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Posts Tagged ‘actionscript’

Drawing A Sine Wave In Actionscript

August 7th, 2009 Adam 10 comments

Just a simple way to draw a sine wave with a specific amplitude and frequency. Use the sliders to adjust the values.
(Either JavaScript is not active or you are using an old version of Adobe Flash Player. Please install the newest Flash Player.)

Here’s the main function:

function drawWave(amp:int, freq:int):void{
	newSine.graphics.clear();
	newSine.graphics.lineStyle(2, 0xff0000, 0.4);
	newSine.graphics.moveTo(0, yaxis);
	for(var i:int=0; i<=stage.stageWidth; i++){
		var ang:Number = 2 * Math.PI * freq * i/stage.stageWidth;
		newSine.graphics.lineTo(i, yaxis - amp*Math.sin(ang));
	}
}

(EDIT 8/14/09: In the SWF above, the sine wave is upside down. That’s because I had a typo when I wrote it. On line 7 of the code, I had typed “…yaxis + amp…” but it should be minus. The code above is correct, but the SWF hasn’t been updated)

Categories: actionscript, flash Tags: , , , , , , ,

Draw A Quick Stage Border in Flash

July 9th, 2009 Adam 1 comment

Here’s a quick way to automatically add a border to your flash stage without drawing an actual object and resizing it. I use this snippet alot.

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var stagebox:Sprite = new Sprite();
stagebox.graphics.lineStyle(1, 0x000000, 1);
stagebox.graphics.drawRect(0, 0, stage.stageWidth-1, stage.stageHeight-1);
addChild(stagebox);
Categories: actionscript, flash Tags: , , , , ,

Random Motion in Flash

July 9th, 2009 Adam No comments

Here are two different methods of moving objects in random patterns, making them seem to wander around.

(Either JavaScript is not active or you are using an old version of Adobe Flash Player. Please install the newest Flash Player.)  (Either JavaScript is not active or you are using an old version of Adobe Flash Player. Please install the newest Flash Player.)

The one on the left is based on a brownian movement tutorial that uses variable velocities. The one on the right is based on a post about random circular movement. The latter is much more interesting, as the dot will rotate around an imaginary circle, and then after a random interval, the circle radius will change, and the dot will start on a new path around the new adjacent imaginary circle.

I think both methods are great, it just depends on what you want to use.

Here’s the code for the left method (brownian):

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// settings
var numDots:uint = 20;
var defaultDotSize:uint = 5;
var maxSpeed:Number = 0.5;
var dampen:Number = 0.95;
 
// make dots
function makeDots():void {
    // create desired number of dots
    for (var dotNum:uint=0; dotNum<numDots; dotNum++){
        var c1:Number = randomColor();
        var c2:Number = randomColor();
 
        // create dot
        var thisDot:MovieClip = new MovieClip();
        thisDot.graphics.beginFill(c1, .9);
        thisDot.graphics.lineStyle(defaultDotSize/3, c2, .9);
        thisDot.graphics.drawCircle(defaultDotSize, defaultDotSize, defaultDotSize);
        thisDot.graphics.endFill();
	thisDot.alpha = 0.5;
        addChild(thisDot);
 
        // coordinates
        thisDot.x = Math.random() * stage.stageWidth;
        thisDot.y = Math.random() * stage.stageHeight;
 
		// initial velocity
        thisDot.vx = 0;
        thisDot.vy = 0;
 
        // dot animation
        thisDot.addEventListener(Event.ENTER_FRAME, animateDot);
    }
}
makeDots();
 
// animation function
function animateDot(e:Event):void{
    var thisDot:Object = e.target;
 
    // apply randomness to velocity
    thisDot.vx += dampen*(Math.random() * maxSpeed - maxSpeed/2);
    thisDot.vy += dampen*(Math.random() * maxSpeed - maxSpeed/2);
 
   	// keep dot inside stage
    if(thisDot.x+thisDot.width >= stage.stageWidth)
		thisDot.vx = -maxSpeed;
    else if(thisDot.x <= 0)
		thisDot.vx = maxSpeed;
    else if(thisDot.y+thisDot.height >= stage.stageHeight)
		thisDot.vy = -maxSpeed;
    else if(thisDot.y <= 0)
		thisDot.vy = maxSpeed;
 
	// apply velocity
    thisDot.x += thisDot.vx;
    thisDot.y += thisDot.vy;
}
 
function randomColor():Number{
    return Math.floor(Math.random() * 16777215);
}

Here’s the code for the right method (circular):

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// settings
var numDots:int = 20;
var defaultDotSize:uint = 5;
var step:int = 1;
var maxRadius:int = 50;
var minRadius:int = 5;
var minInterval:int = 400;
var maxInterval:int = 1200;
 
function makeDots():void {
    // create desired number of dots
    for (var dotNum:uint=0; dotNum<numDots; dotNum++){
        var c1:Number = randomColor();
        var c2:Number = randomColor();
 
        // create dot
        var thisDot:MovieClip = new MovieClip();
        thisDot.graphics.beginFill(c1, .9);
        thisDot.graphics.lineStyle(defaultDotSize/3, c2, .9);
        thisDot.graphics.drawCircle(defaultDotSize, defaultDotSize, defaultDotSize);
        thisDot.graphics.endFill();
	thisDot.alpha = 0.5;
        addChild(thisDot);
 
        // dot properties
		thisDot.radius = Math.random() * (maxRadius - minRadius) + minRadius;
		thisDot.centerX = Math.random() * (stage.stageWidth - thisDot.radius*2 - thisDot.width*2) + thisDot.radius + thisDot.width;
		thisDot.centerY = Math.random() * (stage.stageHeight - thisDot.radius*2 - thisDot.height*2) + thisDot.radius + thisDot.height;
		thisDot.rotationIncrement = (dotNum%2==0?1:-1) * 360 / (2*Math.PI*thisDot.radius/step);
		thisDot.currentRotation = thisDot.rotationIncrement;
		var radians:Number = Math.PI/180*thisDot.currentRotation;
		var vy = Math.sin(radians);
		var vx = Math.cos(radians);
		thisDot.y = thisDot.centerY + vy*thisDot.radius;
		thisDot.x = thisDot.centerX + vx*thisDot.radius;
		thisDot.intrvl = setInterval(swapInterval, Math.random()*(maxInterval-minInterval)+minInterval, thisDot);
 
        // dot animation
        thisDot.addEventListener(Event.ENTER_FRAME, animateDot);
    }
}
makeDots();
 
// animation function
function animateDot(e:Event):void{
	var thisDot:Object = e.target;
 
	thisDot.currentRotation += thisDot.rotationIncrement;
	var radians:Number = Math.PI/180*thisDot.currentRotation;
	var vy = Math.sin(radians);
	var vx = Math.cos(radians);
 
	thisDot.y = thisDot.centerY + vy*thisDot.radius;
	thisDot.x = thisDot.centerX + vx*thisDot.radius;
 
	// keep dot inside stage
	if(thisDot.x + thisDot.width > stage.stageWidth || thisDot.x < 0 || thisDot.y + thisDot.height > stage.stageHeight || thisDot.y < 0)
		thisDot.rotationIncrement *= -1;
}
 
// creates new point to rotate around
function swap(thisDot:Object):void{
	// pick a new random length for the radius
	var newRadius:Number = Math.random()*(maxRadius-minRadius)+minRadius;
 
	// determine new center based on old center, dot's current position and new radius
	var xd:Number = thisDot.centerX-thisDot.x;
	var yd:Number = thisDot.centerY-thisDot.y;
	var ratio:Number = (thisDot.radius+newRadius)/thisDot.radius;
	thisDot.centerX = thisDot.centerX-xd*ratio;
	thisDot.centerY = thisDot.centerY-yd*ratio;
	thisDot.radius = newRadius;
 
	// rotate the opposite direction around new point
	var dir:int = thisDot.rotationIncrement>0 ? 1 : -1;
	thisDot.rotationIncrement = dir* -1 * 360 / (2*Math.PI*thisDot.radius/step);
	thisDot.currentRotation -= 180;
}
 
// random interval to change the point of rotation
function swapInterval(thisDot:Object){
	clearInterval(thisDot.intrvl);
	thisDot.intrvl = setInterval(swapInterval, Math.random()*(maxInterval-minInterval)+minInterval, thisDot);
	swap(thisDot);
}
 
function randomColor():Number{
    return Math.floor(Math.random() * 16777215);
}
Categories: actionscript, flash Tags: , , , , ,