+void
+object_init (Object *object, double x, double y, double mass)
+{
+ object->position.x = x;
+ object->position.y = y;
+ object->previous_position.x = x;
+ object->previous_position.y = y;
+ object->mass = mass;
+}
+
+void
+spring_init (Spring *spring, Object *a, Object *b, double length)
+{
+ spring->a = a;
+ spring->b = b;
+ spring->length = length;
+}
+
+void
+offset_spring_init (OffsetSpring *spring, Object *a, Object *b,
+ double dx, double dy)
+{
+ spring->a = a;
+ spring->b = b;
+ spring->dx = dx;
+ spring->dy = dy;
+}
+