public void Swap(int[] bodies, int islandCount)
{
//Pick a body. Find all bodies of its type.
//Put them all in the same spot, starting at the body with the lowest index.
if (bodyIndex >= bodies.Length)
{
bodyIndex = 0;
}
var bodyType = bodies[bodyIndex];
int lowestIndex = -1;
QuickList <int, Array <int> > .Create(pool, 128, out var islandBodyIndices);
for (int i = bodies.Length - 1; i >= 0; --i)
{
if (bodies[i] == bodyType)
{
lowestIndex = i;
islandBodyIndices.Add(i, pool);
}
}
var baseIndex = Math.Min(bodies.Length - islandBodyIndices.Count, lowestIndex);
Array.Sort(islandBodyIndices.Span.Memory, 0, islandBodyIndices.Count);
for (int i = 0; i < islandBodyIndices.Count; ++i)
{
IslandCacheConvergence.Swap(ref bodies[baseIndex + i], ref bodies[islandBodyIndices[i]]);
}
bodyIndex += islandBodyIndices.Count;
islandBodyIndices.Dispose(pool);
}
public void Swap(int[] bodies, int islandCount)
{
//Pick a body. Does it have any connections that are currently positioned to the right?
//This will pointlessly shuffle all island neighbors to the right.
//The goal here is just super simplicity.
//(This is roughly equivalent to checking a body's connections, seeing if any are to the right, and if they are, pulling them to be a neighbor.
//This is NOT a globally stable heuristic- even after it 'converges' it will continually reshuffle the elements within islands.
//If you had full island information, you could grab only one and stick it onto the end of the currently gathered island set....)
var nextIndex = (swapIndex + 1) % bodies.Length;
for (int i = (nextIndex + 1) % bodies.Length; i < bodies.Length; ++i)
{
if (bodies[i] == bodies[swapIndex])
{
IslandCacheConvergence.Swap(ref bodies[i], ref bodies[nextIndex]);
//Just do one.
break;
}
}
swapIndex = nextIndex;
}
