when I have two (or more) cameras, do they share the same z buffer or do they have their own z buffer ? If I set Clear Flags of the second camera (higher depth) to “Don’t Clear”, can I get the z buffer from the first camera (lower depth) ?
I don’t know about Unity, but in general each camera will have its own z buffer. How the z buffer is updated is dependent on the camera’s transformation, fill mode (solid/wireframe), projection, etc. so it doesn’t make sense to share the z buffer between cameras.
This is a few years late, but for those who stumble by…
The answer is it depends on the targetTexture member of the camera.
You can control each camera’s Render method, and the order in which camera rendering happens by overriding OnRenderImage and scripting the other camera’s render functionality (OR) by setting the depth member in camera to let Unity control the ordering.