openGL绘制正方形

/**
* 缓冲区工具类
*/
public class BufferUtil {
/**
* 将浮点数组转换成字节缓冲区
*/
public static ByteBuffer arr2ByteBuffer(float[] arr){
ByteBuffer ibb = ByteBuffer.allocateDirect(arr.length * 4);
ibb.order(ByteOrder.nativeOrder());
FloatBuffer fbb = ibb.asFloatBuffer();
fbb.put(arr);
ibb.position(0);
return ibb ;
}

/**
* 将list转换成字节缓冲区
*/
public static ByteBuffer list2ByteBuffer(List<Float> list){
ByteBuffer ibb = ByteBuffer.allocateDirect(list.size() * 4);
ibb.order(ByteOrder.nativeOrder());
FloatBuffer fbb = ibb.asFloatBuffer();
for(Float f : list){
fbb.put(f);
}
ibb.position(0);
return ibb ;
}
}

/**

* 渲染器

*/

public abstract class AbstractMyRenderer implements android.opengl.GLSurfaceView.Renderer

{

private float ratio;

public float xrotate = 0f;//围绕x轴旋转角度

public float yrotate = 0f;//围绕x轴旋转角度

/**

* 1.

*/

public void onSurfaceCreated(GL10 gl, EGLConfig config)

{

//清平色

gl.glClearColor(0f, 0f, 0f, 1f);

//启用顶点缓冲区数组

gl.glEnableClientState(GL10.GL_VERTEX_ARRAY);

}

/**

* 2.

*/

public void onSurfaceChanged(GL10 gl, int width, int height) {

//设置视口

gl.glViewport(0, 0, width, height);

ratio = (float)width / (float)height;

//投影矩阵

gl.glMatrixMode(GL10.GL_PROJECTION);

//加载单位矩阵

gl.glLoadIdentity();

//设置平截头体

gl.glFrustumf(-ratio, ratio, -1, 1, 3f, 7f); }

/**

* 3.

*/

public abstract void onDrawFrame(GL10 gl);

}

/**
* 三角形带,正方形
*/
public class MyTriangleRenderer extends AbstractMyRenderer{

public void onDrawFrame(GL10 gl) {
//清除颜色缓冲区
gl.glClear(GL10.GL_COLOR_BUFFER_BIT);
//设置绘图颜色
gl.glColor4f(1f, 0f, 0f, 1f);

//操作模型视图矩阵
gl.glMatrixMode(GL10.GL_MODELVIEW);
gl.glLoadIdentity();
//设置眼球的参数
GLU.gluLookAt(gl,0f,0f,5f, 0f, 0f, 0f, 0f,1f,0f);

//旋转角度
gl.glRotatef(xrotate, 1, 0, 0);
gl.glRotatef(yrotate, 0, 1, 0);

//计算点坐标
float r = 0.5f ;//半径
float[] coords = {
-r,r,0,
-r,-r,0,
r,r,0,
r,-r,0,
};
//指定顶点指针
gl.glVertexPointer(3, GL10.GL_FLOAT, 0, BufferUtil.arr2ByteBuffer(coords));
gl.glDrawArrays(GL10.GL_TRIANGLE_STRIP, 0, 4);
}
}

public class MainActivity extends Activity {

private AbstractMyRenderer render;

private MyGLSurfaceView view;

public void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);
view = new GLSurfaceView(this);
render = new MyTriangleRenderer();
view.setRenderer(render);
//GLSurfaceView.RENDERMODE_CONTINUOUSLY:持续渲染(默认)
//GLSurfaceView.RENDERMODE_WHEN_DIRTY:脏渲染,命令渲染
view.setRenderMode(GLSurfaceView.RENDERMODE_WHEN_DIRTY);
setContentView(view);
}

public boolean onKeyDown(int keyCode, KeyEvent event) {

float step = 5f ;
//up
if(keyCode == KeyEvent.KEYCODE_DPAD_UP){
render.xrotate = render.xrotate - step ;
}
else if(keyCode == KeyEvent.KEYCODE_DPAD_DOWN){
render.xrotate = render.xrotate + step ;
}
else if(keyCode == KeyEvent.KEYCODE_DPAD_LEFT){
render.yrotate = render.yrotate + step ;
}
else if(keyCode == KeyEvent.KEYCODE_DPAD_RIGHT){
render.yrotate = render.yrotate - step ;
}
//请求渲染,和脏渲染配合使用
view.requestRender();
return super.onKeyDown(keyCode, event);
}
}