Oops, I'm culling to many boxes now, I should have double checked it before uploading. If someone for some strange reason wants to use this, change the expression component that contains the following formula: "sqrt(6)*x" to "sqrt(3)*x*2"
On Dec 4, 9:51 am, visose <[EMAIL PROTECTED]> wrote: > I added a culling component that should drastically speed things up. > Still slow though.http://grasshopper3d.googlegroups.com/web/marchingcubes2.ghx > > On Dec 4, 12:38 am, visose <[EMAIL PROTECTED]> wrote: > > > I managed to create a definition that emulates the marching cube > > process. > > I'd thank David for the pointer, but by the time he comes back this > > thread will be deeply buried (hopefully). > > I tried to do it completely out of gh components, but I ended up > > inevitably with a scripting component (but with very little code). > > Note that it's very inefficient to do this sort of thing using only > > components so it's really slow. > > It should be able to recreate any type isosurface. > > The method i used is very simple but very limited, for example: > > there's no smooth shading of the mesh and there are some special cases > > that are not checked for (not to mention the speed). > > Example image (low > > detail):http://grasshopper3d.googlegroups.com/web/marchingcubes.jpg > > Definition:http://grasshopper3d.googlegroups.com/web/marchingcubes.ghx > > > If someone has any idea how to make it faster (besides scripting it > > completely) please tell. > > > On Dec 2, 3:36 pm, David Rutten <[EMAIL PROTECTED]> wrote: > > > > No, I don't think Delaunay is a good approach for this. This shape > > > requires a true 3D algorithm. Actually, the shape looks like it might > > > be the result of a Marching Cube process, and as always, it's usually > > > much easier to find good algorithms for very strict shapes than for > > > generic ones. With such a high degree of symmetry, I suppose a custom > > > solution would give you a better result that you could possibly > > > achieve otherwise. > > > > -- > > > David Rutten > > > Robert McNeel & Associates > > > > On Dec 2, 4:23 pm, visose <[EMAIL PROTECTED]> wrote: > > > > > What would be the best approach to create the skin for this > > > > shape?:http://grasshopper3d.googlegroups.com/web/schwartz2.jpg > > > > Discussed in this > > > > thread:http://groups.google.com/group/grasshopper3d/browse_thread/thread/fde... > > > > This skin in the screenshot is done by creating panels over several > > > > point grids (and culling the unwanted panels). You can't create this > > > > object by a continuous surface (i think). The problem is that with > > > > this method some panels overlap. The superposed point grids create an > > > > unordered point cloud that could be triangulated. > > > > > I was thinking that maybe if the delaunay triangulation had a distance > > > > threshold, and the points where close enough on the imaginary surface, > > > > it would only triangulate on the right spots and wouldn't create > > > > triangulations all over the place (well, maybe on edges but the > > > > curvature is continuous in this example). In this case, i don't think > > > > there's a useful guide geometry. > > > > > On Dec 2, 2:47 pm, David Rutten <[EMAIL PROTECTED]> wrote: > > > > > > Delaunay is pretty easy, but it's a 2D algorithm so there's always > > > > > some extra stuff that needs doing when using it in a 3D environment. > > > > > This is why the PoistSetReconstruction plugin uses Guide geometry, to > > > > > convert a 3D point cloud into a 2.5D point cloud. > > > > > > Once Delaunay is finished, it's quite easy to bolt a 2D voronoi cell > > > > > solver on top. 3D voronoi is much harder to do efficiently. It's not > > > > > as easy to discard certain points, which means you end up doing a lot > > > > > of unnecessary solid boolean operations slowing the whole thing > > > > > down... > > > > > > -- > > > > > David Rutten > > > > > Robert McNeel & Associates > > > > > > On Dec 2, 2:29 pm, visose <[EMAIL PROTECTED]> wrote: > > > > > > > Very nice. I also used voronoi a couple years ago as one of the > > > > > > parameters of urban planning for a school project. The realtime > > > > > > manipulation of grasshopper would've come really handy. Is the > > > > > > delaunay algorithm much harder to implement? I'd like to use it to > > > > > > mesh some unordered point clouds. > > > > > > > On Dec 2, 8:29 am, Dimitrie <[EMAIL PROTECTED]> wrote: > > > > > > > > hello oompa, > > > > > > > as i was also needing some sort of space-partitioning algorithm > > > > > > > for an > > > > > > > urbanism project tomorrow, i tried and managed to pull up a > > > > > > > grasshopper voronoi node, based on david's algorithm > > > > > > > you can check it out > > > > > > > herehttp://dimitrie.wordpress.com/2008/12/01/grasshopper-voronoi-diagram/ > > > > > > > > On Nov 25, 7:44 pm, oompa_l <[EMAIL PROTECTED]> wrote: > > > > > > > > > is this possible with grasshopper yet? maybe it always has > > > > > > > > been...if > > > > > > > > anyone has any clues on this, I could use it right now... > > > > > > > > > thanks!
