I've been working with growth solvers using nearpoints() with some initial setups demonstrated by the brilliant folks at Entagma. However I'm getting a little stumped when I try to weight the growth in a certain direction. In other words, I'd like like the solver to find nearest points only in the +x direction of the currently infected points. Pointers? Ideas? Thanks!

Solver code:

float radius = 0.075;
int nbrs = nearpoints(0, “infected”, @P, radius);

int cnt = 0;
float accum = 0;

foreach(int nbr; nbrs){
float infection = point(0, “infect”, nbr);

float dist = length(@P - point(0, “P”, nbr));
float weight = 1 - smooth(0, radius, dist);
accum += infection * @Cd.r;


vector nodepos = point(0, “P”, nbr);
v@dir = normalize(nodepos - @P);

cnt++;
}

f@infect = f@infect + accum/float(cnt);

Ok so put another way, I need to find the vector between the current point and it's neighbor, and weight the ‘infect’ attribute in a certain direction. I've enclosing a simplified infection solver set up with a more compact algorithm

if u use the dot product between two vectors you get a scalar value that tells you how much the vector differ in their direction

Thanks, that's the ticket. My implementation isn't the greatest at the moment but it does seem to work, here's an example file