You have two problems. One, how to calculate a spiral path along a cone, and two, learning steering/flocking algorithms. The first is to simply write a function f(x,y,z) that behaves like an Archimedes spiral or some such. See Wikipedia for the math behind different spirals. Then, the right algorithm would allow you to move particles along the path. See http://www.red3d.com/cwr/boids/ as an example for the flocking of birds.

Of course, one should mention that tornadoes do not follow a single 3D spiral…

hi there,

i m trying to move particles in a conical spiral path from top to bottom which some thing looks like a tornado… in c++

so kindly help me in with a solution

cheers,

emphy