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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"><html><head><!-- 这篇文章由Dancingwind翻译，作者的联系方式zhouwei02@mails.tsinghua.edu.cn --><title>NeHe OpenGL教程第二十九课，DancingWind翻译</title>
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<td align="center" valign="middle" width="75%"><font color="#ffccaa" size="+3"><b><i>第29课</i></b></font></td>
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<td width="74%"><p><font class="head">Blitter 函数:</font></p>
<p><font size="3">类似于DirectDraw的blit函数，过时的技术，我们有实现了它。它非常的简单，就是把一块纹理贴到另一块纹理上。</font></p></td>
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<table border="0" cellpadding="0" cellspacing="0" width="100%"><tbody><tr><td><img src="Tutorial_29_files/tl.png" height="28" width="28"></td><td width="100%"><img src="Tutorial_29_files/tc.png" height="28" width="100%"></td><td><img src="Tutorial_29_files/tr.png" height="28" width="28"></td></tr></tbody></table><table border="0" cellpadding="0" cellspacing="0" width="100%"><tbody><tr><td background="Tutorial_29_files/l.png"><img src="Tutorial_29_files/l.png"></td>
<td valign="top" width="100%">这篇文章是有Andreas Lffler所写的，它写了一份原始的教程。过了几天，Rob Fletcher发了封邮件给我，他重新改写了所有的代码，我在它的基础上把glut的框架变换为Win32的框架。
<p>现在让我们开始吧！</p></td><td background="Tutorial_29_files/r.png"><img src="Tutorial_29_files/r.png"></td></tr></tbody></table><table border="0" cellpadding="0" cellspacing="0" width="100%"><tbody><tr><td><img src="Tutorial_29_files/bl.png" height="28" width="28"></td><td width="100%"><img src="Tutorial_29_files/bc.png" height="28" width="100%"></td><td><img src="Tutorial_29_files/br.png" height="28" width="28"></td></tr></tbody></table>
<font color="#aaffaa" size="3"> </font>
<table border="0" cellpadding="0" cellspacing="0" width="100%"><tbody><tr><td><img src="Tutorial_29_files/tl.png" height="28" width="28"></td><td width="100%"><img src="Tutorial_29_files/tc.png" height="28" width="100%"></td><td><img src="Tutorial_29_files/tr.png" height="28" width="28"></td></tr></tbody></table><table border="0" cellpadding="0" cellspacing="0" width="100%"><tbody><tr><td background="Tutorial_29_files/l.png"><img src="Tutorial_29_files/l.png"></td>
<td valign="top" width="100%">下面是一个保存图像数据的结构</td>
<td background="Tutorial_29_files/r.png"><img src="Tutorial_29_files/r.png"></td></tr></tbody></table><table border="0" cellpadding="0" cellspacing="0" width="100%"><tbody><tr><td><img src="Tutorial_29_files/bl.png" height="28" width="28"></td><td width="100%"><img src="Tutorial_29_files/bc.png" height="28" width="100%"></td><td><img src="Tutorial_29_files/br.png" height="28" width="28"></td></tr></tbody></table><font color="#aaffaa" size="3">
</font><pre><font color="#aaffaa" size="3">typedef struct Texture_Image
{
int width; <font color="#ffffaa">// 宽</font>
int height; <font color="#ffffaa">// 高</font>
int format; <font color="#ffffaa">// 像素格式</font>
unsigned char *data; <font color="#ffffaa">// 纹理数据</font>
} TEXTURE_IMAGE;
</font></pre>
<table border="0" cellpadding="0" cellspacing="0" width="100%"><tbody><tr><td><img src="Tutorial_29_files/tl.png" height="28" width="28"></td><td width="100%"><img src="Tutorial_29_files/tc.png" height="28" width="100%"></td><td><img src="Tutorial_29_files/tr.png" height="28" width="28"></td></tr></tbody></table><table border="0" cellpadding="0" cellspacing="0" width="100%"><tbody><tr><td background="Tutorial_29_files/l.png"><img src="Tutorial_29_files/l.png"></td>
<td valign="top" width="100%">接下来定义了两个指向这个结构的指针</td>
<td background="Tutorial_29_files/r.png"><img src="Tutorial_29_files/r.png"></td></tr></tbody></table><table border="0" cellpadding="0" cellspacing="0" width="100%"><tbody><tr><td><img src="Tutorial_29_files/bl.png" height="28" width="28"></td><td width="100%"><img src="Tutorial_29_files/bc.png" height="28" width="100%"></td><td><img src="Tutorial_29_files/br.png" height="28" width="28"></td></tr></tbody></table><font color="#aaffaa" size="3">
<pre>typedef TEXTURE_IMAGE *P_TEXTURE_IMAGE;
P_TEXTURE_IMAGE t1; <font color="#ffffaa">// 指向保存图像结构的指针</font>
P_TEXTURE_IMAGE t2; <font color="#ffffaa">// 指向保存图像结构的指针</font>
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</font><table border="0" cellpadding="0" cellspacing="0" width="100%"><tbody><tr><td><img src="Tutorial_29_files/tl.png" height="28" width="28"></td><td width="100%"><img src="Tutorial_29_files/tc.png" height="28" width="100%"></td><td><img src="Tutorial_29_files/tr.png" height="28" width="28"></td></tr></tbody></table><table border="0" cellpadding="0" cellspacing="0" width="100%"><tbody><tr><td background="Tutorial_29_files/l.png"><img src="Tutorial_29_files/l.png"></td>
<td valign="top" width="100%">下面的函数为w*h的图像分配内存</td>
<td background="Tutorial_29_files/r.png"><img src="Tutorial_29_files/r.png"></td></tr></tbody></table><table border="0" cellpadding="0" cellspacing="0" width="100%"><tbody><tr><td><img src="Tutorial_29_files/bl.png" height="28" width="28"></td><td width="100%"><img src="Tutorial_29_files/bc.png" height="28" width="100%"></td><td><img src="Tutorial_29_files/br.png" height="28" width="28"></td></tr></tbody></table><font color="#aaffaa" size="3">
<pre>P_TEXTURE_IMAGE AllocateTextureBuffer( GLint w, GLint h, GLint f)
{
P_TEXTURE_IMAGE ti=NULL;
unsigned char *c=NULL; </pre>
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<pre> ti = (P_TEXTURE_IMAGE)malloc(sizeof(TEXTURE_IMAGE)); <font color="#ffffaa">// 分配图像结构内存</font>
if( ti != NULL ) {
ti->width = w; <font color="#ffffaa">// 设置宽度</font>
ti->height = h; <font color="#ffffaa">// 设置高度</font>
ti->format = f; <font color="#ffffaa">// 设置格式</font>
<font color="#ffffaa">// 分配w*h*f个字节</font>
c = (unsigned char *)malloc( w * h * f);
if ( c != NULL ) {
ti->data = c;
}
else {
MessageBox(NULL,"内存不足","分配图像内存错误",MB_OK | MB_ICONINFORMATION);
return NULL;
}
}
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</font><pre><font color="#aaffaa" size="3"> else
{
MessageBox(NULL,"内存不足","分配图像结构内存错误",MB_OK | MB_ICONINFORMATION);
return NULL;
}
return ti; <font color="#ffffaa">// 返回指向图像数据的指针</font>
}
</font></pre>
<table border="0" cellpadding="0" cellspacing="0" width="100%"><tbody><tr><td><img src="Tutorial_29_files/tl.png" height="28" width="28"></td><td width="100%"><img src="Tutorial_29_files/tc.png" height="28" width="100%"></td><td><img src="Tutorial_29_files/tr.png" height="28" width="28"></td></tr></tbody></table><table border="0" cellpadding="0" cellspacing="0" width="100%"><tbody><tr><td background="Tutorial_29_files/l.png"><img src="Tutorial_29_files/l.png"></td>
<td valign="top" width="100%">下面的函数释放分配的内存</td>
<td background="Tutorial_29_files/r.png"><img src="Tutorial_29_files/r.png"></td></tr></tbody></table><table border="0" cellpadding="0" cellspacing="0" width="100%"><tbody><tr><td><img src="Tutorial_29_files/bl.png" height="28" width="28"></td><td width="100%"><img src="Tutorial_29_files/bc.png" height="28" width="100%"></td><td><img src="Tutorial_29_files/br.png" height="28" width="28"></td></tr></tbody></table><font color="#aaffaa" size="3">
<pre><font color="#ffffaa">// 释放图像内存</font>
void DeallocateTexture( P_TEXTURE_IMAGE t )
{
if(t)
{
if(t->data)
{
free(t->data); <font color="#ffffaa">// 释放图像内存</font>
}
free(t); <font color="#ffffaa"> // 释放图像结构内存</font>
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