Hi, I am developing a simulation of flocking for my thesis.
I am using Unity3D and C#.
For fast calculation of K-nearest neighbors I use the alglib library, which provides methods for it (uses a K-D tree). It also supports approximate knn for faster results, which is what I'm using since I don't need 100% accuracy.
In my tests I have 500 boids (birds) flying around. They are spawned near to each other so they form a swarm. However, after some seconds, this big swarm begins to break into smaller ones. I'm 99% certain that this is because for Cohesion's a-knn I use 30 for k, which means take into account the 30 "closest" (not really the 30 closest since I'm using aknn).
This has the effect that I described above - many small swarms of about 30 boids each, which is very logical since each boid considers a neighborhood of 30 closest boids for Cohesion).
When I change the k for Cohesion to bigger numbers (e.g 100) less swarms are formed. If I set k to 500 only one is formed. But this has a very big downside.
For k = 30, I get ~20 fps
For k = 500, I get ~3 fps
[a-knn epsilon is 50.0 for both)
Is there a solution to this? I'd like less swarms but better performance.
Is alglib slow? I couldn't find something else... I'm not doing anything special in my code, just the usual behaviors - Cohesion, Separation and Velocity Match. And one more, Cohesion to an anchor object so the flock will follow a path I want.
Thanks in advance.
Edited by sheep19, 05 April 2014 - 08:21 AM.