Just a simple way to draw a sine wave with a specific amplitude and frequency. Use the sliders to adjust the values.
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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)
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); |
Here are two different methods of moving objects in random patterns, making them seem to wander around.
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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);
} |