定义一个三角形
OpenGL ES允许你使用坐标在三维空间中定义一个绘图对象。所以，在定义三角形之前，你需要先定义它的坐标。通常的方法是定义一个顶点坐标数组。为了达到最大效能，你要把坐标写入到ByteBuffer中，它被传递到OpenGL ES图像通道中进行加工。
<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);">Triangle</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);">FloatBuffer</span><span class="pln" style="color: rgb(0, 0, 0);"> vertexBuffer</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);">// number of coordinates per vertex in this array</span><span class="pln" style="color: rgb(0, 0, 0);">
</span><span class="kwd" style="color: rgb(0, 0, 136);">static</span><span class="pln" style="color: rgb(0, 0, 0);"> </span><span class="kwd" style="color: rgb(0, 0, 136);">final</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);"> COORDS_PER_VERTEX </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);">3</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);">static</span><span class="pln" style="color: rgb(0, 0, 0);"> </span><span class="kwd" style="color: rgb(0, 0, 136);">float</span><span class="pln" style="color: rgb(0, 0, 0);"> triangleCoords</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><span class="pln" style="color: rgb(0, 0, 0);"> </span><span class="com" style="color: rgb(136, 0, 0);">// in counterclockwise order:</span><span class="pln" style="color: rgb(0, 0, 0);">
</span><span class="lit" style="color: rgb(0, 102, 102);">0.0f</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);">0.622008459f</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);">0.0f</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);">// top</span><span class="pln" style="color: rgb(0, 0, 0);">
</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="pun" style="color: rgb(102, 102, 0);">-</span><span class="lit" style="color: rgb(0, 102, 102);">0.311004243f</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);">0.0f</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);">// bottom left</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="pun" style="color: rgb(102, 102, 0);">-</span><span class="lit" style="color: rgb(0, 102, 102);">0.311004243f</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);">0.0f</span><span class="pln" style="color: rgb(0, 0, 0);"> </span><span class="com" style="color: rgb(136, 0, 0);">// bottom right</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 color with red, green, blue and alpha (opacity) values</span><span class="pln" style="color: rgb(0, 0, 0);">
</span><span class="kwd" style="color: rgb(0, 0, 136);">float</span><span class="pln" style="color: rgb(0, 0, 0);"> color</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><span class="pln" style="color: rgb(0, 0, 0);"> </span><span class="lit" style="color: rgb(0, 102, 102);">0.63671875f</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);">0.76953125f</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);">0.22265625f</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="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);">Triangle</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);">// initialize vertex byte buffer for shape coordinates</span><span class="pln" style="color: rgb(0, 0, 0);">
</span><span class="typ" style="color: rgb(102, 0, 102);">ByteBuffer</span><span class="pln" style="color: rgb(0, 0, 0);"> bb </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);">ByteBuffer</span><span class="pun" style="color: rgb(102, 102, 0);">.</span><span class="pln" style="color: rgb(0, 0, 0);">allocateDirect</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);">// (number of coordinate values * 4 bytes per float)</span><span class="pln" style="color: rgb(0, 0, 0);">
triangleCoords</span><span class="pun" style="color: rgb(102, 102, 0);">.</span><span class="pln" style="color: rgb(0, 0, 0);">length </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);">4</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);">// use the device hardware's native byte order</span><span class="pln" style="color: rgb(0, 0, 0);">
bb</span><span class="pun" style="color: rgb(102, 102, 0);">.</span><span class="pln" style="color: rgb(0, 0, 0);">order</span><span class="pun" style="color: rgb(102, 102, 0);">(</span><span class="typ" style="color: rgb(102, 0, 102);">ByteOrder</span><span class="pun" style="color: rgb(102, 102, 0);">.</span><span class="pln" style="color: rgb(0, 0, 0);">nativeOrder</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 floating point buffer from the ByteBuffer</span><span class="pln" style="color: rgb(0, 0, 0);">
vertexBuffer </span><span class="pun" style="color: rgb(102, 102, 0);">=</span><span class="pln" style="color: rgb(0, 0, 0);"> bb</span><span class="pun" style="color: rgb(102, 102, 0);">.</span><span class="pln" style="color: rgb(0, 0, 0);">asFloatBuffer</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);">// add the coordinates to the FloatBuffer</span><span class="pln" style="color: rgb(0, 0, 0);">
vertexBuffer</span><span class="pun" style="color: rgb(102, 102, 0);">.</span><span class="pln" style="color: rgb(0, 0, 0);">put</span><span class="pun" style="color: rgb(102, 102, 0);">(</span><span class="pln" style="color: rgb(0, 0, 0);">triangleCoords</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 buffer to read the first coordinate</span><span class="pln" style="color: rgb(0, 0, 0);">
vertexBuffer</span><span class="pun" style="color: rgb(102, 102, 0);">.</span><span class="pln" style="color: rgb(0, 0, 0);">position</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="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>
默认情况下，OpenGL ES假定GLSurfaceView结构的中心为坐标系统的[0,0,0](X,Y,Z)。[1,1,0]就是结构的右上角，[-1,-1,0]是左下角。坐标点是安装逆时针方向绘制的。
定义一个正方形
在OpenGL中定义三角形很容易，但是正方形比较复杂，通常的做法是绘制两个三角形：
为了避免定义两组坐标，你可以使用一个绘制列表来告诉OpenGL ES的绘制顺序：
<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);">Square</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);">FloatBuffer</span><span class="pln" style="color: rgb(0, 0, 0);"> vertexBuffer</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);">ShortBuffer</span><span class="pln" style="color: rgb(0, 0, 0);"> drawListBuffer</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);">// number of coordinates per vertex in this array</span><span class="pln" style="color: rgb(0, 0, 0);">
</span><span class="kwd" style="color: rgb(0, 0, 136);">static</span><span class="pln" style="color: rgb(0, 0, 0);"> </span><span class="kwd" style="color: rgb(0, 0, 136);">final</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);"> COORDS_PER_VERTEX </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);">3</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);">static</span><span class="pln" style="color: rgb(0, 0, 0);"> </span><span class="kwd" style="color: rgb(0, 0, 136);">float</span><span class="pln" style="color: rgb(0, 0, 0);"> squareCoords</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><span class="pln" style="color: rgb(0, 0, 0);"> </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);">0.0f</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);">// top left</span><span class="pln" style="color: rgb(0, 0, 0);">
</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="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);">0.0f</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);">// bottom left</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="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);">0.0f</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);">// bottom right</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);">0.0f</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);">// top right</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="kwd" style="color: rgb(0, 0, 136);">short</span><span class="pln" style="color: rgb(0, 0, 0);"> drawOrder</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><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);"> </span><span class="lit" style="color: rgb(0, 102, 102);">1</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);">2</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);"> </span><span class="lit" style="color: rgb(0, 102, 102);">2</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);">3</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);">// order to draw vertices</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);">Square</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);">// initialize vertex byte buffer for shape coordinates</span><span class="pln" style="color: rgb(0, 0, 0);">
</span><span class="typ" style="color: rgb(102, 0, 102);">ByteBuffer</span><span class="pln" style="color: rgb(0, 0, 0);"> bb </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);">ByteBuffer</span><span class="pun" style="color: rgb(102, 102, 0);">.</span><span class="pln" style="color: rgb(0, 0, 0);">allocateDirect</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);">// (# of coordinate values * 4 bytes per float)</span><span class="pln" style="color: rgb(0, 0, 0);">
squareCoords</span><span class="pun" style="color: rgb(102, 102, 0);">.</span><span class="pln" style="color: rgb(0, 0, 0);">length </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);">4</span><span class="pun" style="color: rgb(102, 102, 0);">);</span><span class="pln" style="color: rgb(0, 0, 0);">
bb</span><span class="pun" style="color: rgb(102, 102, 0);">.</span><span class="pln" style="color: rgb(0, 0, 0);">order</span><span class="pun" style="color: rgb(102, 102, 0);">(</span><span class="typ" style="color: rgb(102, 0, 102);">ByteOrder</span><span class="pun" style="color: rgb(102, 102, 0);">.</span><span class="pln" style="color: rgb(0, 0, 0);">nativeOrder</span><span class="pun" style="color: rgb(102, 102, 0);">());</span><span class="pln" style="color: rgb(0, 0, 0);">
vertexBuffer </span><span class="pun" style="color: rgb(102, 102, 0);">=</span><span class="pln" style="color: rgb(0, 0, 0);"> bb</span><span class="pun" style="color: rgb(102, 102, 0);">.</span><span class="pln" style="color: rgb(0, 0, 0);">asFloatBuffer</span><span class="pun" style="color: rgb(102, 102, 0);">();</span><span class="pln" style="color: rgb(0, 0, 0);">
vertexBuffer</span><span class="pun" style="color: rgb(102, 102, 0);">.</span><span class="pln" style="color: rgb(0, 0, 0);">put</span><span class="pun" style="color: rgb(102, 102, 0);">(</span><span class="pln" style="color: rgb(0, 0, 0);">squareCoords</span><span class="pun" style="color: rgb(102, 102, 0);">);</span><span class="pln" style="color: rgb(0, 0, 0);">
vertexBuffer</span><span class="pun" style="color: rgb(102, 102, 0);">.</span><span class="pln" style="color: rgb(0, 0, 0);">position</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="com" style="color: rgb(136, 0, 0);">// initialize byte buffer for the draw list</span><span class="pln" style="color: rgb(0, 0, 0);">
</span><span class="typ" style="color: rgb(102, 0, 102);">ByteBuffer</span><span class="pln" style="color: rgb(0, 0, 0);"> dlb </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);">ByteBuffer</span><span class="pun" style="color: rgb(102, 102, 0);">.</span><span class="pln" style="color: rgb(0, 0, 0);">allocateDirect</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);">// (# of coordinate values * 2 bytes per short)</span><span class="pln" style="color: rgb(0, 0, 0);">
drawOrder</span><span class="pun" style="color: rgb(102, 102, 0);">.</span><span class="pln" style="color: rgb(0, 0, 0);">length </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);">2</span><span class="pun" style="color: rgb(102, 102, 0);">);</span><span class="pln" style="color: rgb(0, 0, 0);">
dlb</span><span class="pun" style="color: rgb(102, 102, 0);">.</span><span class="pln" style="color: rgb(0, 0, 0);">order</span><span class="pun" style="color: rgb(102, 102, 0);">(</span><span class="typ" style="color: rgb(102, 0, 102);">ByteOrder</span><span class="pun" style="color: rgb(102, 102, 0);">.</span><span class="pln" style="color: rgb(0, 0, 0);">nativeOrder</span><span class="pun" style="color: rgb(102, 102, 0);">());</span><span class="pln" style="color: rgb(0, 0, 0);">
drawListBuffer </span><span class="pun" style="color: rgb(102, 102, 0);">=</span><span class="pln" style="color: rgb(0, 0, 0);"> dlb</span><span class="pun" style="color: rgb(102, 102, 0);">.</span><span class="pln" style="color: rgb(0, 0, 0);">asShortBuffer</span><span class="pun" style="color: rgb(102, 102, 0);">();</span><span class="pln" style="color: rgb(0, 0, 0);">
drawListBuffer</span><span class="pun" style="color: rgb(102, 102, 0);">.</span><span class="pln" style="color: rgb(0, 0, 0);">put</span><span class="pun" style="color: rgb(102, 102, 0);">(</span><span class="pln" style="color: rgb(0, 0, 0);">drawOrder</span><span class="pun" style="color: rgb(102, 102, 0);">);</span><span class="pln" style="color: rgb(0, 0, 0);">
drawListBuffer</span><span class="pun" style="color: rgb(102, 102, 0);">.</span><span class="pln" style="color: rgb(0, 0, 0);">position</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="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>
这个例子告诉你一些绘制复杂图像的方法，通常情况下，你使用多个三角形的集合来绘制其他图像对象。
定义一个三角形
OpenGL ES允许你使用坐标在三维空间中定义一个绘图对象。所以，在定义三角形之前，你需要先定义它的坐标。通常的方法是定义一个顶点坐标数组。为了达到最大效能，你要把坐标写入到ByteBuffer中，它被传递到OpenGL ES图像通道中进行加工。
<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);">Triangle</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);">FloatBuffer</span><span class="pln" style="color: rgb(0, 0, 0);"> vertexBuffer</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);">// number of coordinates per vertex in this array</span><span class="pln" style="color: rgb(0, 0, 0);">
</span><span class="kwd" style="color: rgb(0, 0, 136);">static</span><span class="pln" style="color: rgb(0, 0, 0);"> </span><span class="kwd" style="color: rgb(0, 0, 136);">final</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);"> COORDS_PER_VERTEX </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);">3</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);">static</span><span class="pln" style="color: rgb(0, 0, 0);"> </span><span class="kwd" style="color: rgb(0, 0, 136);">float</span><span class="pln" style="color: rgb(0, 0, 0);"> triangleCoords</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><span class="pln" style="color: rgb(0, 0, 0);"> </span><span class="com" style="color: rgb(136, 0, 0);">// in counterclockwise order:</span><span class="pln" style="color: rgb(0, 0, 0);">
</span><span class="lit" style="color: rgb(0, 102, 102);">0.0f</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);">0.622008459f</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);">0.0f</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);">// top</span><span class="pln" style="color: rgb(0, 0, 0);">
</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="pun" style="color: rgb(102, 102, 0);">-</span><span class="lit" style="color: rgb(0, 102, 102);">0.311004243f</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);">0.0f</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);">// bottom left</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="pun" style="color: rgb(102, 102, 0);">-</span><span class="lit" style="color: rgb(0, 102, 102);">0.311004243f</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);">0.0f</span><span class="pln" style="color: rgb(0, 0, 0);"> </span><span class="com" style="color: rgb(136, 0, 0);">// bottom right</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 color with red, green, blue and alpha (opacity) values</span><span class="pln" style="color: rgb(0, 0, 0);">
</span><span class="kwd" style="color: rgb(0, 0, 136);">float</span><span class="pln" style="color: rgb(0, 0, 0);"> color</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><span class="pln" style="color: rgb(0, 0, 0);"> </span><span class="lit" style="color: rgb(0, 102, 102);">0.63671875f</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);">0.76953125f</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);">0.22265625f</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="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);">Triangle</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);">// initialize vertex byte buffer for shape coordinates</span><span class="pln" style="color: rgb(0, 0, 0);">
</span><span class="typ" style="color: rgb(102, 0, 102);">ByteBuffer</span><span class="pln" style="color: rgb(0, 0, 0);"> bb </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);">ByteBuffer</span><span class="pun" style="color: rgb(102, 102, 0);">.</span><span class="pln" style="color: rgb(0, 0, 0);">allocateDirect</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);">// (number of coordinate values * 4 bytes per float)</span><span class="pln" style="color: rgb(0, 0, 0);">
triangleCoords</span><span class="pun" style="color: rgb(102, 102, 0);">.</span><span class="pln" style="color: rgb(0, 0, 0);">length </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);">4</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);">// use the device hardware's native byte order</span><span class="pln" style="color: rgb(0, 0, 0);">
bb</span><span class="pun" style="color: rgb(102, 102, 0);">.</span><span class="pln" style="color: rgb(0, 0, 0);">order</span><span class="pun" style="color: rgb(102, 102, 0);">(</span><span class="typ" style="color: rgb(102, 0, 102);">ByteOrder</span><span class="pun" style="color: rgb(102, 102, 0);">.</span><span class="pln" style="color: rgb(0, 0, 0);">nativeOrder</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 floating point buffer from the ByteBuffer</span><span class="pln" style="color: rgb(0, 0, 0);">
vertexBuffer </span><span class="pun" style="color: rgb(102, 102, 0);">=</span><span class="pln" style="color: rgb(0, 0, 0);"> bb</span><span class="pun" style="color: rgb(102, 102, 0);">.</span><span class="pln" style="color: rgb(0, 0, 0);">asFloatBuffer</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);">// add the coordinates to the FloatBuffer</span><span class="pln" style="color: rgb(0, 0, 0);">
vertexBuffer</span><span class="pun" style="color: rgb(102, 102, 0);">.</span><span class="pln" style="color: rgb(0, 0, 0);">put</span><span class="pun" style="color: rgb(102, 102, 0);">(</span><span class="pln" style="color: rgb(0, 0, 0);">triangleCoords</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 buffer to read the first coordinate</span><span class="pln" style="color: rgb(0, 0, 0);">
vertexBuffer</span><span class="pun" style="color: rgb(102, 102, 0);">.</span><span class="pln" style="color: rgb(0, 0, 0);">position</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="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>
默认情况下，OpenGL ES假定GLSurfaceView结构的中心为坐标系统的[0,0,0](X,Y,Z)。[1,1,0]就是结构的右上角，[-1,-1,0]是左下角。坐标点是安装逆时针方向绘制的。
定义一个正方形
在OpenGL中定义三角形很容易，但是正方形比较复杂，通常的做法是绘制两个三角形：
为了避免定义两组坐标，你可以使用一个绘制列表来告诉OpenGL ES的绘制顺序：
<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);">Square</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);">FloatBuffer</span><span class="pln" style="color: rgb(0, 0, 0);"> vertexBuffer</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);">ShortBuffer</span><span class="pln" style="color: rgb(0, 0, 0);"> drawListBuffer</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);">// number of coordinates per vertex in this array</span><span class="pln" style="color: rgb(0, 0, 0);">
</span><span class="kwd" style="color: rgb(0, 0, 136);">static</span><span class="pln" style="color: rgb(0, 0, 0);"> </span><span class="kwd" style="color: rgb(0, 0, 136);">final</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);"> COORDS_PER_VERTEX </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);">3</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);">static</span><span class="pln" style="color: rgb(0, 0, 0);"> </span><span class="kwd" style="color: rgb(0, 0, 136);">float</span><span class="pln" style="color: rgb(0, 0, 0);"> squareCoords</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><span class="pln" style="color: rgb(0, 0, 0);"> </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);">0.0f</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);">// top left</span><span class="pln" style="color: rgb(0, 0, 0);">
</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="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);">0.0f</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);">// bottom left</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="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);">0.0f</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);">// bottom right</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);">0.0f</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);">// top right</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="kwd" style="color: rgb(0, 0, 136);">short</span><span class="pln" style="color: rgb(0, 0, 0);"> drawOrder</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><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);"> </span><span class="lit" style="color: rgb(0, 102, 102);">1</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);">2</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);"> </span><span class="lit" style="color: rgb(0, 102, 102);">2</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);">3</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);">// order to draw vertices</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);">Square</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);">// initialize vertex byte buffer for shape coordinates</span><span class="pln" style="color: rgb(0, 0, 0);">
</span><span class="typ" style="color: rgb(102, 0, 102);">ByteBuffer</span><span class="pln" style="color: rgb(0, 0, 0);"> bb </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);">ByteBuffer</span><span class="pun" style="color: rgb(102, 102, 0);">.</span><span class="pln" style="color: rgb(0, 0, 0);">allocateDirect</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);">// (# of coordinate values * 4 bytes per float)</span><span class="pln" style="color: rgb(0, 0, 0);">
squareCoords</span><span class="pun" style="color: rgb(102, 102, 0);">.</span><span class="pln" style="color: rgb(0, 0, 0);">length </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);">4</span><span class="pun" style="color: rgb(102, 102, 0);">);</span><span class="pln" style="color: rgb(0, 0, 0);">
bb</span><span class="pun" style="color: rgb(102, 102, 0);">.</span><span class="pln" style="color: rgb(0, 0, 0);">order</span><span class="pun" style="color: rgb(102, 102, 0);">(</span><span class="typ" style="color: rgb(102, 0, 102);">ByteOrder</span><span class="pun" style="color: rgb(102, 102, 0);">.</span><span class="pln" style="color: rgb(0, 0, 0);">nativeOrder</span><span class="pun" style="color: rgb(102, 102, 0);">());</span><span class="pln" style="color: rgb(0, 0, 0);">
vertexBuffer </span><span class="pun" style="color: rgb(102, 102, 0);">=</span><span class="pln" style="color: rgb(0, 0, 0);"> bb</span><span class="pun" style="color: rgb(102, 102, 0);">.</span><span class="pln" style="color: rgb(0, 0, 0);">asFloatBuffer</span><span class="pun" style="color: rgb(102, 102, 0);">();</span><span class="pln" style="color: rgb(0, 0, 0);">
vertexBuffer</span><span class="pun" style="color: rgb(102, 102, 0);">.</span><span class="pln" style="color: rgb(0, 0, 0);">put</span><span class="pun" style="color: rgb(102, 102, 0);">(</span><span class="pln" style="color: rgb(0, 0, 0);">squareCoords</span><span class="pun" style="color: rgb(102, 102, 0);">);</span><span class="pln" style="color: rgb(0, 0, 0);">
vertexBuffer</span><span class="pun" style="color: rgb(102, 102, 0);">.</span><span class="pln" style="color: rgb(0, 0, 0);">position</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="com" style="color: rgb(136, 0, 0);">// initialize byte buffer for the draw list</span><span class="pln" style="color: rgb(0, 0, 0);">
</span><span class="typ" style="color: rgb(102, 0, 102);">ByteBuffer</span><span class="pln" style="color: rgb(0, 0, 0);"> dlb </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);">ByteBuffer</span><span class="pun" style="color: rgb(102, 102, 0);">.</span><span class="pln" style="color: rgb(0, 0, 0);">allocateDirect</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);">// (# of coordinate values * 2 bytes per short)</span><span class="pln" style="color: rgb(0, 0, 0);">
drawOrder</span><span class="pun" style="color: rgb(102, 102, 0);">.</span><span class="pln" style="color: rgb(0, 0, 0);">length </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);">2</span><span class="pun" style="color: rgb(102, 102, 0);">);</span><span class="pln" style="color: rgb(0, 0, 0);">
dlb</span><span class="pun" style="color: rgb(102, 102, 0);">.</span><span class="pln" style="color: rgb(0, 0, 0);">order</span><span class="pun" style="color: rgb(102, 102, 0);">(</span><span class="typ" style="color: rgb(102, 0, 102);">ByteOrder</span><span class="pun" style="color: rgb(102, 102, 0);">.</span><span class="pln" style="color: rgb(0, 0, 0);">nativeOrder</span><span class="pun" style="color: rgb(102, 102, 0);">());</span><span class="pln" style="color: rgb(0, 0, 0);">
drawListBuffer </span><span class="pun" style="color: rgb(102, 102, 0);">=</span><span class="pln" style="color: rgb(0, 0, 0);"> dlb</span><span class="pun" style="color: rgb(102, 102, 0);">.</span><span class="pln" style="color: rgb(0, 0, 0);">asShortBuffer</span><span class="pun" style="color: rgb(102, 102, 0);">();</span><span class="pln" style="color: rgb(0, 0, 0);">
drawListBuffer</span><span class="pun" style="color: rgb(102, 102, 0);">.</span><span class="pln" style="color: rgb(0, 0, 0);">put</span><span class="pun" style="color: rgb(102, 102, 0);">(</span><span class="pln" style="color: rgb(0, 0, 0);">drawOrder</span><span class="pun" style="color: rgb(102, 102, 0);">);</span><span class="pln" style="color: rgb(0, 0, 0);">
drawListBuffer</span><span class="pun" style="color: rgb(102, 102, 0);">.</span><span class="pln" style="color: rgb(0, 0, 0);">position</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="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>
这个例子告诉你一些绘制复杂图像的方法，通常情况下，你使用多个三角形的集合来绘制其他图像对象。