I discovered something while setting my challenge project up for compositing that I think might be very important for people to know: when rendering in Eevee, there is currently no way to mask/holdout any objects in your scene, like you can with Cycles. The Holdout and Indirect Only buttons are still there in the Outliner and are clickable, but they have no effect when Eevee is your engine. I researched to see whether or not this was a bug, but it is not; the functionality is not there. I don’t know if there’s plans to add it in the future or not. Just something to keep in mind!
For anyone not there yet, “holdout” or masking is when one of your objects is set to be invisible but still hide anything behind it in the scene, from the camera’s perspective. It is different from simply being set to not appear in the render; when an object is set as a holdout, it leaves a black hole in the render, in the shape of its silhouette. This is very useful when compositing, if you want to be able to adjust the colors or other material properties of particular objects in a scene independently of the rest of the scene after rendering.
