错误/libEGL(206):调用没有当前上下文的OpenGL ES API

Question

我有一个简单的正方形与opengles 1和Android 1.5。正方形被画在屏幕的中央。

我想要当用户在屏幕上按下，或者在屏幕上移动手指时，正方形被移动到那个位置。为此，我尝试了GLuUnProject，我试图获得与手指触摸的窗口XY坐标匹配的opengl坐标(以便在将来将多边形转换为该坐标)，并且我正在LogCat上编写坐标。

我收到的坐标不是真坐标，是错误的坐标，我也得到了问题标题的错误。ERROR/libEGL(206): call to OpenGL ES API with no current context

LogCat:

11-07 09:43:40.012: DEBUG/XXXXXXXXX(203): X: -1.2918732
11-07 09:43:40.023: DEBUG/XXXXXXXXX(203): Y: 0.050911963
11-07 09:43:40.042: ERROR/libEGL(203): call to OpenGL ES API with no current context
11-07 09:43:40.042: ERROR/libEGL(203): call to OpenGL ES API with no current context
11-07 09:43:40.042: DEBUG/XXXXXXXXX(203): X: -1.2943747
11-07 09:43:40.052: DEBUG/XXXXXXXXX(203): Y: 0.04674524
11-07 09:43:40.152: ERROR/libEGL(203): call to OpenGL ES API with no current context
11-07 09:43:40.152: ERROR/libEGL(203): call to OpenGL ES API with no current context
11-07 09:43:40.172: DEBUG/XXXXXXXXX(203): X: 0.77298313
11-07 09:43:40.182: DEBUG/XXXXXXXXX(203): Y: -0.5083332
11-07 09:43:40.223: ERROR/libEGL(203): call to OpenGL ES API with no current context
11-07 09:43:40.223: ERROR/libEGL(203): call to OpenGL ES API with no current context
11-07 09:43:40.223: DEBUG/XXXXXXXXX(203): X: 0.77298313
11-07 09:43:40.223: DEBUG/XXXXXXXXX(203): Y: -0.5083332
11-07 09:43:40.402: ERROR/libEGL(203): call to OpenGL ES API with no current context
11-07 09:43:40.402: ERROR/libEGL(203): call to OpenGL ES API with no current context
11-07 09:43:40.402: DEBUG/XXXXXXXXX(203): X: -1.2943747
11-07 09:43:40.402: DEBUG/XXXXXXXXX(203): Y: 0.04674524
11-07 09:43:41.952: ERROR/libEGL(203): call to OpenGL ES API with no current context
11-07 09:43:41.952: ERROR/libEGL(203): call to OpenGL ES API with no current context
11-07 09:43:41.952: DEBUG/XXXXXXXXX(203): X: 0.77298313
11-07 09:43:41.952: DEBUG/XXXXXXXXX(203): Y: -0.5083332
11-07 09:43:42.042: ERROR/libEGL(203): call to OpenGL ES API with no current context
11-07 09:43:42.042: ERROR/libEGL(203): call to OpenGL ES API with no current context

我代码:

public class MySurfaceView extends GLSurfaceView implements Renderer {  
private float INITIAL_Z = -35.0f;   
private Context context;
private Square square;
private float xrot;                 //X Rotation
private float yrot;                 //Y Rotation
private float zrot;                 //Z Rotation    
private float z = INITIAL_Z;            //Profundidad en el eje Z
private float x = 0.0f;             //eje X
private float y = 0.0f;             //eje Y
private MatrixGrabber mg = new MatrixGrabber(); //create the matrix grabber object in your initialization code    
private GL10 MyGl; //To make gl variable accesible on all the methods of the class
byte horizontal=-1; //0: LEFT  1:CENTER  2:RIGHT
byte vertical=-1; //0: TOP  1:CENTER  2:BOTTOM
float startX=-1;
float startY=-1;
float xMovement=0.0f;
float yMovement=0.0f;
private boolean movement_mode=false;
public MySurfaceView(Context context, Bitmap image, int width, byte horizontal, byte vertical) {
    super(context);
    this.context = context;
    setEGLConfigChooser(8, 8, 8, 8, 16, 0); //fondo transparente
    getHolder().setFormat(PixelFormat.TRANSLUCENT); //fondo transparente
    //Transformamos esta clase en renderizadora
    this.setRenderer(this);
    //Request focus, para que los botones reaccionen
    this.requestFocus();
    this.setFocusableInTouchMode(true);
    square = new Square(image);
    this.horizontal=horizontal;
    this.vertical=vertical;
}
public void onSurfaceCreated(GL10 gl, EGLConfig config) {
    MyGl=gl;
    gl.glDisable(GL10.GL_DITHER);               //dithering OFF
    gl.glEnable(GL10.GL_TEXTURE_2D);            //Texture Mapping ON
    gl.glShadeModel(GL10.GL_SMOOTH);            //Smooth Shading 
    gl.glClearDepthf(1.0f);                     //Depth Buffer Setup
    gl.glEnable(GL10.GL_DEPTH_TEST);            //Depth Testing ON
    gl.glDepthFunc(GL10.GL_LEQUAL);
    gl.glClearColor(0,0,0,0); //fondo transparente
    gl.glHint(GL10.GL_PERSPECTIVE_CORRECTION_HINT, GL10.GL_NICEST);         
    //Cargamos la textura del cubo.
    square.loadGLTexture(gl, this.context);     
}
public void onDrawFrame(GL10 gl) {
    //Limpiamos pantalla y Depth Buffer
    gl.glClear(GL10.GL_COLOR_BUFFER_BIT | GL10.GL_DEPTH_BUFFER_BIT);
    gl.glLoadIdentity();
    //Dibujado
    gl.glTranslatef(x, y, z);           //Move z units into the screen
    //gl.glScalef(0.8f, 0.8f, 0.8f);            //Escalamos para que quepa en la pantalla
    //Rotamos sobre los ejes.
    gl.glRotatef(xrot, 1.0f, 0.0f, 0.0f);   //X
    gl.glRotatef(yrot, 0.0f, 1.0f, 0.0f);   //Y
    gl.glRotatef(zrot, 0.0f, 0.0f, 1.0f);   //Z
    //Dibujamos el cuadrado
    square.draw(gl);    
}
//si el surface cambia, resetea la vista, imagino que esto pasa cuando cambias de modo portrait/landscape o sacas el teclado físico en móviles tipo Droid.
public void onSurfaceChanged(GL10 gl, int width, int height) {
    if(height == 0) {                       
        height = 1;                         
    }
    gl.glViewport(0, 0, width, height);     //Reset Viewport
    gl.glMatrixMode(GL10.GL_PROJECTION);    //Select Projection Matrix
    gl.glLoadIdentity();                    //Reset Projection Matrix
    //Aspect Ratio de la ventana
    GLU.gluPerspective(gl, 45.0f, (float)width / (float)height, 0.1f, 100.0f);
    gl.glMatrixMode(GL10.GL_MODELVIEW);     //Select Modelview Matrix
    gl.glLoadIdentity();                    //Reset Modelview Matrix
}
public boolean onTouchEvent(MotionEvent event) {
    float [] outputCoords=getOpenGLCoords(event.getX(), event.getY(), 0);
    x=(outputCoords[0]/outputCoords[3]);
    y=(outputCoords[1]/outputCoords[3]);
    //z=outputCoords[2]/outputCoords[3];
    Log.d("XXXXXXXXX", "X: "+x);
    Log.d("XXXXXXXXX", "Y: "+y);        
    return true; //El evento ha sido manejado
}
public float[] getOpenGLCoords(float xWin,float yWin,float zWin)
{
    int screenW=SectionManager.instance.getDisplayWidth();
    int screenH=SectionManager.instance.getDisplayHeight();
    //CODE FOR TRANSLATING FROM SCREEN COORDINATES TO OPENGL COORDINATES
    mg.getCurrentProjection(MyGl);
    mg.getCurrentModelView(MyGl);
    float [] modelMatrix = new float[16];
    float [] projMatrix = new float[16];
    modelMatrix=mg.mModelView;
    projMatrix=mg.mProjection;          
    int [] mView = new int[4];
    mView[0] = 0;
    mView[1] = 0;
    mView[2] = screenW; //width
    mView[3] = screenH; //height
    float [] outputCoords = new float[4];
    GLU.gluUnProject(xWin, ((float)screenH)-yWin, zWin, modelMatrix, 0, projMatrix, 0, mView, 0, outputCoords, 0);
    return outputCoords;
}
}

可能重复的注释

我相信这不是其他类似错误的问题的重复，因为在这些问题中，错误的解决方法是有各种线程，有各种线程的问题，但我没有使用各种线程

Answer 1

检查以下两行:

mg.getCurrentProjection(MyGl);
mg.getCurrentModelView(MyGl);

它们在主线程上被调用，而应该在渲染时被调用。你不必存储MyGl属性，因为它只在OpenGL回调(如onDrawFrame(GL10 gl)，你已经有gl变量)中有效。您需要制作类的投影和模型视图矩阵属性，并在每次绘制框架时更新它们(并在需要计算gluUnProject时使用)。

Answer 2

这可能是因为你正在使用GL10实例，我们正在获得的onSurfaceCreated()， onSurfaceChanged()和onDrawFrame()在你的Renderer实现参数。既然你打算使用OpenGL ES 2.0，我们可以也可能不使用实例，而是使用替代方案。还有其他选择!这就是我们在网络上的代码中看到这些参数名称和未使用或类似的原因!