On Mon, 2008-08-11 at 11:32 +0100, Øyvind Kolås wrote: > On Mon, Aug 11, 2008 at 11:03 AM, Murray Cumming <[EMAIL PROTECTED]> wrote: > > I have sometimes thought that it would be a nice abstraction to put an > > actor on a rail and let the user move it along that rail. > > > > Does clutter-box2d offer anything like that, or could it? > > There are multiple ways you could do this. By creating some actors in > a box2d group that will not be visualized but only used for the > physics simulation. The elastomanic approach would be to create a > railing and then a "wagon" that drives the rail with wheels/sledges on > both sides of the railing that are held together by an elastic joint > making it snugly hug the railing. Ideally you probably would want to > use circular shapes for wheels, but ClutterBox2d is currently only > mirroring the bounding boxes of actors making you have to stick with > rectangles for now. > > ___ _____ > | | | > | |_|_| | > |=======|=======\ | > | | | | \ | > |___| \ / > \_____/ > > > It would also be possible to do it with only one wheel, where you > create a hollow railing. > > For both of these you might have to do some additional tweaking of how > the pointer events manipulate the actors since you might want a larger > grabbable region than the underlying mechanics would provide. Note > that all of this mechanics might be placed in actors that are > hidden/have 0 opacity.
Many thanks for thinking about it. But I guess this would be a rather inefficient way of getting this behaviour, as well as being lengthy to implement. I guess this is something that could be abstracted outside of clutter-box2d, though it would be nice to still use the hitting and damping stuff from clutter-box22d. -- [EMAIL PROTECTED] www.murrayc.com www.openismus.com -- To unsubscribe send a mail to [EMAIL PROTECTED]
