Android Open GL 1.1查看轮换

Question

我对开放式GL的开发相当新。我试图找出如何旋转视图，以便我可以在视图上看到对象的所有边。类似于谷歌地图的旋转方式。有什么建议？这是我目前的代码。

 @Override
public boolean onTouchEvent(MotionEvent e) {
    float x = e.getX();
    float y = e.getY();

    switch (e.getAction() & MotionEvent.ACTION_MASK) {

    case MotionEvent.ACTION_DOWN:
        mode = 0; //safety precaution for screen taps vs swiping
        mPreviousX = x;//safety precaution for screen taps vs swiping
        mPreviousY = y;//safety precaution for screen taps vs swiping

       case MotionEvent.ACTION_POINTER_DOWN:
            if(e.getPointerCount() == 2) {//two fingers down
                oldDist = distance(e);//old distance equals the new distance from the motion event
                mode = 1;
            }
            break;
        case MotionEvent.ACTION_MOVE:
            if (mode == 1) {
                newDist = distance(e);

                if (newDist > oldDist) {     // distance increasing
                    mRenderer.increaseScale(Math.abs(oldDist - newDist) / 100);
                } else if (newDist < oldDist) {   // distance decreasing
                    mRenderer.decreaseScale(Math.abs(oldDist - newDist) / 100);
                }



                //Matrix.rotateM(m, mOffset, a, x, y, z);

                oldDist = newDist;
            } else if(mode == 0) {
                float dx = x - mPreviousX;
                float dy = y - mPreviousY;

                // reverse direction of rotation above the mid-line
                if (y < mView.getHeight() / 2) {
                    dx = dx * -1;
                }

                // reverse direction of rotation to left of the mid-line
                if (x > mView.getWidth() / 2) {
                    dy = dy * -1;
                }

                mRenderer.xAngle += dx * TOUCH_SCALE_FACTOR;
                mRenderer.yAngle += dy * TOUCH_SCALE_FACTOR;

                x = e.getX();
                y = e.getY();

                float distanceX = x - mPreviousX;
                float distanceY = y - mPreviousY;

                mRenderer.moveLeftRight(distanceX/100);
                mRenderer.moveUpDown(distanceY/100);

                mView.requestRender();
                mPreviousX = x;
                mPreviousY = y;
            }
            break;
        case MotionEvent.ACTION_POINTER_UP:
            mode = 0;
            break;
        default:
            super.onTouchEvent(e);
    }
    return true;
}