Screen space reflections
It is very likely that at one point you will want to render a mesh with reflective qualities. Rendering reflection in 3D is usually a performance-costly task that is limited to planer reflections or environment reflection. Another common reflection restriction is that a scene cannot contain more than one reflective surface at any given time. Both restrictions usually provide an annoying challenge for artists, as they have to take these limitations into account when choosing the materials used in the scene.
Screen space reflection provides an alternative way to support reflection without the previously mentioned restrictions. This technique can be used for any surface shape and it is not restricted to a single surface in a given frame. Although screen space reflections are limited by the lack of information available in screen space, they offer a good alternative in scenes that can't use the traditional reflection methods, as you can see in the following example:
