glCheckFramebufferStatus returns 36054 GL_FRAMEBUFFER_INCOMPLETE_ATTACHMENT

Question

This is just to share something that took me a long time to figure out. If you don't need your Depthbuffer or don't have a Depth Buffer Attachment Point setup in EGL this might help.

For some reason I couldn't get rendering to texture to work setting the render buffer object RBO to depth buffer: like so

    GLES20.glFramebufferTexture2D(GLES20.GL_FRAMEBUFFER, 
            GLES20.GL_COLOR_ATTACHMENT0, GLES20.GL_TEXTURE_2D, 
            juliaTex[0], 0);
    rain.checkGlError("glFramebufferTexture2D");
    GLES20.glFramebufferRenderbuffer(GLES20.GL_FRAMEBUFFER, 
            GLES20.GL_DEPTH_ATTACHMENT, GLES20.GL_RENDERBUFFER, 
            juliaRBO[0]);
    rain.checkGlError("glFramebufferRenderbuffer");

    int status = GLES20.glCheckFramebufferStatus(GLES20.GL_FRAMEBUFFER);

Causes error status == GLES20.GL_FRAMEBUFFER_INCOMPLETE_ATTACHMENT

If I change render buffer storage to GLES20.GL_RGBA4, as opposed to GLES20.DEPTH_COMPONENT16 and change GLES20.GL_DEPTH_ATTACHMENT to GLES20.GL_COLOR_ATTACHMENT0 then the error goes away,

Change this

    // create render buffer and bind 16-bit depth buffer
    GLES20.glBindRenderbuffer(GLES20.GL_RENDERBUFFER, juliaRBO[0]);
    rain.checkGlError("glBindRenderBuffer");
    GLES20.glRenderbufferStorage(GLES20.GL_RENDERBUFFER, GLES20.DEPTH_COMPONENT16, 
            rain.width, rain.height);

to this

    // create render buffer and bind 16-bit depth buffer
    GLES20.glBindRenderbuffer(GLES20.GL_RENDERBUFFER, juliaRBO[0]);
    rain.checkGlError("glBindRenderBuffer");
    GLES20.glRenderbufferStorage(GLES20.GL_RENDERBUFFER, GLES20.GL_RGBA4, 
            rain.width, rain.height);

And the original code to this:

    GLES20.glFramebufferTexture2D(GLES20.GL_FRAMEBUFFER, 
            GLES20.GL_COLOR_ATTACHMENT0, GLES20.GL_TEXTURE_2D, 
            juliaTex[0], 0);
    rain.checkGlError("glFramebufferTexture2D");
    GLES20.glFramebufferRenderbuffer(GLES20.GL_FRAMEBUFFER, 
            GLES20.GL_COLOR_ATTACHMENT0, GLES20.GL_RENDERBUFFER, 
            juliaRBO[0]);
    rain.checkGlError("glFramebufferRenderbuffer");

then status == GLES20.GL_FRAMEBUFFER_COMPLETE

But the texture is empty.

here is the call to create storage texture

    // bind texture
    GLES20.glBindTexture(GLES20.GL_TEXTURE_2D, juliaTex[0]);

    // clamp texture to edges
    GLES20.glTexParameteri(GLES20.GL_TEXTURE_2D, GLES20.GL_TEXTURE_WRAP_S,
            GLES20.GL_CLAMP_TO_EDGE);
    GLES20.glTexParameteri(GLES20.GL_TEXTURE_2D, GLES20.GL_TEXTURE_WRAP_T,
            GLES20.GL_CLAMP_TO_EDGE);
    GLES20.glTexParameteri(GLES20.GL_TEXTURE_2D, GLES20.GL_TEXTURE_MAG_FILTER,
            GLES20.GL_LINEAR);
    GLES20.glTexParameteri(GLES20.GL_TEXTURE_2D, GLES20.GL_TEXTURE_MIN_FILTER,
            GLES20.GL_LINEAR);
    rain.checkGlError("glTexParameter JuliaTex");

    // create it
    /*
    int[] buf = new int[rain.width * rain.height];
    juliaTexBuff = ByteBuffer.allocateDirect(buf.length
            * rain.FLOAT_SIZE_BYTES).order(ByteOrder.nativeOrder()).asIntBuffer();
     */
    // generate the textures
    GLES20.glTexImage2D(GLES20.GL_TEXTURE_2D, 0, GLES20.GL_RGBA, 
            rain.width, rain.height, 0, GLES20.GL_RGBA, 
            GLES20.GL_UNSIGNED_SHORT_4_4_4_4, null);

Answer 1

To get this to work in addition to attaching the render buffer to the color attachment point I swapped the order of the Framebuffer attachments:

    GLES20.glFramebufferRenderbuffer(GLES20.GL_FRAMEBUFFER, 
            GLES20.GL_COLOR_ATTACHMENT0, GLES20.GL_RENDERBUFFER, 
            juliaRBO[0]);
    rain.checkGlError("glFramebufferRenderbuffer");
    GLES20.glFramebufferTexture2D(GLES20.GL_FRAMEBUFFER, 
            GLES20.GL_COLOR_ATTACHMENT0, GLES20.GL_TEXTURE_2D, 
            juliaTex[0], 0);
    rain.checkGlError("glFramebufferTexture2D");

So that Texture2D is attached to the Framebuffer color layer after Renderbuffer. I assume the last connection point is the point OpenGL ES uses.