OpenGL ES(1) - 构建OpenGL ES环境

为了使用OpenGL ES绘制图像，你需要创建一个视图容器。最直接的方法就是实现一个GLSurfaceView和一个GLSurfaceView.Renderer。GLSurfaceView是视图容器，而GLSurfaceView.Renderer控制绘制什么到视图中。

GLSurfaceView只是加入OpenGL ES到你的程序的一种方法。对于全屏或者将近全屏的图像视图，它是合适的选择。如果需要嵌入小部分区域到你的布局中，你应该使用TextureView。

在清单文件中声明OpenGL ES

如果要使用OpenGL ES 2.0 API，你必须在清单文件中声明：

<span class="tag" style="color: rgb(0, 0, 136);"><uses-feature</span><span class="pln" style="color: rgb(0, 0, 0);"> </span><span class="atn" style="color: rgb(136, 34, 136);">android:glEsVersion</span><span class="pun" style="color: rgb(102, 102, 0);">=</span><span class="atv" style="color: rgb(0, 136, 0);">"0x00020000"</span><span class="pln" style="color: rgb(0, 0, 0);"> </span><span class="atn" style="color: rgb(136, 34, 136);">android:required</span><span class="pun" style="color: rgb(102, 102, 0);">=</span><span class="atv" style="color: rgb(0, 136, 0);">"true"</span><span class="pln" style="color: rgb(0, 0, 0);"> </span><span class="tag" style="color: rgb(0, 0, 136);">/></span>

如果程序使用纹理压缩，你需要声明支持的压缩格式，如果设备不支持这种格式的话，就不能运行你的程序：

<span class="tag" style="color: rgb(0, 0, 136);"><supports-gl-texture</span><span class="pln" style="color: rgb(0, 0, 0);"> </span><span class="atn" style="color: rgb(136, 34, 136);">android:name</span><span class="pun" style="color: rgb(102, 102, 0);">=</span><span class="atv" style="color: rgb(0, 136, 0);">"GL_OES_compressed_ETC1_RGB8_texture"</span><span class="pln" style="color: rgb(0, 0, 0);"> </span><span class="tag" style="color: rgb(0, 0, 136);">/></span><span class="pln" style="color: rgb(0, 0, 0);">
</span><span class="tag" style="color: rgb(0, 0, 136);"><supports-gl-texture</span><span class="pln" style="color: rgb(0, 0, 0);"> </span><span class="atn" style="color: rgb(136, 34, 136);">android:name</span><span class="pun" style="color: rgb(102, 102, 0);">=</span><span class="atv" style="color: rgb(0, 136, 0);">"GL_OES_compressed_paletted_texture"</span><span class="pln" style="color: rgb(0, 0, 0);"> </span><span class="tag" style="color: rgb(0, 0, 136);">/></span>

给OpenGL ES创建一个Activity

<span class="kwd" style="color: rgb(0, 0, 136);">public</span><span class="pln" style="color: rgb(0, 0, 0);"> </span><span class="kwd" style="color: rgb(0, 0, 136);">class</span><span class="pln" style="color: rgb(0, 0, 0);"> </span><span class="typ" style="color: rgb(102, 0, 102);">OpenGLES20</span><span class="pln" style="color: rgb(0, 0, 0);"> </span><span class="kwd" style="color: rgb(0, 0, 136);">extends</span><span class="pln" style="color: rgb(0, 0, 0);"> </span><span class="typ" style="color: rgb(102, 0, 102);">Activity</span><span class="pln" style="color: rgb(0, 0, 0);"> </span><span class="pun" style="color: rgb(102, 102, 0);">{</span><span class="pln" style="color: rgb(0, 0, 0);">

    </span><span class="kwd" style="color: rgb(0, 0, 136);">private</span><span class="pln" style="color: rgb(0, 0, 0);"> </span><span class="typ" style="color: rgb(102, 0, 102);">GLSurfaceView</span><span class="pln" style="color: rgb(0, 0, 0);"> mGLView</span><span class="pun" style="color: rgb(102, 102, 0);">;</span><span class="pln" style="color: rgb(0, 0, 0);">

    </span><span class="lit" style="color: rgb(0, 102, 102);">@Override</span><span class="pln" style="color: rgb(0, 0, 0);">
    </span><span class="kwd" style="color: rgb(0, 0, 136);">public</span><span class="pln" style="color: rgb(0, 0, 0);"> </span><span class="kwd" style="color: rgb(0, 0, 136);">void</span><span class="pln" style="color: rgb(0, 0, 0);"> onCreate</span><span class="pun" style="color: rgb(102, 102, 0);">(</span><span class="typ" style="color: rgb(102, 0, 102);">Bundle</span><span class="pln" style="color: rgb(0, 0, 0);"> savedInstanceState</span><span class="pun" style="color: rgb(102, 102, 0);">)</span><span class="pln" style="color: rgb(0, 0, 0);"> </span><span class="pun" style="color: rgb(102, 102, 0);">{</span><span class="pln" style="color: rgb(0, 0, 0);">
        </span><span class="kwd" style="color: rgb(0, 0, 136);">super</span><span class="pun" style="color: rgb(102, 102, 0);">.</span><span class="pln" style="color: rgb(0, 0, 0);">onCreate</span><span class="pun" style="color: rgb(102, 102, 0);">(</span><span class="pln" style="color: rgb(0, 0, 0);">savedInstanceState</span><span class="pun" style="color: rgb(102, 102, 0);">);</span><span class="pln" style="color: rgb(0, 0, 0);">

        </span><span class="com" style="color: rgb(136, 0, 0);">// Create a GLSurfaceView instance and set it</span><span class="pln" style="color: rgb(0, 0, 0);">
        </span><span class="com" style="color: rgb(136, 0, 0);">// as the ContentView for this Activity.</span><span class="pln" style="color: rgb(0, 0, 0);">
        mGLView </span><span class="pun" style="color: rgb(102, 102, 0);">=</span><span class="pln" style="color: rgb(0, 0, 0);"> </span><span class="kwd" style="color: rgb(0, 0, 136);">new</span><span class="pln" style="color: rgb(0, 0, 0);"> </span><span class="typ" style="color: rgb(102, 0, 102);">MyGLSurfaceView</span><span class="pun" style="color: rgb(102, 102, 0);">(</span><span class="kwd" style="color: rgb(0, 0, 136);">this</span><span class="pun" style="color: rgb(102, 102, 0);">);</span><span class="pln" style="color: rgb(0, 0, 0);">
        setContentView</span><span class="pun" style="color: rgb(102, 102, 0);">(</span><span class="pln" style="color: rgb(0, 0, 0);">mGLView</span><span class="pun" style="color: rgb(102, 102, 0);">);</span><span class="pln" style="color: rgb(0, 0, 0);">
    </span><span class="pun" style="color: rgb(102, 102, 0);">}</span><span class="pln" style="color: rgb(0, 0, 0);">
</span><span class="pun" style="color: rgb(102, 102, 0);">}</span>

提示：OpenGL ES 2.0最低需要Android2.2。

创建一个GLSurfaceView对象

GLSurfaceView完成很少的工作，比如捕获触摸事件等，主要的绘制对象控制在GLSurfaceView.Renderer中。

<span class="kwd" style="color: rgb(0, 0, 136);">class</span><span class="pln" style="color: rgb(0, 0, 0);"> </span><span class="typ" style="color: rgb(102, 0, 102);">MyGLSurfaceView</span><span class="pln" style="color: rgb(0, 0, 0);"> </span><span class="kwd" style="color: rgb(0, 0, 136);">extends</span><span class="pln" style="color: rgb(0, 0, 0);"> </span><span class="typ" style="color: rgb(102, 0, 102);">GLSurfaceView</span><span class="pln" style="color: rgb(0, 0, 0);"> </span><span class="pun" style="color: rgb(102, 102, 0);">{</span><span class="pln" style="color: rgb(0, 0, 0);">

    </span><span class="kwd" style="color: rgb(0, 0, 136);">public</span><span class="pln" style="color: rgb(0, 0, 0);"> </span><span class="typ" style="color: rgb(102, 0, 102);">MyGLSurfaceView</span><span class="pun" style="color: rgb(102, 102, 0);">(</span><span class="typ" style="color: rgb(102, 0, 102);">Context</span><span class="pln" style="color: rgb(0, 0, 0);"> context</span><span class="pun" style="color: rgb(102, 102, 0);">){</span><span class="pln" style="color: rgb(0, 0, 0);">
        </span><span class="kwd" style="color: rgb(0, 0, 136);">super</span><span class="pun" style="color: rgb(102, 102, 0);">(</span><span class="pln" style="color: rgb(0, 0, 0);">context</span><span class="pun" style="color: rgb(102, 102, 0);">);</span><span class="pln" style="color: rgb(0, 0, 0);">

        </span><span class="com" style="color: rgb(136, 0, 0);">// Set the Renderer for drawing on the GLSurfaceView</span><span class="pln" style="color: rgb(0, 0, 0);">
        setRenderer</span><span class="pun" style="color: rgb(102, 102, 0);">(</span><span class="kwd" style="color: rgb(0, 0, 136);">new</span><span class="pln" style="color: rgb(0, 0, 0);"> </span><span class="typ" style="color: rgb(102, 0, 102);">MyRenderer</span><span class="pun" style="color: rgb(102, 102, 0);">());</span><span class="pln" style="color: rgb(0, 0, 0);">
    </span><span class="pun" style="color: rgb(102, 102, 0);">}</span><span class="pln" style="color: rgb(0, 0, 0);">
</span><span class="pun" style="color: rgb(102, 102, 0);">}</span>

如果你使用2.0的话，还需要在构造函数中调用：

<span class="com" style="color: rgb(136, 0, 0);">// Create an OpenGL ES 2.0 context</span><span class="pln" style="color: rgb(0, 0, 0);">
setEGLContextClientVersion</span><span class="pun" style="color: rgb(102, 102, 0);">(</span><span class="lit" style="color: rgb(0, 102, 102);">2</span><span class="pun" style="color: rgb(102, 102, 0);">);</span>

另外一个可选的设置是渲染模式，当只有绘图数据变化时才绘制视图，使用GLSurfaceView.RENDERMODE_WHEN_DIRTY：

<span class="com" style="color: rgb(136, 0, 0);">// Render the view only when there is a change in the drawing data</span><span class="pln" style="color: rgb(0, 0, 0);">
setRenderMode</span><span class="pun" style="color: rgb(102, 102, 0);">(</span><span class="typ" style="color: rgb(102, 0, 102);">GLSurfaceView</span><span class="pun" style="color: rgb(102, 102, 0);">.</span><span class="pln" style="color: rgb(0, 0, 0);">RENDERMODE_WHEN_DIRTY</span><span class="pun" style="color: rgb(102, 102, 0);">);</span>

这个设置表示GLSurfaceView帧在调用requestRender()时才被重画。

构建一个Renderer类

renderer有三个方法用来指出画什么和怎么画一个图像到GLSurfaceView中：

onSurfaceCreated() - 调用一次，用来设置视图的OpenGL ES 环境。
onDrawFrame() - 每次重画视图时调用。
onSurfaceChanged() - 视图的几何形状变化时调用，例如设备屏幕转换。

下面的代码绘制一个灰色背景到GLSurfaceView：

<span class="kwd" style="color: rgb(0, 0, 136);">public</span><span class="pln" style="color: rgb(0, 0, 0);"> </span><span class="kwd" style="color: rgb(0, 0, 136);">class</span><span class="pln" style="color: rgb(0, 0, 0);"> </span><span class="typ" style="color: rgb(102, 0, 102);">MyGL20Renderer</span><span class="pln" style="color: rgb(0, 0, 0);"> </span><span class="kwd" style="color: rgb(0, 0, 136);">implements</span><span class="pln" style="color: rgb(0, 0, 0);"> </span><span class="typ" style="color: rgb(102, 0, 102);">GLSurfaceView</span><span class="pun" style="color: rgb(102, 102, 0);">.</span><span class="typ" style="color: rgb(102, 0, 102);">Renderer</span><span class="pln" style="color: rgb(0, 0, 0);"> </span><span class="pun" style="color: rgb(102, 102, 0);">{</span><span class="pln" style="color: rgb(0, 0, 0);">

    </span><span class="kwd" style="color: rgb(0, 0, 136);">public</span><span class="pln" style="color: rgb(0, 0, 0);"> </span><span class="kwd" style="color: rgb(0, 0, 136);">void</span><span class="pln" style="color: rgb(0, 0, 0);"> onSurfaceCreated</span><span class="pun" style="color: rgb(102, 102, 0);">(</span><span class="pln" style="color: rgb(0, 0, 0);">GL10 unused</span><span class="pun" style="color: rgb(102, 102, 0);">,</span><span class="pln" style="color: rgb(0, 0, 0);"> </span><span class="typ" style="color: rgb(102, 0, 102);">EGLConfig</span><span class="pln" style="color: rgb(0, 0, 0);"> config</span><span class="pun" style="color: rgb(102, 102, 0);">)</span><span class="pln" style="color: rgb(0, 0, 0);"> </span><span class="pun" style="color: rgb(102, 102, 0);">{</span><span class="pln" style="color: rgb(0, 0, 0);">
        </span><span class="com" style="color: rgb(136, 0, 0);">// Set the background frame color</span><span class="pln" style="color: rgb(0, 0, 0);">
        GLES20</span><span class="pun" style="color: rgb(102, 102, 0);">.</span><span class="pln" style="color: rgb(0, 0, 0);">glClearColor</span><span class="pun" style="color: rgb(102, 102, 0);">(</span><span class="lit" style="color: rgb(0, 102, 102);">0.5f</span><span class="pun" style="color: rgb(102, 102, 0);">,</span><span class="pln" style="color: rgb(0, 0, 0);"> </span><span class="lit" style="color: rgb(0, 102, 102);">0.5f</span><span class="pun" style="color: rgb(102, 102, 0);">,</span><span class="pln" style="color: rgb(0, 0, 0);"> </span><span class="lit" style="color: rgb(0, 102, 102);">0.5f</span><span class="pun" style="color: rgb(102, 102, 0);">,</span><span class="pln" style="color: rgb(0, 0, 0);"> </span><span class="lit" style="color: rgb(0, 102, 102);">1.0f</span><span class="pun" style="color: rgb(102, 102, 0);">);</span><span class="pln" style="color: rgb(0, 0, 0);">
    </span><span class="pun" style="color: rgb(102, 102, 0);">}</span><span class="pln" style="color: rgb(0, 0, 0);">

    </span><span class="kwd" style="color: rgb(0, 0, 136);">public</span><span class="pln" style="color: rgb(0, 0, 0);"> </span><span class="kwd" style="color: rgb(0, 0, 136);">void</span><span class="pln" style="color: rgb(0, 0, 0);"> onDrawFrame</span><span class="pun" style="color: rgb(102, 102, 0);">(</span><span class="pln" style="color: rgb(0, 0, 0);">GL10 unused</span><span class="pun" style="color: rgb(102, 102, 0);">)</span><span class="pln" style="color: rgb(0, 0, 0);"> </span><span class="pun" style="color: rgb(102, 102, 0);">{</span><span class="pln" style="color: rgb(0, 0, 0);">
        </span><span class="com" style="color: rgb(136, 0, 0);">// Redraw background color</span><span class="pln" style="color: rgb(0, 0, 0);">
        GLES20</span><span class="pun" style="color: rgb(102, 102, 0);">.</span><span class="pln" style="color: rgb(0, 0, 0);">glClear</span><span class="pun" style="color: rgb(102, 102, 0);">(</span><span class="pln" style="color: rgb(0, 0, 0);">GLES20</span><span class="pun" style="color: rgb(102, 102, 0);">.</span><span class="pln" style="color: rgb(0, 0, 0);">GL_COLOR_BUFFER_BIT</span><span class="pun" style="color: rgb(102, 102, 0);">);</span><span class="pln" style="color: rgb(0, 0, 0);">
    </span><span class="pun" style="color: rgb(102, 102, 0);">}</span><span class="pln" style="color: rgb(0, 0, 0);">

    </span><span class="kwd" style="color: rgb(0, 0, 136);">public</span><span class="pln" style="color: rgb(0, 0, 0);"> </span><span class="kwd" style="color: rgb(0, 0, 136);">void</span><span class="pln" style="color: rgb(0, 0, 0);"> onSurfaceChanged</span><span class="pun" style="color: rgb(102, 102, 0);">(</span><span class="pln" style="color: rgb(0, 0, 0);">GL10 unused</span><span class="pun" style="color: rgb(102, 102, 0);">,</span><span class="pln" style="color: rgb(0, 0, 0);"> </span><span class="kwd" style="color: rgb(0, 0, 136);">int</span><span class="pln" style="color: rgb(0, 0, 0);"> width</span><span class="pun" style="color: rgb(102, 102, 0);">,</span><span class="pln" style="color: rgb(0, 0, 0);"> </span><span class="kwd" style="color: rgb(0, 0, 136);">int</span><span class="pln" style="color: rgb(0, 0, 0);"> height</span><span class="pun" style="color: rgb(102, 102, 0);">)</span><span class="pln" style="color: rgb(0, 0, 0);"> </span><span class="pun" style="color: rgb(102, 102, 0);">{</span><span class="pln" style="color: rgb(0, 0, 0);">
        GLES20</span><span class="pun" style="color: rgb(102, 102, 0);">.</span><span class="pln" style="color: rgb(0, 0, 0);">glViewport</span><span class="pun" style="color: rgb(102, 102, 0);">(</span><span class="lit" style="color: rgb(0, 102, 102);">0</span><span class="pun" style="color: rgb(102, 102, 0);">,</span><span class="pln" style="color: rgb(0, 0, 0);"> </span><span class="lit" style="color: rgb(0, 102, 102);">0</span><span class="pun" style="color: rgb(102, 102, 0);">,</span><span class="pln" style="color: rgb(0, 0, 0);"> width</span><span class="pun" style="color: rgb(102, 102, 0);">,</span><span class="pln" style="color: rgb(0, 0, 0);"> height</span><span class="pun" style="color: rgb(102, 102, 0);">);</span><span class="pln" style="color: rgb(0, 0, 0);">
    </span><span class="pun" style="color: rgb(102, 102, 0);">}</span><span class="pln" style="color: rgb(0, 0, 0);">
</span><span class="pun" style="color: rgb(102, 102, 0);">}</span><div class="save_code tracking-ad" data-mod="popu_249" style="position: absolute; height: 60px; right: 30px; top: 5px; color: rgb(255, 255, 255); cursor: pointer; z-index: 2;"><a target=_blank target="_blank" style="color: rgb(51, 102, 153);"><img src="http://static.blog.csdn.net/images/save_snippets.png" style="border: none; max-width: 100%;" alt="" /></a></div>

提示：上面有使用GL10参数，是为了在2.0中简单的复用1.0，从而保持Android代码简洁。

OpenGL ES(1) - 构建OpenGL ES环境

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