[UE4 Quick Tip] DXT1/DXT5 Normal Maps

By default Unreal Engine 4 uses BC5 compression for normal maps which offers a high level of quality. In case you are fine with some lower quality normals (aka blocky artifacts) you can still use DXT1 compression and therefore save half of the texture memory and 4 shader instructions per material.
Using regular DXT1/DXT5 compression for normal maps also makes it possible to use the blue/alpha channel for storing an additional greyscale texture, e.g. height/displacement maps.


What to do:
1. In the texture properties change the compression setting from TC_NormalMap to TC_Default.
2. In the material, convert your normals from [0...1] to [-1...1] range.