// variable stating if I clicked the mouse
clicked = false;
// variable stating if I am dragging the mouse
dragging = false;
// flag determining if an unit was selected
unit_selected = false;
// 10 times loop
for (x=1; x<=10; x++) {
	// can_place = true: I can place the unit / false: I can't
	// initializing it to false to force entering the while loop
	can_place = false;
	// while loop to look for an empty space where to place the unit
	while (!can_place) {
		// setting can_place to true
		// you can always place an unit until you can't...
		can_place = true;
		// generating random x and y positions, and random width
		px = Math.floor(Math.random()*400)+50;
		py = Math.floor(Math.random()*300)+50;
		w = Math.floor(Math.random()*20)+30;
		// scanning all already placed units
		for (y=x-1; y>=1; y--) {
			// determining the distance between the y-th unit and the one I am trying to place
			dist_x = px-_root["sphere_"+y]._x;
			dist_y = py-_root["sphere_"+y]._y;
			distance = Math.ceil(Math.sqrt(dist_x*dist_x+dist_y*dist_y));
			// this is the minimum distance I want between two units:
			// the sum of both radiuses plus 20 pixels
			min_distance = (w+_root["sphere_"+y]._width)/2+20;
			// if the new unit would be too close to an existing one...
			if (distance<min_distance) {
				// set can_place to false
				can_place = false;
			}
		}
	}
	// I exited the while loop so I can place the unit...
	// ... let's do it...
	nano = _root.attachMovie("sphere", "sphere_"+x, x, {_x:px, _y:py, _width:w, _height:w});
	// function to be executed at every frame for every unit
	nano.onEnterFrame = function() {
		// if I am dragging...
		if (dragging) {
			// if the center of the unit is inside the square I made dragging the mouse...
			if ((this._x>Math.min(click_x, posx)) and (this._x<Math.max(click_x, posx)) and (this._y>Math.min(click_y, posy)) and (this._y<Math.max(click_y, posy))) {
				// ... mark the unit as selected
				this.gotoAndStop(2);
			}
			else {
				// else mark the unit as unselected
				this.gotoAndStop(1);
			}
		}
		else {
			// if there is at least one unit selected...
			if (unit_selected) {
				// if the mouse is over this unit and this is an unselected unit...
				if (this.hitTest(_root._xmouse, _root._ymouse, true) and this._currentframe == 1) {
					// mark the unit as destination unit
					this.gotoAndStop(3);
				}
				// if the mouse is not over this unit and this unit is marked as destination unit... 
				if (!this.hitTest(_root._xmouse, _root._ymouse, true) and this._currentframe == 3) {
					// mark the unit as unselected unit
					this.gotoAndStop(1);
				}
			}
		}
	};
	// start with unselected unit
	nano.gotoAndStop(1);
}
// creation of a movieclip where I will draw the square made by mouse dragging
_root.createEmptyMovieClip("selmovie",_root.getNextHighestDepth());
// creation of a movieclip where I will draw lines from units
_root.createEmptyMovieClip("unitlines",_root.getNextHighestDepth());
// function to be executed every time I press the mouse
_root.onMouseDown = function() {
	// saving mouse coordinates
	click_x = _root._xmouse;
	click_y = _root._ymouse;
	// I clicked
	clicked = true;
};
// function to be executed every time I move the mouse
_root.onMouseMove = function() {
	// if I clicked...
	if (clicked) {
		// I am dragging
		dragging = true;
		// saving acutal x and y mouse positions
		posx = _root._xmouse;
		posy = _root._ymouse;
		// clearing the movieclip I am about to draw on
		selmovie.clear();
		// setting the line style of the movieclip
		selmovie.lineStyle(2,0x000000,50);
		// setting the filling of the movieclip
		selmovie.beginFill(0xff0000,30);
		// drawing a square connecting the point I first clicked on and the point I am currently on
		selmovie.moveTo(click_x,click_y);
		selmovie.lineTo(posx,click_y);
		selmovie.lineTo(posx,posy);
		selmovie.lineTo(click_x,posy);
		selmovie.lineTo(click_x,click_y);
		// at this time the square is filled, and you can omit next line
		selmovie.endFill();
 
	}
};
// function to be executed every time I release the mouse
_root.onMouseUp = function() {
	// clearing the drag square
	selmovie.clear();
	// saving mouse position
	xmouse = _root._xmouse;
	ymouse = _root._ymouse;
	// if I am not dragging...
	if (!dragging) {
		// scanning for all units
		for (x=1; x<=10; x++) {
			// determining distance between the units and the mouse
			dist_x = _root["sphere_"+x]._x-xmouse;
			dist_y = _root["sphere_"+x]._y-ymouse;
			distance = Math.floor(Math.sqrt(dist_x*dist_x+dist_y*dist_y));
			// if the distance is less than unit's radius...
			if (distance<_root["sphere_"+x]._width/2) {
				// mark the unit as selected
				_root["sphere_"+x].gotoAndStop(2);
			}
			else {
				// else mark the unit as unselected
				_root["sphere_"+x].gotoAndStop(1);
			}
		}
	}
	// I am not clicking             
	clicked = false;
	// I am not dragging
	dragging = false;
};
_root.onEnterFrame = function() {
	// no units selected at the moment...
	unit_selected = false;
	// clearing the mc
	unitlines.clear();
	// if I am not dragging the mouse to select multiple units...
	if (!dragging) {
		// setting the line style
		unitlines.lineStyle(1,0x888888,100);
		// scanning through all units
		for (x=1; x<=10; x++) {
			// if the unit is selected
			if (_root["sphere_"+x]._currentframe == 2) {
				// drawing a line from the centre of the unit to mouse position
				unitlines.moveTo(_root["sphere_"+x]._x,_root["sphere_"+x]._y);
				unitlines.lineTo(_root._xmouse,_root._ymouse);
				// at least a unit was selected
				unit_selected = true;
			}
		}
	}
};