There is BoundingBox.intersect

But I gather you want to be more precise than so. So it will cost to calculate intersections for many Groups however you do it.

You don't mention if is this is on 1 plane or 3d.

Thanks , TIG and Dan, I have decided to install Ruby, though it seem a little complex to me

thanks TIG, I worked it out by classify_point and raytest

You could perhaps do a simplified version and map the boundingbox of the groups to a cached array, then use Geom.point_in_polygon_2D to see if any of the points are within the selectionbox of your custom tool. It will miss the cases where a selectionbox crosses the group's boundingbox but the corner points are outside, but if you start to do intersection on all that you might very well end up with a sluggish tool. Might be good enough?

There are already several Ruby bindings written for curl.

Maybe one could be made to work under SketchUp ??

Important note: If you apply a transformation to entities that are not in the current edit context (i.e. faces that are inside a group), SketchUp will apply the transformation incorrectly, since the geometry has one origin and the current edit context has another. You can correct for this by watching the Model.edit_transform and Model.active_path. See ModelObserver.onActivePathChanged for more information.

I put it in the origin and tried, there still is a problem ,the side face of the tube come out of the group(component) with the top and bottom face being still in the group

thank you,
yes you are right, I used ASP grammar here:(
but I find I also used wrong database driver provider, anyway ,I have worked it out.