I have two vellum grain setups which I try to merge into one solver. On one side I have a box filled with grains. On the other side use the "vellum configure grain pieces" to generate a rigid body which falls into the grains. (Screenshot)
As soon as I tell the solver in the advanced tab "ignore neighbors with Same Name or Piece" the right grain stream (box filled with grains) has no more self collisions because it considers it as one piece. But if I turn this checkbox off, I get my self collisions back but my grain pieces explode because they are not longer recognized as pieces.
I can't figure out how to let the those rigid pieces drop into a grain tank only with vellum. I'm sure it works. I'm missing something here. Maybe the right hand grain stream needs a different piece attrib on every grain?
Ignore Neighbors with Same Name or Piece Ignore any neighbors that have the same non-empty name or non-negative piece point attribute. This option can be enabled to create separate clusters of grains that only interact with other clusters, often in conjunction with a Shape Match constraint to give rigid behavior.
so make sure that your particles from box either have empty s@name attribute or negative i@piece attribute after your merge and unpack
judging from your screenshot you are probably not using s@name to define pieces, as that would be empty after merge and unpack
but however you are creating the i@piece attribute you are using to define piece, make sure it's default value is -1, so that after merging with geometry that doesn't have such attrib defined it would be initialized to -1 and not 0
you can also look at John's grains_as_pieces_named.hip file from the presentation you attached, he is using s@name (and not i@piece) to define pieces, but follows the same logic described in help, so the s@name is empty for sand filling the pool
If anyone is also having this issue turn off assume uniform radius under grain collision in the Advanced tab. This will solve some "the number of points in the geometry and constraints do not match" errors.
