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OpenGl绘制螺旋线
/**
* 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);
}
/**
* 线代,依次相连,不闭合
*/
public class MyLineStripRenderer 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
List<Float> coordsList = new ArrayList<Float>();
float x = 0f,y = 0f,z = 1f ;
float zstep = 0.005f ;
for(float alpha = 0f ; alpha < Math.PI * 6 ; alpha = (float) (alpha + Math.PI / 32)){
x = (float) (r * Math.cos(alpha));
y = (float) (r * Math.sin(alpha));
z = z - zstep ;
coordsList.add(x);
coordsList.add(y);
coordsList.add(z);
}
//指定顶点指针
gl.glVertexPointer(3, GL10.GL_FLOAT, 0, BufferUtil.list2ByteBuffer(coordsList));
gl.glDrawArrays(GL10.GL_LINE_STRIP, 0, coordsList.size() / 3);
}
}
//主界面
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 MyLineStripRenderer();
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);
}
}