphics hardware keeps track of a bounding box of pixel coordinates that is rendered in the embedded frame buffer (EFB).&nbsp;These bounding box values can be used to determine the area of the EFB to copy using the <A href="GXSetTexCopySrc.html"><CODE>GXSetTexCopySrc</CODE></A> function.</P>
52<P>This function reads the bounding box values.&nbsp;The <A href="GXClearBoundingBox.html"><CODE>GXClearBoundingBox</CODE></A> function can be used to reset the values of the bounding box.</P>
53<P>Since hardware can only test the bounding box in quads (2x2 pixel blocks), the result of this function may contain an error of plus or minus 1 pixel. Also because of this, <SPAN class="argument">left</SPAN> and <SPAN class="argument">top</SPAN> are always even-numbered and <SPAN class="argument">right</SPAN> and <SPAN class="argument">bottom</SPAN> are always odd-numbered.</P>
54
55<h2>See Also</h2>
56<P class="reference">
57<A href="GXClearBoundingBox.html">GXClearBoundingBox</A>
58</p>
59
60<H2>Revision History</H2>
61<P>
622006/03/01 Initial version.<br>
63</P>
64
65<hr><p>CONFIDENTIAL</p></body>
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