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8<TITLE>GXInitLightDir</TITLE>
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11<H1 align="left">GXInitLightDir</H1>
12
13<H2>Syntax</H2>
14<dl><dd><pre class="construction">
15#include &lt;revolution/gx.h&gt;
16
17void GXInitLightDir(
18    <A href="../Structures/GXLightObj.html">GXLightObj</A>* lt_obj,
19    f32         nx,
20    f32         ny,
21    f32         nz );
22</pre></dd></dl>
23
24<H2>Arguments</H2>
25<TABLE class="arguments" border="1" >
26  <TBODY>
27    <TR>
28<TH>lt_obj</TH>
29<TD>Pointer to a light object.</TD>
30    </TR>
31    <TR>
32<TH>nx</TH>
33<TD>X coordinate for the light direction.</TD>
34    </TR>
35    <TR>
36<TH>ny</TH>
37<TD>Y coordinate for the light direction.</TD>
38    </TR>
39    <TR>
40<TH>nz</TH>
41<TD>Z coordinate for the light direction</TD>
42    </TR>
43  </TBODY>
44</TABLE>
45
46<H2>Return Values</H2>
47<P>None.</P>
48
49<H2>Description</H2>
50<P>This function sets the direction of light in the light object.&nbsp;This direction is used when the light object is used as spotlight (see the <SPAN class="argument">attn_fn</SPAN> argument of the <A href="GXSetChanCtrl.html"><CODE>GXSetChanCtrl</CODE></A> function). The memory for the light object must be allocated by the application; this function does not load any hardware registers.&nbsp;To load a light object into a hardware light, use the <A href="GXLoadLightObjImm.html"><CODE>GXLoadLightObjImm</CODE></A> or <A href="GXLoadLightObjIndx.html"><CODE>GXLoadLightObjIndx</CODE></A> function.</P>
51<P>The coordinate space of the light direction should be consistent with a vertex normal transformed by a normal matrix; i.e., it should be transformed to view space. The direction vector is required to be normalized.</P>
52<P><B>Note:</B> This function can't specify the direction of parallel directional diffuse lights. To use parallel diffuse lights, place the light position very far from all objects to be lit. (See the <A href="GXGetLightPos.html"><CODE>GXInitLightPos</CODE></A> and  <A href="GXSetChanCtrl.html"><CODE>GXSetChanCtrl</CODE></A> functions.)</P>
53
54<H2>See Also</H2>
55<P class="reference">
56<A href="GXInitLightPos.html">GXInitLightPos</A>,
57<A href="GXLoadLightObjImm.html">GXLoadLightObjImm</A>,
58<A href="GXLoadLightObjIndx.html">GXLoadLightObjIndx</A>,
59<A href="GXSetChanCtrl.html">GXSetChanCtrl</A>,
60<A href="GXGetLightDir.html">GXGetLightDir</A>,
61<A href="GXLightObjInitFlow.html">GXLightObj Initialization Flow</A>
62</P>
63
64<H2>Revision History</H2>
65<P>
662006/03/01 Initial version.<br>
67</P>
68
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