Following instructions from here:
http://en.esotericsoftware.com/spine-ue4
note there is a typo:
Create a new empty code project in the Unreal Engine Editor. You can use either C++ or Blueprints to work with the spine-ue4 runtime, put the plugin requires a code project.
should say "BUT the plugin requires a C++ project".
It's not clear how you would use this without a C++ project, but anyway, neither these instructions, nor the demo project, will compile the plugin.
Severity Code Description Project File Line Suppression State
Error C1083 Cannot open include file: 'spine/spine.h': No such file or directory SpineUE4 C:\Users\user\Desktop\spine-ue4\Plugins\SpinePlugin\Source\SpinePlugin\Public\SpineSkeletonDataAsset.h 34
Severity Code Description Project File Line Suppression State
Error C1083 Cannot open include file: 'spine/spine.h': No such file or directory SpineUE4 C:\Users\user\Desktop\spine-ue4\Plugins\SpinePlugin\Source\SpinePlugin\Public\SpineAtlasAsset.h 34
Clone of github is same issue
