With the correct imports, yes. You’d need to import all the headers correctly and optionally preface them correctly, like cv::Point2f (unless you imported the entire namespace, which you probably shouldn’t do). You might want to check out ofxCv: https://github.com/kylemcdonald/ofxCv that makes it easier to work with native OpenCV types.
no, we don’t include any of the image decoder librares with opencv cause we already include them with openframeworks and they would clash when compiling both together. if you need to load an image you can use ofImage and then turn that into an opencv Mat using ofxCv::toCv, like:
ofImage ofimg; ofimg.load("someimage.png"); cv::Mat img = ofxCv::toCv(ofimg);