Android OpenGL ES 2.0 multible对象

Question

We use Opengl ES 2.0 for android and are trying to display two Cubes stacked on each other. For that we have two vertexbuffers (mCubePositions1 and mCubePositions2) which store the Cubedata (the vertices combined to triangles) and call a seperate draw method for each of them:

    GLES20.glVertexAttribPointer(mPositionHandle, mPositionDataSize, GLES20.GL_FLOAT, false,0, mCubePositions1); //the second time mCubePositions2
    GLES20.glEnableVertexAttribArray(mPositionHandle);
    //some Code concerning lightning and textures
    GLES20.glDrawArrays(GLES20.GL_TRIANGLES, 0, 36);

The result is two cubes are displayed, but if we let them rotate, the cube which is drawn second is always displayed on top (2nd Cube is shining through the 1st). In the onSurfaceCreated method we initialise the depth-buffer:

    // Set the background clear color to black.
    GLES20.glClearColor(0.0f, 0.0f, 0.0f, 0.0f);
    GLES20.glClearDepthf(1.0f);
    // Use culling to remove back faces.
    GLES20.glEnable(GLES20.GL_CULL_FACE);
    // Enable depth testing
    GLES20.glEnable(GLES20.GL_DEPTH_TEST);
    GLES20.glDepthFunc(GLES20.GL_LEQUAL);
    GLES20.glDepthMask(true);

There is a solution combining the two buffers into one and than calling just one draw-method, but this is not a solution for us, because we want to move the Cubes seperatly.

If this is not enougth code to answer please ask for more.

Thank you for every answer :)

Answer 1

If you enable depth testing, and it still does not work, this typically means that you don't have a depth buffer.

When using a GLSurfaceView in Android, you request what buffers you need while the view is initialized, by calling the setEGLConfigChooser method. There are a few overloads for this method. The most commonly used one takes a size (number of bits) for each buffer. A typical call will look like this:

setEGLConfigChooser(8, 8, 8, 0, 16, 0);

This means that you want 8 bits each for RGB, do not require alpha, want a 16-bit depth buffer, and do not need stencil.

Note that it is not guaranteed that you will get exactly the specified sizes, but the best possible match among the available configurations.