I'm struggling with this issue for some time and yet to find a solution.
ol3 supplies the method forEachFeatureIntersectingExtent which only good for boxes.

I have user drawn polygons (or multipolygons) for selecting features from a vector layer.
I'm relatively new to openlayers and chose to start developing a new project with ol3.

I know openlayers 2 had intersect functions for geometries not just for extents and will greatly appreciate help understanding how to achieve this with ol3.