Particles and if/else statements

I am creating an interaction and I need to say “if all 8 particles are inside this circle, then change the opacity of the circle from 0 to 100.”

My code is here:
Image ref attached! I’ve got the circle’s opacity holding at 50% right now, just as a placeholder

What problem(s) are you running into right now, specifically?

I’m a super beginner and I just don’t know what syntax to use, to write this if/else concept, and then where to put it. I’m assuming it put it in the draw function, and maybe a separate if/else statement of each circle?

A bit more info:
In my draw function is the code pasted below. I have 7 circles total, but i’ve pasted the code for one of them below. I have a variable ‘opacityPressed’ that I can use in the if/else statement.

//---------------draw the circle and outer ring of circle----------------------
    ofSetColor(243,167,153); //pink

//---------------springs and particles----------------
for (int i = 0; i < particles.size(); i++){

for (int i = 0; i < springs.size(); i++){

//this is where I think I should put the if/else.

you need a variable to represent the circle’s position (say an ofPoint called circlePos) and its radius (say float radius…), then you could do:

bool bAnyNotInMe = false;
for (int i = 0; i < particles.size(); i++){
     if (  (circlePos - particles[i].pos).length() > radius){
           bAnyNotInMe = true;

if (bAnyNotInMe == false){  // ok all particles are inside: 
      // do something
} else {
     // do something else

this is just for one circle, but you can get the idea… we are trying to see if any particles are not in the circle, and that gives us a true / false if all are in the circle.