MatrixGrabber 的问题：java.lang.ClassCastException：com.google.android.gles_jni.GLImpl

Question

我有一个 GLSurfaceView 类，它必须显示带有纹理的正方形。我试图使屏幕适合纹理/多边形尺寸，然后我需要使用投影。

我使用 3 个类来与 android 1.5 兼容：

MatrixGrabber.java MatrixStack.java MatrixTrackingGL.java

这是给出错误的代码部分：

private MatrixGrabber mg = new MatrixGrabber(); //create the matrix grabber object in your initialization code   
.
.
.
DisplayMetrics dm = new DisplayMetrics();
        ((Activity)context).getWindowManager().getDefaultDisplay().getMetrics(dm);      
        screenW=dm.widthPixels;
        screenH=dm.heightPixels;

        modelMatrix=mg.mModelView;
        projMatrix=mg.mProjection;
        mView[0] = 0;
        mView[1] = 0;
        mView[2] = screenW; //width
        mView[3] = screenH; //height    
.
.
.
public void onDrawFrame(GL10 gl) {      
        //Clear Screen And Depth Buffer
        gl.glClear(GL10.GL_COLOR_BUFFER_BIT | GL10.GL_DEPTH_BUFFER_BIT);    
        gl.glLoadIdentity();                    //Reset The Current Modelview Matrix

        mg.getCurrentProjection(gl);
        mg.getCurrentModelView(gl); 
.
.
.

这是错误：

    02-17 09:13:59.952: WARN/dalvikvm(11405): threadid=8: thread exiting with uncaught exception (group=0x4001d7e0)
02-17 09:13:59.960: ERROR/AndroidRuntime(11405): FATAL EXCEPTION: GLThread 9
02-17 09:13:59.960: ERROR/AndroidRuntime(11405): java.lang.ClassCastException: com.google.android.gles_jni.GLImpl
02-17 09:13:59.960: ERROR/AndroidRuntime(11405):     at com.DemoMagazine.MatrixGrabber.getMatrix(MatrixGrabber.java:56)
02-17 09:13:59.960: ERROR/AndroidRuntime(11405):     at com.DemoMagazine.MatrixGrabber.getCurrentProjection(MatrixGrabber.java:52)
02-17 09:13:59.960: ERROR/AndroidRuntime(11405):     at com.DemoMagazine.SquareGLSurfaceView.onDrawFrame(SquareGLSurfaceView.java:112)
02-17 09:13:59.960: ERROR/AndroidRuntime(11405):     at android.opengl.GLSurfaceView$GLThread.guardedRun(GLSurfaceView.java:1332)
02-17 09:13:59.960: ERROR/AndroidRuntime(11405):     at android.opengl.GLSurfaceView$GLThread.run(GLSurfaceView.java:1116)

Answer 1

我在尝试获取矩阵时也遇到了一些问题，但在您的情况下，它们似乎已修复，将矩阵模式设置为我将要获得的模式：

public void onDrawFrame(GL10 gl) {      
    //Clear Screen And Depth Buffer
    gl.glClear(GL10.GL_COLOR_BUFFER_BIT | GL10.GL_DEPTH_BUFFER_BIT);
    gl.glMatrixMode(GL10.GL_MODELVIEW);
    gl.glLoadIdentity();                    //Reset The Current Modelview Matrix

    mg.getCurrentModelView(gl);
    gl.glMatrixMode(GL10.GL_PROJECTION);
    mg.getCurrentProjection(gl);

并记住您现在处于投影模式，如果需要，您可以去返回模型视图。这对我有用。

问候！