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9<title>GXPokeAlphaMode</title>
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13
14<h1 align="left">GXPokeAlphaMode</h1>
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16
17<h2>C Specification</h2>
18
19<dl>
20<dd><PRE><CODE>#include &lt;revolution/gx.h&gt;</CODE></PRE></dd>
21<dd><pre><CODE>void GXPokeAlphaMode(
22<a href="../Enumerated_Types/GXCompare.html">GXCompare</a>    func,
23u8        threshold );</CODE></pre>
24  </dd>
25</dl>
26
27<h2>Arguments</h2>
28<TABLE border="1" cellpadding="3" cellspacing="0.1">
29  <tr>
30<TD width="120" valign="top" bgcolor="#ffffe8"><em><strong><CODE>func</font></strong></em></TD>
31<TD width="520">Compare function. <BR>Accepted values are:<br>
32      <TABLE width="500" border="1" cellspacing="0.1">
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34          <tr>
35<TD bgcolor="#C0C0C0" width="150">Name</TD>
36<TD bgcolor="#C0C0C0" width="350">Compare equation</TD>
37          </tr>
38          <tr>
39<TD width="150"><code>GX_NEVER</code></TD>
40<TD width="350">Never true.</TD>
41          </tr>
42          <tr>
43<TD width="150"><code>GX_LESS</code></TD>
44<TD width="350"><em><code>(alpha_src &lt;<strong><CODE> </font>threshold</strong>)</code></em></TD>
45          </tr>
46          <tr>
47<TD width="150"><code>GX_LEQUAL</code></TD>
48<TD width="350"><em><code>(alpha_src &lt;=<strong><CODE> </font>threshold</strong>)</code></em></TD>
49          </tr>
50          <tr>
51<TD height="25" width="150"><code>GX_EQUAL</code></TD>
52<TD height="25" width="350"><em><code>(alpha_src ==<strong><CODE></font>threshold</strong>)</code></em></TD>
53          </tr>
54          <tr>
55<TD width="150"><code>GX_NEQUAL</code></TD>
56<TD width="350"><em><code>(alpha_src !=<strong><CODE> </font>threshold</strong>)</code></em></TD>
57          </tr>
58          <tr>
59<TD width="150"><code>GX_GEQUAL</code></TD>
60<TD width="350"><em><code>(alpha_src &gt;=<strong><CODE> </font>threshold</strong>)</code></em></TD>
61          </tr>
62          <tr>
63<TD width="150"><code>GX_GREATER</code></TD>
64<TD width="350"><em><code>(alpha_src &gt;<strong><CODE> </font>threshold</strong>)</code></em></TD>
65          </tr>
66          <tr>
67<TD width="150"><code>GX_ALWAYS</code></TD>
68<TD width="350">Always true.</TD>
69          </tr>
70
71      </TABLE>
72      </TD>
73    </tr>
74  <tr>
75<TD width="120" valign="top" bgcolor="#ffffe8"><em><strong><CODE>threshold</font></strong></em></TD>
76<TD width="520">Threshold to which source alpha is compared.</TD>
77    </tr>
78</TABLE>
79<h2>Return Values</h2>
80
81<p>None.</p>
82<H2>Description</H2>
83<P>This function sets alpha  and threshold value for pixels written to the Embedded Frame Buffer (EFB) using the <code>GXPoke*</code> functions.&nbsp;The <CODE>GXPoke*</CODE> functions are for writing directly to the EFB from the CPU. Comparative functions are specified as follows:</P>
84<P><CODE>src_alpha&nbsp; <EM><STRONG>func</STRONG></EM>&nbsp; <STRONG><EM>threshold</EM><BR> <BR></STRONG>for example:<BR>src_alpha &gt; 0x80</CODE></P>
85<P>Alpha comparative functions use the source alpha channel as a template and can be used for conditional writing of pixels to the EFB. When compare functions are true, the source color is written to the EFB based on the Z comparison results.(See the <A href="GXPokeZMode.html"><CODE>GXPokeZMode</CODE></A> function.) No writes are performed when the alpha comparison functions are false.</P>
86<P>Alpha comparison tests are processed before Z comparisons and blend processing.(See the <A href="GXPokeBlendMode.html"><CODE>GXPokeBlendMode</CODE></A> function.)</P>
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90
91<h2>See Also</h2>
92<p><a href="GXPokeARGB.html">GXPokeARGB</a><a href="GXPokeBlendMode.html"><br> GXPokeBlendMode</a><br></p>
93<h2>Revision History</h2><p>03/01/2006 Initial version</p></body>
94</html>