Blob tracking and collision detection

Processing Libraries
16

not sure but i would expect something like

void display(){
    float x = (maxx - minx)* 0.5 + minx;
    float y = (maxy - miny)* 0.5 + miny;
    fill(0,255,0);
    if ( checkCollision() ) fill(255,0,0);
    ellipse(x,y,(maxx-minx) + 30, (maxy-miny) + 30);
 }

//void noCollision(){
//  fill(0,255,0);
// }
  
//void isColliding(){
//  fill(255,0,0);
//}


boolean checkCollision() {
//...

that toggles the color for each drawn circle