connection_nodes.pde

// TODOs
// - boolean for node overlay
// -- if overlay redraw node

Node[] node = new Node[25];

void setup() {
  size(400, 400);
  background(255);
  smooth();
  
  noStroke();
  
  // Display nodes
  for ( int i = 0; i < node.length; i++ ) {
    float r = random(10, 50);
    float x = random(r, width - r);
    float y = random(r, height -r);
    node[i] = new Node(x, y, r);
    node[i].display();
  }
  
  // Connect nodes
  for ( int i = 0; i < node.length; i++ ) {
    stroke(50, 187, 237, 25);
    for ( int j = 0; j < node.length; j++ ) {
      if ( i != j ) {
        line(node[i].x, node[i].y, node[j].x, node[j].y);
      }
    }
  }
  
}

Node.pde

class Node {
  float x, y, r;
  
  Node( float temp_x, float temp_y, float temp_r ) {
    x = temp_x;
    y = temp_y;
    r = temp_r;
  }
  
  void display() {
    noStroke();
    fill(50, 187, 237, 75);
    ellipse(x, y, r+10, r+10);
    fill(50, 187, 237);
    ellipse(x, y, r, r);
  }
}