Hi Julian, thankyou very much for the reply and the level of detail provided. Much appreciated.
So if my instance is a sphere it should work shouldn't it? I will have another look at my ICE setup to see what I'm missing. Good to know that other shapes won't work, makes sense now that you've explained it. Will also have a play with relaxation techniques, though I think the sheer volume of instances I have will break my machine. (Spritz on a bottle). Thanks again for your time, regards, Steve On 13 June 2013 17:31, Julian Johnson <[email protected]> wrote: > On 13/06/2013 06:13, Steve Pratt wrote: > > Hi Guys, > thanks for this great tool Julian, and thanks to Olivier for the sample > scene that helped me get my head around it. > > As always, I had a play around and thought I had it completely sussed. > Now a job has turned up and I can't quite get it to work with instances. > Whenver I add instance geometry the instances interpenetrate. > I've tried using the Instance Geometry node and plugging it into the Add > Point node and tried the Instance shape node plugged into the Init Particle > Data node, but with no success. > Not sure what I'm doing wrong. > > Hi Steve, > > Dart Throw only works correctly with a spherical shape, sadly. It has no > concept of the size of the instances on the particle it just assumes > they're spheres governed by the particle size. I've been working on a > couple of things recently in order to upgrade Dart Throw: the ability to > input a specific array of sizes so that only those sizes would be used and > a small script to add an ICE attribute to each instance group member > specifying a correctly evaluated minimum sphere that would 'wrap' the > instance geometry (which could be fed into Dart Throw's size array). > Unfortunately, even a good minimum sphere (c.f. the very approximate min > spheres in the SDK) can leave huge volumes of the sphere unoccupied > (typically with a long thin instance) so the 'packing' can look pretty poor. > > With instances I'd recommend that you use a relaxation simulation > technique and actual shape RBDs i.e. spread your instances loosely around > the object you're trying to pack them onto and then apply forces to them to > 'push' them onto the surface, each frame using the post sim region to stick > the particle back to the closest location on the surface. With low > elasticity and bounce, eventually, the instances will settle onto the > surface and the native collision routines in the RBD simulation will take > care of interpenetration. Once you're happy with the distribution freeze > off the ICE tree. > > Julian > -- *"Twenty years from now you will be more disappointed with the things that you didn't do than by the ones you did do. So throw off the bowlines. Sail away from the safe harbour. Catch the trade winds in your sails. Explore. Dream. Discover."* - Mark Twain
