Introducing "wander" to particle movement

[stefan-albertz]

Craig Reynolds came up with the wander movement in his boid-systems... how to do it with particles?

I´ve a firework shot to do and i thought that i could use that wander behaviour to make the flight-path a bit more natural (without using a field). imagine a rocket that explodes, split into 10 parts, each part flying away (inherited velocity + own initial thrust) and while flying, starting to leave the path, like spinning a bit of. Those fireworks look a bit like flyes. Like as if they inherit a life of their own when they are released from the main rocket.

I tried to find a way to use noise to manipulate the velocity vector, but my math knowledge has some flaws here. If i construct a vector vertical to the velocity vector and add it to it to create a new velocity then appliying the stored length of the original vel-vector back onto the new one the problem would be solved. The problem is: setting up the vector vertically onto the original vel-vector. Since there is the "circular freedom" around the vector, there are too many unknown variables to solve the solution .. Reynolds solved it - his flock-of-birds to 3d movements that "slowly" change their direction in 3d space .. i "only" need that code part ...

any help on that would be appreciated!!

Stefan

[joojaa]

Add a turbulence field

[stefan-albertz]

Turbulence is not what i would like to use here since the turbulence would introduce force in a too random fashion. The particles should look like having an engine on their own - i tried turbulence and it simply didn´t make it.

[joojaa]

Ahh ok. You could offset thet with a drag field that would kill the particle acceleration caused by it tough..

But yes you can simply just a add a pre/post dynamics script that slightly turns the velocity each frame (you can store it if you wish the turn to stay persistent for longer than a frame). This would keep the momentum you have right now. Is that a good solution for you? It would look something like this:

$magnitude=0.5; //use some attribute so you can change it easily
$frequency=frame*0.5; //same Here
$speed=mag(particleShape1.velocity);
$nuDir=particleShape1.velocity+$magnitude*noise
<<particleShape1.particleId*12+$frequency,
  particleShape1.particleId*22+$frequency,
  particleShape1.particleId*44+$frequency>>
);
particleShape1.velocity=unit($nuDir)*$speed;

But the possibilities are limitless. Just your math skill is the limit really, makes the calculus teacher say i told you so.

Another way would be to preplot all the movement with a randomized curve function taht way each one of the would have thir own purpose in the game. It allows you tohave pretty accurate controll over each particle, its used in one of my older tests taht still happens to be on line to watch.

quicktime movie

Obviously the result can be more random than that. But theese particles definitely have a plan at their hand.

[deepak-dhawan]

@Joojaa: _Another way would be to preplot all the movement with a randomized curve function taht way each one of the would have thir own purpose in the game. It allows you tohave pretty accurate controll over each particle, its used in one of my older tests taht still happens to be on line to watch.

quicktime movie

Obviously the result can be more random than that. But theese particles definitely have a plan at their hand.

---

the movie had some cool particle movement..could you share the file.... i want the result like that in 1 of my project.

thanks in advance

[joojaa]

Im afraid the file is  gone into digital heaven. Its would be easy enough to remake tough.

the movement is just based on a hermite curve that has  2 goal meshes and their tangents into the hermite functions points and each particle is driving along this spline with a custom attribute + time for a randomized start time.