1. Create FBO & its textures like normal.

        // FBO & Texture
        glGenFramebuffers(1, &mFbo);
        glBindFramebuffer(GL_FRAMEBUFFER, mFbo);
        glGenTextures(2, mTexture);

        for(int i=0; i<2; i++)
        {
            // Init texture
            glBindTexture(GL_TEXTURE_2D, mTexture[i]);
            glTexImage2D( GL_TEXTURE_2D, 0, GL_RGBA, SCREEN_W, SCREEN_H, \
                0, GL_RGBA, GL_UNSIGNED_BYTE, 0 );
            glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE );
            glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE );
            glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR );
            glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR );
            glBindTexture( GL_TEXTURE_2D, 0 );

            // attach to FBO
            glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0+i, GL_TEXTURE_2D, \
                mTexture[i], 0);
        }
        glBindFramebuffer( GL_FRAMEBUFFER, 0 );
        glUseProgram(0);

 2. Bind FBO and render it inside draw loop.

        // Preparing FBO texture.
        glBindFramebuffer(GL_FRAMEBUFFER, mFbo);
        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

        GLuint at0[1] =  {GL_COLOR_ATTACHMENT0};
        GLuint at1[1] = {GL_COLOR_ATTACHMENT0+1};

        glDrawBuffers(1, at0);
        // Filled texture attachment0 less white (transparency = 0.5f)
        GUtils::VideoDriver::GetInstance()->DrawFillRect(glm::vec2(0,0), \
                SCREEN_W, SCREEN_H, glm::vec4(glm::vec3(1.0f/(1)), 0.5f));

        glDrawBuffers(1, at1);
        // Filled texture attachment0+1 white.
        GUtils::VideoDriver::GetInstance()->DrawFillRect(glm::vec2(0,0), \
                SCREEN_W, SCREEN_H, glm::vec4(glm::vec3(1.0f/(1)), 1.0f));

        glBindFramebuffer(GL_FRAMEBUFFER, 0);

After all things I did above:

 - texture attachment0 (mTexture[0]) will be filled in less white.
 - texture attachment1 (mTexture[1]) will be filled in white.

**Right?**

I cannot understand when render FBO texture:

    glBindTexture(GL_TEXTURE_2D, mTexture[index]);
    glDrawElements( GL_TRIANGLES, 6, GL_UNSIGNED_INT, 0 );
    glBindTexture(GL_TEXTURE_2D, 0);

 1. mTexture[0] , screen = **white**. (It must be **less White**)
 2. mTexture[1] , screen = **black**. (It must be **White**)

Why this happens?

How can I fix this?