opencv2/core/core_c.h file not found

I try to add opencv to a project.
I dragged dropped the addons/ofxOpenCv folder to my project.
Now when i compile i get:

“opencv2/core/core_c.h file not found”

I found some answers online but they seem to be outdated. Can someone help?

opencv has some special requirements for search paths. the easiest is to generate the project with the project generator and add the addons from there

I added …/…/…/addons/ofxOpenCv/libs as a recursive search path which seems to work fine.