1<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> 2<html> 3 4<head> 5<META http-equiv="Content-Type" content="text/html; charset=windows-1252"> 6<META name="GENERATOR" content="Microsoft FrontPage 5.0"> 7<META http-equiv="Content-Style-Type" content="text/css"> 8<LINK rel="stylesheet" type="text/css" href="../../CSS/revolution.css"> 9<title>GXPokeAlphaMode</title> 10</head> 11 12<body> 13 14<h1 align="left">GXPokeAlphaMode</h1> 15 16<h2>Syntax</h2> 17<dl><dd><pre class="construction"> 18#include <revolution/gx.h> 19 20void GXPokeAlphaMode( 21 <a href="../Enumerated_Types/GXCompare.html">GXCompare</a> func, 22 u8 threshold ); 23</pre></dd></dl> 24 25<h2>Arguments</h2> 26<TABLE class="arguments" border="1" > 27 <tr> 28<TH>func</TH> 29<TD>Compare function. Accepted values are:<BR> 30 <TABLE class="arguments" border="1" > 31 <tr> 32<TD bgcolor="#C0C0C0">Name</TD> 33<TD bgcolor="#C0C0C0">Compare equation</TD> 34 </tr> 35 <tr> 36<TH>GX_NEVER</TH> 37<TD>Always <CODE>FALSE</CODE>.</TD> 38 </tr> 39 <tr> 40<TH>GX_LESS</TH> 41<TD>( ( <code><em>alpha_src</code></em> < <SPAN class="argument">threshold</SPAN> )</TD> 42 </tr> 43 <tr> 44<TH>GX_LEQUAL</TH> 45<TD>( ( <em><code>alpha_src</code></em> <= <SPAN class="argument">threshold</SPAN> )</TD> 46 </tr> 47 <tr> 48<TH>GX_EQUAL</TH> 49<TD>( ( <em><code>alpha_src</code></em> == <SPAN class="argument">threshold</SPAN> )</TD> 50 </tr> 51 <tr> 52<TH>GX_NEQUAL</TH> 53<TD>( ( <em><code>alpha_src</code></em> != <SPAN class="argument">threshold</SPAN> )</TD> 54 </tr> 55 <tr> 56<TH>GX_GEQUAL</TH> 57<TD>( ( <em><code>alpha_src</code></em> >= <SPAN class="argument">threshold</SPAN> )</TD> 58 </tr> 59 <tr> 60<TH>GX_GREATER</TH> 61<TD>( ( <em><code>alpha_src</code></em> > <SPAN class="argument">threshold</SPAN> )</TD> 62 </tr> 63 <tr> 64<TH>GX_ALWAYS</TH> 65<TD>Always <CODE>TRUE</CODE>.</TD> 66 </tr> 67 </TABLE> 68 </TD> 69 </tr> 70 <tr> 71<TH>threshold</TH> 72<TD>Threshold to which source alpha is compared.</TD> 73 </tr> 74</TABLE> 75 76<h2>Return Values</h2> 77<p>None.</p> 78 79<H2>Description</H2> 80<P>This function sets alpha and threshold value for pixels written to the embedded frame buffer (EFB) using the <CODE>GXPoke*</CODE> functions. The <CODE>GXPoke*</CODE> functions are for writing directly to the EFB from the CPU. Comparative functions are specified as follows.</P> 81<DL><DD><CODE>src_alpha</CODE> <SPAN class="argument">func</SPAN> <SPAN class="argument">threshold</SPAN><BR> <BR> for example:<BR><CODE>src_alpha > 0x80</CODE></DD></DL> 82<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> 83<P>Alpha comparison tests are processed before Z comparisons and blend processing.( See the <A href="GXPokeBlendMode.html"><CODE>GXPokeBlendMode</CODE></A> function.)</P> 84 85<h2>See Also</h2> 86<P class="reference"> 87<A href="GXPokeARGB.html">GXPokeARGB</A>, 88<A href="GXPokeBlendMode.html">GXPokeBlendMode</A> 89</p> 90 91<h2>Revision History</h2> 92<p> 932006/03/01 Initial version.<br> 94</p> 95 96<hr><p>CONFIDENTIAL</p></body> 97</html>