Also tested here on the 2020308 tarball and used the 6 plugins with expected results. Although I did not time it, most likely it built faster which is beneficial -- only using the plugins anyway. Will check in to GIT next time boot the desktop. (Andrew, it must have been quite a challenge to determine which modules of OpenCV actually contained the plugins!).
well, it started to fail after I left only core stuff, so I looked at exact missing includes like this, on tablet:
grep video.hpp -r plugins/ plugins/stylizeobj/stylizeobj.h:#include "opencv2/video/video.hpp" plugins/puzzleobj/puzzleobj.h:#include "opencv2/video/video.hpp" plugins/moveobj/moveobj.h:#include "opencv2/video/video.hpp" plugins/gaborobj/gaborobj.h:#include "opencv2/video/video.hpp" plugins/flowobj/flowobj.h:#include "opencv2/video/video.hpp"
and then I looked inside each include with mcedit and augmented my list until it all was at least building again.
Problem is - dynamic build does not install opencv shared libraries (may be due to danger of overwriting system components) so this mode does not work out of the box ....
So, I left it alone for now.
I did not get the downloaded 4.8.0 opencv to work, but I did not try very hard. I did try to peruse the Changelog for OpenCV and found no obvious changes listed for the 6 plugins although I could have missed it. I have to start testing the HDR patches that Andrea has been testing.
Hopefully I get them right! Builds with opencv4 (2020 tarball) on Slackware -current x86_64
hopefully will make compile farm's job a bit easier.
Note, I only modded and tested local static build, you can try to add similar line (with closing "\" !) to second, dynamic case in opencv_build file in root of cingg source tree.