Circle Hit Detection

float radius =40;

float circle_X = 104;

float circle_Y = 60;

void setup() {

  size(400, 400);

}

​

void draw() {

  background(0, 50, 20);

  //is the mouse inside the circle?

  if ( dist(mouseX, mouseY, circle_X, circle_Y) < radius) { 

    fill(255, 0, 126);

    rect(300, 300, 100, 100);

  } else {

    fill(255);

    arc(200, 100, 40, 40, 0, PI+2);

  }

  ellipse(circle_X, circle_Y, radius*2, radius*2); 

  //drawing the circle is optional 

}