Depth buffer problem on Samsung Galaxy S2

max111 · by **max111** » Mon Jul 11, 2011 3:33 pm

Hi,

I have a problem with ZBuffer.
On emulator everythink is OK, but on Samsung Galaxy S2 zbuffer is lost between onDrawFrame calls.

Emulator displays first triangle with a hole (other triangle from zbuffer).
On Samsung S2 after a while is only first triangle without any hole (zbuffer is lost).
What is wrong?

Here is my test program:

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package com.mk;
 
import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.nio.FloatBuffer;
import java.nio.ShortBuffer;
 
import javax.microedition.khronos.egl.EGLConfig;
import javax.microedition.khronos.opengles.GL10;
 
import android.app.Activity;
import android.opengl.GLSurfaceView;
import android.opengl.GLSurfaceView.Renderer;
import android.opengl.GLU;
import android.os.Bundle;
import android.util.Log;
import android.view.Window;
import android.view.WindowManager;
 
public class MainActivity extends Activity implements Renderer {
 
        private GLSurfaceView glView;
 
        @Override
        public void onCreate(Bundle savedInstanceState) {
                super.onCreate(savedInstanceState);
 
                this.requestWindowFeature(Window.FEATURE_NO_TITLE);
                getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
                                WindowManager.LayoutParams.FLAG_FULLSCREEN);
 
                glView = new GLSurfaceView(this);
                glView.setRenderer(this);
                setContentView(glView);
        }
 
        private final static int VERTS = 3;
        private static FloatBuffer mVerticesTriangleFar;
        private static FloatBuffer mVerticesTriangleNear;
        private static ShortBuffer mIndicesBuffer;
 
        private static float[] triangle_far = { 
                -0.5f, -0.5f, 0.5f, 
                0.5f, -0.5f, 0.5f,
                -0.0f, 0.5f, 0.5f };
 
        private static float[] triangle_near = { 
                -0.2f, -0.2f, 0.2f, 
                0.2f, -0.2f, 0.2f,
                -0.0f, 0.2f, 0.2f };
 
        private static short[] indices = { 0, 1, 2 };
 
        static {
                ByteBuffer byteBuf = ByteBuffer.allocateDirect(VERTS * 3 * 4);
                byteBuf.order(ByteOrder.nativeOrder());
                mVerticesTriangleFar = byteBuf.asFloatBuffer();
 
                byteBuf = ByteBuffer.allocateDirect(VERTS * 3 * 4);
                byteBuf.order(ByteOrder.nativeOrder());
                mVerticesTriangleNear = byteBuf.asFloatBuffer();
 
                ByteBuffer ibb = ByteBuffer.allocateDirect(VERTS * 2);
                ibb.order(ByteOrder.nativeOrder());
                mIndicesBuffer = ibb.asShortBuffer();
 
                for (int i = 0; i < VERTS; i++)
                        for (int j = 0; j < 3; j++)
                                mVerticesTriangleFar.put(triangle_far[i * 3 + j]);
 
                for (int i = 0; i < VERTS; i++)
                        for (int j = 0; j < 3; j++)
                                mVerticesTriangleNear.put(triangle_near[i * 3 + j]);
 
                for (int i = 0; i < VERTS; i++)
                        mIndicesBuffer.put(indices[i]);
 
                mVerticesTriangleFar.position(0);
                mVerticesTriangleNear.position(0);
                mIndicesBuffer.position(0);
 
        }
 
        private int ile = 1;
 
        @Override
        public void onDrawFrame(GL10 gl) {
                gl.glMatrixMode(GL10.GL_MODELVIEW);
                gl.glLoadIdentity();
                GLU.gluLookAt(gl, 0, 0, -5, 0, 0, 0, 0, 1f, 0);
 
                if (ile < 120) {
                        //near triangle to zbuffer
                        gl.glClear(GL10.GL_DEPTH_BUFFER_BIT);
                        gl.glEnableClientState(GL10.GL_VERTEX_ARRAY);
                        gl.glVertexPointer(3, GL10.GL_FLOAT, 0, mVerticesTriangleNear);
                        gl.glDrawElements(GL10.GL_TRIANGLES, VERTS, GL10.GL_UNSIGNED_SHORT,
                                        mIndicesBuffer);
                        
                        ile ++;
                }
                Log.d("MK", "ile = " + ile);
                
 
                gl.glClear(GL10.GL_COLOR_BUFFER_BIT);
 
                //far triangle
 
                gl.glColor4f(1.0f, 1.0f, 0f, 0.5f);
                gl.glEnableClientState(GL10.GL_VERTEX_ARRAY);
                gl.glVertexPointer(3, GL10.GL_FLOAT, 0, mVerticesTriangleFar);
                gl.glDrawElements(GL10.GL_TRIANGLES, VERTS, GL10.GL_UNSIGNED_SHORT,
                                mIndicesBuffer);
        }
 
        @Override
        public void onSurfaceChanged(GL10 gl, int width, int height) {
                gl.glViewport(0, 0, width, height);
                float ratio = (float) width / height;
                gl.glMatrixMode(GL10.GL_PROJECTION);
                gl.glLoadIdentity();
                gl.glFrustumf(-ratio, ratio, -1, 1, 3, 7);
        }
 
        @Override
        public void onSurfaceCreated(GL10 gl, EGLConfig config) {
                gl.glClearColor(0.5f, 0.5f, 0.5f, 1.0f);
                
                gl.glClearDepthf(1.0f);
                gl.glDepthFunc(GL10.GL_LEQUAL);
                gl.glEnable(GL10.GL_DEPTH_TEST);
                gl.glDepthMask(true);
                gl.glClear(GL10.GL_DEPTH_BUFFER_BIT);
        }
 
        @Override
        protected void onResume() {
                super.onResume();
                glView.onResume();
        }
 
        @Override
        protected void onPause() {
                super.onPause();
                glView.onPause();
        }
 
}
 
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Ghost · by **Ghost** » Mon Jul 11, 2011 6:25 pm

Sorry for posting without having an answer, but can I ask why don't you just use something like this:

Code: Select all: gl.glClear(GL10.GL_COLOR_BUFFER_BIT | GL10.GL_DEPTH_BUFFER_BIT);

at the beginning of your onDrawFrame method?

And also it appears to me, that you clear ZBuffer only first 120 times. Though I'm not sure if it has anything to do with the problem.

max111 · by **max111** » Mon Jul 11, 2011 9:34 pm

This is only a test program, "120" is random value to show a problem.
In my destination program (2.5d technique) I have a static 3d scene and I want to set my zbuffer only once (in the first onDrawFrame calling) - for example:

private boolean firstTime = true;
...
@Override
public void onDrawFrame(GL10 gl) {
...
if (firstTime) {
firstTime = false;
//fill z-buffer
}
...
}

Ghost · by **Ghost** » Wed Jul 13, 2011 7:42 am

Have you found an answer yet?
If you want, you could upload your demo solution, so I could try to run it on my xperia. Maybe something will work out.

Depth buffer problem on Samsung Galaxy S2

Depth buffer problem on Samsung Galaxy S2

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Re: Depth buffer problem on Samsung Galaxy S2

Re: Depth buffer problem on Samsung Galaxy S2

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