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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(x1x1y1*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 += distance1Math.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;
}
};