Question

I made an Android App in which I render everything with OpenGL-ES 2.0 and C++ over JNI and it all works fine except for one thing. It seems as if the Renderbuffers somehow get out of order and the image looks like its trailing a shadow. Somehow like motion blur and I don’t know whats causing this.

I only create an Activity with a GLSurfaceView that has a Renderer class in which the render calls for drawing are. What could be causing this strange behaviour ?

The Java code (minus some irrelevant things) that creates all things looks like this:

public class Main extends Activity  
{   static  MainLoop    mloop   = null;

    @Override
    protected void onCreate(Bundle savedInstanceState) 
    {   super.onCreate(savedInstanceState);
        mloop = new MainLoop()
        setContentView(mloop);
    }
    .
    .
    .
}

The Java code that renders looks like this (again minus some irrelevant things):

public class MainLoop extends GLSurfaceView
{   .
    .
    public MainLoop()
    {   super(parent);
        setEGLContextClientVersion(2);
        setEGLConfigChooser(8, 8, 8, 8, 0, 0)
        //
        this.getHolder().setFormat(PixelFormat.TRANSLUCENT);
        //
        setRenderer(new Renderer());        
    }
    .
    .

    private static class Renderer implements GLSurfaceView.Renderer 
    {   public void onDrawFrame(GL10 gl)
        {   JNIRender();
        }
        public void onSurfaceChanged(GL10 gl, int width, int height)
        {   JNIChanged();   
        }
        public void onSurfaceCreated(GL10 gl, EGLConfig config)
        {   JNICreate();
        }
    }
}

The whole rendering is done with the JNIRender call in C++ and looks fine except for the out-of-order thing where all looks as if its trailing a shadow. Is there something I have to take into account or that I am doing wrong ?

Answer 1

I checked and found that I have a swapbuffer command in my c++ code which is bad when used in java because the buffer is being displayed automatically anyway and this confuses things.

I encased my swapbuffer command in an ifdef that its never being used when compiling with the gcc.