Transform UI Texture Coordinate to scene's clip space


I am trying to transform a World Space Texture Coordinate in a UI material to the scene’s clip space (the VR camera view). The goal is to sample the depth buffer and compare the depth of a stereo layer in order to determine if/where the stereo layer is supposed to be occluded. The TransformToClipSpace node transforms to the render target’s clip space, which is not what I need. Is there a way to get the rendered scene’s clip space from a UI material or from Blueprint, so I can feed it into the material from there?