var ball:MovieClip = _root.attachMovie("ball", "ball", 2, {_x:250, _y:100}); var elastic:MovieClip = _root.createEmptyMovieClip("elastic", 1); var point1:MovieClip = _root.attachMovie("sling", "point1", 3, {_x:50, _y:200}); var point2:MovieClip = _root.attachMovie("sling", "point2", 4, {_x:450, _y:200}); var gravity = 0.1; var angle1:Number = 0; var angle2:Number = 0; var radius:Number = 13.0; // Or whatever half the width of your ball is. var elasticCoefficient:Number = 0.001; // This number will affect the stretchiness of the sling. The greater the number // the tighter the elastic will be. var released:Boolean = true; var forced:Boolean = false; var acc:Object = {x:0, y:0}; var vel:Object = {x:0, y:0}; _root.onMouseDown = function() { ball._x = _root._xmouse; ball._y = _root._ymouse; ball.startDrag(); _root.released = false; vel.x = 0; vel.y = 0; }; _root.onMouseUp = function() { ball.stopDrag(); _root.released = true; }; ball.onPress = function() { ball.startDrag(); _root.released = false; vel.x = 0; vel.y = 0; }; ball.onRelease = function() { ball.stopDrag(); _root.released = true; }; _root.onEnterFrame = function() { elastic.clear(); elastic.lineStyle(3, 0xFF0000); if (released) { ball._x += vel.x; ball._y += vel.y; } if (ball._y>=187) { /* This area differs from the code in the tutorial. The reason for that is I didn’t read the code, I just looked at the examples. I try to gain experience with problem-solving by doing things as close to by myself as possible. */ forced = true; var x1:Number = ball._x-point1._x; var y1:Number = ball._y-point1._y; var x2:Number = point2._x-ball._x; var y2:Number = point2._y-ball._y; var distance1:Number = Math.sqrt(x1*x1+y1*y1); var distance2:Number = Math.sqrt(x2*x2+y2*y2); _root.angle1 = Math.atan2(y1, x1); _root.angle2 = Math.atan2(y2, x2); var xOffset:Number = Math.cos(angle1+Math.PI/2)*radius; var yOffset:Number = Math.sin(angle1+Math.PI/2)*radius; var xOffset2:Number = Math.cos(angle2+Math.PI/2)*radius; var yOffset2:Number = Math.sin(angle2+Math.PI/2)*radius; angle1 += Math.sin(radius/distance1); angle2 += Math.sin(radius/distance2)*-1; elastic.moveTo(point1._x, point1._y); elastic.lineTo(ball._x+xOffset, ball._y+yOffset); elastic.moveTo(point2._x, point2._y); elastic.lineTo(ball._x+xOffset2, ball._y+yOffset2); } else { forced = false; elastic.moveTo(point1._x, point1._y); elastic.lineTo(point2._x, point2._y); } acc.x = 0; acc.y = 0; acc.y = gravity; if (released && forced) { /* This section applies the force of the sling to the ball in terms of acceleration based on the stretching of the sling, in the direction of the displacement, scaled by a coefficient that also encapsulates the mass of the ball. */ acc.x += distance1*Math.sin(angle2)*elasticCoefficient; acc.y += -distance1*Math.cos(angle1)*elasticCoefficient; acc.x += distance2*Math.sin(angle1)*elasticCoefficient; acc.y += -distance2*Math.cos(angle2)*elasticCoefficient; } if (released) { vel.x += acc.x; vel.y += acc.y; } };