How can I access focal length of active camera, render resolution using animation nodes most directly? I would like to use animation nodes to create edge line meshes for fast edge line rendering-- meshes slightly displaced along their normals, with only backfaces rendered.  To create an edge line that's a single pixel wide, the world-space displacement needs to depend on the camera FoV (focal length + sensor size) as well as the rendering dimensions.

I would like to use animation nodes to do this, as it would simplify the creation of objects and should allow for easy reuse between projects.  I have just started learning animation nodes.

How can I most easily get these numbers into my node trees?  I've tried using object attribute input with a copied data path on my active camera object, but get an "attribute not found".  A copied data path to an expression node for render resolution likewise gives me "name is not defined."  Drivers seem to not be working on float input nodes in animation nodes.  I can create drivers on the positions of empties and access their positions in my node trees, but I'm wondering if there is a more direct way to access this for animation nodes?
I don't know of a way to directly access the current Scene's properties in Animations nodes but you can circumvent that with custom properties
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Add 2 custom properties to your camera and drive them using your resolution. Example with the resolution X :



Now you can access theses properties in AN using an "Attribute Input" node.

Note : To access the "Camera" part of the Camera "Object", the path is obj.data

So : the focal lens is accessed with data.lens