* I have already several depth buffers (see my first post).
Anything you had attached to GL_COLOR_ATTACHMENTi are used for your purposes (but for OpenGL they are notified as color buffer) and they are not reacting with depth buffer...
* What OpenGL will write in GL_DEPTH_ATTACHMENT ? A common depth buffer will be wrote for all vertex emitted by the geometry shader ?
If your FBO doesn't have something attached into GL_DEPTH_ATTACHMENT OpenGL can't do any operations with depth buffer because it doesn't exist. A common (screen) depth buffer will not be touched till you are working with your FBO.
So, you need to attach something into GL_DEPTH_ATTACHMENT (texture or render buffer) and do it (what you want) in multi-pass or...
you can attach large depth texture (internal format: GL_DEPTH_COMPONENT) which would contain a couple of textures (which you planned to make them with separated "depth" textures):
+---+
|012|
|345|
+---+
each number - area of depth buffer which is used for something, for your purposes (in fragment shader you need to do custom clipping).
Best wishes, FXACE.
