// The Nature of Code
// Daniel Shiffman
// http://natureofcode.com

// Mover object
Bob bob;

// Spring object
Spring spring;

void setup() {
 size(640,360);
 // Create objects at starting position
 // Note third argument in Spring constructor is "rest length"
 spring = new Spring(width/2,10,100); 
 bob = new Bob(width/2,100); 

}

void draw() {
 background(255); 
 // Apply a gravity force to the bob
 PVector gravity = new PVector(0,2);
 bob.applyForce(gravity);
 
 // Connect the bob to the spring (this calculates the force)
 spring.connect(bob);
 // Constrain spring distance between min and max
 spring.constrainLength(bob,30,200);
 
 // Update bob
 bob.update();
 // If it's being dragged
 bob.drag(mouseX,mouseY);
 
 // Draw everything
 spring.displayLine(bob); // Draw a line between spring and bob
 bob.display(); 
 spring.display(); 
 
 fill(0);
 text("click on bob to drag",10,height-5);
}


// For mouse interaction with bob

void mousePressed() {
 bob.clicked(mouseX,mouseY);
}

void mouseReleased() {
 bob.stopDragging(); 
}