As a small personal experiment I built a holographic weapon sight in Unreal Engine 4 a while back. Some people were wondering how it was made and it is really quite simple – it all relies on the BumpOffset-node. The material is available for download at the bottom of this page!
To find out more on BumpOffset, the official documentation has some info on How to use Bump Offset. To achieve this effect I sample a texture once for every row of lines, they will all be rendered with a different (incrementally higher) BumpOffset applied.
The material for the 3rd-person survival project:
Impression of the material’s complexity
Package contains two materials with BumpOffset. The first shows the simplest implementation of a single crosshair. The second is a multi-line crosshair with incremental bump applied on each subsequent line.
Use this material as you wish in your UE4 project! If you have another neat trick with BumpOffset, let me know the comment section!