I am experimenting with boid particles and I have set up an ant fight simulation, where there are two enemy boid systems emitted from different areas (vertex groups) of a plane. "Allow Land" is enabled, "Allow Flight" is disabled (i.e., they crawl but do not fly).

Their "boid brain" rules include "Fight" and indeed they do go after one another. Unfortunately I've had difficulty finding information about how the system uses the combat data. It sort of looks like some of the particles slow down and perhaps stop after combat (maybe if their health is low?) and occasionally some seem to just disappear (maybe if their health goes to zero? does a critically wounded boid just keep losing health even if it is not attacked, or does a dead boid just stick around for a while before disappearing?).

So part of my question is just trying to determine what the default programmed behavior is, if this is documented somewhere it would be handy. But I'm also interested in finding out whether I can change or supplement this behavior. Could I access the particle health status in a driver (perhaps to drive a shape key) or via the Attribute node? Is there an attribute that tells me whether a particle is engaged in combat?

If that's too vague: ideally I would like my ants to go into a fighting pose when they are fighting (maybe rearing up on their back legs?) and when dead maybe turn upside down or change color or something. This is both to simply understand what's happening (how savage the battle is) and ultimately to depict the combat animation with a bit of realism. Thanks in advance!


1 Answer 1


I think you are expecting too much from the boids fight option. The boids documentation describes fight as Move toward nearby boids. It won't animate two ants in combat for you.

For more advanced simulation options have a look at Crowd Master or the commercial Crowd Sim 3D.

  • $\begingroup$ I guess I'm not "expecting" anything at all, rather I'm trying to understand what's provided, including the limitations thereof. I have found boids to be poorly documented even by blender standards, and while I love blender we all know its documentation is sometimes sparse, that's exactly why this site is so valuable. I appreciate the links, my goal is more to "understand boids" than to find other solutions. $\endgroup$
    – risingfall
    Jun 8, 2019 at 12:19

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