tutorial_17.htm

如果你相信它就好好学学吧,同样这里也只是个入门

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    <td background="Tutorial_17_files/l.gif"><img src="Tutorial_17_files/l.gif" height="28" width="28"></td>
    <td valign="top" width="100%">现在我们所要做的是恢复透视视图。我们选择投影矩阵并用glPopMatrix()恢复我们先前用glPushMatrix()保存的设置。用相反的顺序恢复设置很重要。 
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<pre>	glMatrixMode(GL_PROJECTION);						<font color="#ffffaa">// 选择投影矩阵</font>
	glPopMatrix();								<font color="#ffffaa">// 设置为保存的矩阵</font>
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    <td background="Tutorial_17_files/l.gif"><img src="Tutorial_17_files/l.gif" height="28" width="28"></td>
    <td valign="top" width="100%">现在我们选择模型视点矩阵，做相同的工作。我们使用glPopMatrix()恢复模型视点矩阵到我们设置正交投影显示之前。 
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<pre>	glMatrixMode(GL_MODELVIEW);							<font color="#ffffaa">// 选择模型矩阵</font>
	glPopMatrix();								<font color="#ffffaa">// 设置为保存的矩阵</font>
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    <td valign="top" width="100%">最后，我们启用深度测试。如果你没有在上面的代码中关闭深度测试，你不需要这行。 </td>
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<pre>	glEnable(GL_DEPTH_TEST);						<font color="#ffffaa">// 启用深度测试</font>
}
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    <td valign="top" width="100%">我们没有修改ReSizeGLScene()，所以我们直接跳到InitGL()。<br></td>
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<pre>int InitGL(GLvoid)								<font color="#ffffaa">// 此处开始对OpenGL进行所有设置</font>
{
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    <td valign="top" width="100%">我们跳到创建纹理的代码。如果由于某种原因创建纹理失败了，我们返回FALSE。这将让我们的程序知道发生了一个错误从而关闭程序。</td>
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<pre>	if (!LoadGLTextures())							<font color="#ffffaa">// 调用纹理载入子例程</font>
	{
		return FALSE;							<font color="#ffffaa">// 如果未能载入，返回FALSE</font>
	}
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    <td background="Tutorial_17_files/l.gif"><img src="Tutorial_17_files/l.gif" height="28" width="28"></td>
    <td valign="top" width="100%">如果没有错，我们跳到创建字体的代码。在创建字体时不会出什么错所以我们省略了错误检查。 <br></td>
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<pre>	BuildFont();								<font color="#ffffaa">// 创建字符显示列表</font>
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    <td valign="top" width="100%">现在我们做通常的GL设置。我们将背景色设为黑色，将深度清为1.0。我们选择一个深度测试模式和一个混合模式。我们启用平滑着色，最后启用2维纹理映射。</td>
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<pre>	glClearColor(0.0f, 0.0f, 0.0f, 0.0f);					<font color="#ffffaa">// 黑色背景 </font>
	glClearDepth(1.0);							<font color="#ffffaa">	// 设置深度缓存</font>
	glDepthFunc(GL_LEQUAL);							<font color="#ffffaa">// 所作深度测试的类型</font>
	glBlendFunc(GL_SRC_ALPHA,GL_ONE);						<font color="#ffffaa">// 设置混合因子</font>
	glShadeModel(GL_SMOOTH);							<font color="#ffffaa">// 启用阴影平滑</font>
	glEnable(GL_TEXTURE_2D);							<font color="#ffffaa">// </font><font color="#aaffaa" size="3"><font color="#ffffaa">启用纹理映射</font></font>
	return TRUE;								<font color="#ffffaa">// 初始化成功</font>
}
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    <td valign="top" width="100%">下面这段代码将完成绘图。我们先绘制3D物体最后绘制文字，这样文字将显示在3D物体上面，而不会被3D物体遮住。我之所以加入一个3D物体是为了演示透视投影和正交投影可同时使用。</td>
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<pre>int DrawGLScene(GLvoid)								<font color="#ffffaa">// 从这里开始进行所有的绘制</font>
{
	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);			<font color="#ffffaa">	// 清除屏幕和深度缓存</font>
	glLoadIdentity();							<font color="#ffffaa">	// 重置当前的模型观察矩阵</font>
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