The attraction, repulsion, and spinning forces

Let's extend our particle's model with three new control parameters—attraction/repulsion, spinning forces inside the emitter (the force and spinning parameters), and friction that freezes the motion (the friction parameter).

Note

An example of this is 03-Particles/03-ParticlesForces.

The example is based on the 03-Particles/02-ParticlesEmitter project, implemented in the previous section. Add a declaration of the new parameters to the Params class declaration:

float force;       //Attraction/repulsion force inside emitter
float spinning;    //Spinning force inside emitter
float friction;    //Friction, in the range [0, 1]

Then add their initialization in Params::setup():

force = 0;
spinning = 0;
friction = 0;

Finally, implement these parameters by inserting the following code in the Particle::update() function after the vel.rotate(...) line:

ofPoint acc;         //Acceleration
ofPoint delta = pos - param.eCenter;
float len = delta.length();
if ( ofInRange...