[Slackbuilds-users] frei0r slackbuild issue with opencv4

[Tim Dickson]

frei0r slackbuild is failing to build with opencv (4) giving the 
following...

CMake Error: The following variables are used in this project, but they 
are set to NOTFOUND.
Please set them or make sure they are set and tested correctly in the 
CMake files:
OpenCV_INCLUDE_DIR

I have tried adding
OpenCV_INCLUDE_DIR=/usr/include/opencv4/opencv2; export OpenCV_INCLUDE_DIR
to the build script before the cmake line build it still says it can't 
find it even those those directories are ok.
any ideas?
regards, Tim