Posts Tagged ‘as3


AS3 Flamer Class :: Setting things on fire

The Flamer Class is a quick and easy method to set things on fire. Throw some fuel (any display object) at the class and make it burn.

While working on another project I needed to make some lightweight flames. I looked around, tried a bit of perlin noise, some convolution filters – then some PixelBender filtering – I wasn’t really happy with the results.

I found the excellent Saqoosha’s Fire on Wonderfl.
This demo had nearly the flicker and colour mapping that I was looking for. Rendering the perlin noise on each frame was causing a bit too much processor overhead for my purposes.
Instead of rendering two perlin octaves and moving the layers against each other, I took two separate single octave perlin noise bitmaps and rotated one against the other while blending.
This gives a nice effect and is very lightweight. With the Saqoosha method I was clocking at a steady 26fps, with my lightweight method I could get 90fps.

To get the flame hues I set up a gradient box, threw some colours at it, loaded those colours into an array which I then pushed to a palette map.

So how to use the Flamer class:

import swingpants.effect.Flamer

var flamer:Flamer=new Flamer(display_object)

addEventListener(Event.ENTER_FRAME, enterFrameHandler)
function enterFrameHandler(event:Event):void

Your object will now be on fire. Feel naughty?

You can set the render width and height and also set the direction of the flames by setting a point vector.

var flamer:Flamer=new Flamer(display_object,render_width, render_height, flame_direction_point)

//The colour of the flames can be set with one of the presets (There are 4 at the moment – ORANGE_FLAME, BLUE_FLAME, YELLOW_FLAME, GREEN_FLAME – but I will be adding more)

//Direction can be set on the fly:

Here is a demo of a pure code use of the Flamer: The Flaming Vortex. You can click on the flash to initiate an explosion, and pressing space will change the colour. Have a play:

Flaming Sun

Flamer Class. The flaming vortex demo

This next demo is an example of throwing a movieclip/sprite at the Flamer class. Don’t laugh, I quite literally spent 10 minutes putting the anims together then threw them at the Flamer. Click on Flash to change colour and object.

Flaming Car

Flamer Class Demo. Help, my car is on fire

Lots of fun can be had by throwing different animations at the Flamer. Control some with your mouse/keys. Become a twisted fire starter.

The Flamer class could do with a few more features, but is a pretty good start. The speed is pretty good, I’m happy to receive any improvement recommendations.

I have packed the Flamer class and demos up in a zip if you want to have a play:
DOWNLOAD: Flamer Class and Demos

DEMO #1: Flaming Vortex
DEMO #2: Burning Movieclips


Ranged Numbers. Non-Linear response curves for Sliders and TouchPads.

I’ve been building a few apps recently and have found that a linear response over a range of numbers has been a poor solution. I needed to be able to apply different response curves to user interface components (knobs, sliders, touchpads) as well as on screen display objects, characters, etc.

I needed a good name for the class, but instead came up with the pretty poor moniker ‘RangedNumbers’. I’ll change it when I come up with a better one.

So the idea is, a ‘ranged number’ is instantiated, initialised for the required range then a simple call with a value in that range will result with a percentage that can be applied to the intended recipient accordingly. I realised that an inverted curve would be handy too, so have added that functionality.

I have included exponential and powered curves as well as linear.

So to use the ranged number system:

//Instantiate and Initialise
var ranged_num:RangedNumber=new RangedNumber(min,max)
//Where min is the minumum number in the range and max is the maximum

//In use:
trace ( ranged_num.calculatedRangeNumber(value, curve_type, inverted) )
// value is the value within the range to be calculated
// curve_type is the type of response curve.
// Curve types: RangedNumber.LINEAR, RangedNumber.EXPONENTIAL, RangedNumber.POWERED
// inverted is a boolean flag. True if the inverted response is required

I have put together two demos to show the RangedNumber class in action:

Firstly using a Slider component. Grab the slider and watch how the markers are represented on all the displayed response curves.

A demonstration of how to implement non-linear response curves

Now here is the same demo but this time using a TouchPad. Click on the touchpad to engage. In this demo horizontal movement controls the standard curves and vertical the inverted.

How to implement non-linear response curves with a touchpad

The source for these demos and the Ranged Number class can be found here: Ranged Number ZIP


Gradients and masks in actionscript

Quick post to describe how to apply a gradient mask to a display object in AS3 (& AS2).

#1 Put your gradient mask on the stage – lets call it gmask
#2 Put the object to be masked on the stage.
#3 Set both the mask and the ‘object to be masked’ to cacheAsBitmap
#4 Apply the mask to the object

In #AS3
gmask.cacheAsBitmap = true
obj_to_be_masked.cacheAsBitmap = true
obj_to_be_masked.mask =gmask

In #AS2
gmask.cacheAsBitmap = true
obj_to_be_masked.cacheAsBitmap = true

It really is as simple as this.
Note to designers: Gradient masks can’t obviously be done directly from the IDE (see below), but these three lines can be placed on the timeline if so desired.

To put a gradient mask on dynamic text you will need to place the text within a container (movieclip/sprite) and mask that.

The object to be masked can also contain animation, text or video though this will require a bit more processor as the bitmap will need to redraw on each frame. Often this is well worth it as the effect can be great.

There is a way of achieving this same effect with no code at all and here it is:

#1 Put your gradient mask on the stage – lets call it gmask
#2 Put the object to be masked on the stage.
#3 Put both of these items into a movieclip/sprite (the container) making sure the mask is on a layer above the object
#4 Give the mask a blend mode of ‘Alpha’
#5 Give the ‘container’ a blend mode of ‘Layer’

And there you have it. Gradient masking achieved with blendModes and absolutely no code.

Benchmarking the two gradient mask methods:
I used each method to mask an embedded video – then placed an instance on the display list and ran at varying frame rates.
Initially there was negligible difference between the code and blend mask methods. I ramped up the FPS to 120 and put four instances of the video on screen. With this set up the code method (cacheAsBitmap) was up to 4% faster than the blendMode Mask method.

Conclusion: The code method is faster but very marginally. If you are desperate for a bit of extra juice go with code.


Collision Detection and Bounce Calculation using Colour Maps (part 1)

Here is a method I developed for a game I produced last year. I had three days, and a top down ball bouncing game with multiple levels to render. Initially I thought I’d use box2D, zero out the gravity, and then build the scenes as box2D models. This looked like taking far too long to create so I needed a quick fire solution. Then it dawned on me: Colour Maps (or to you chaps over the pond Color Maps).

Now Colour Maps are nothing new, but my idea adds to the technique.

Colour Mapping means you can build a map of your game scene with various colours representing the walls and objects. To test whether you have collided with an object, instead of numerous intersect calculations you can just test the colour of the pixel(s) underneath your character.

I realised that if I added a sprite graphic for my ball to the colour map using the Blend Mode ‘add’ then I could see collision. So if I make all the static scene furniture red (0xFF0000) and the ball sprite green (0x00FF00), when they overlap the intersection area becomes yellow.

Blend Mode collision detection

Blend Mode collision detection

So how does this help? I calculated that by using getColorBounds on the intersect yellow, I can draw a line from the centre of the rectangle to the centre of the ball. This now becomes the reflection point. I can reflect the angle of bounce against this to give a very accurate result.

Calculate the angle of reflection

Calculate the angle of reflection

OK. So the method will bounce from a partial intersection – but this means that we are calculating the bounce from a ball embedded within the border/scene furniture. I have improved this by calculating the ball path using a recursive method. The function backtracks to where the edge of the ball touches the furniture and then recalculates the path for the remaining distance to be travelled on the current iteration.
The Colour Map Bounce system in action

The Colour Map Bounce system in action

Here is a link to a quick demo of the method in action. Demo

Source and example usage is to follow in part 2.


Fastest Way to Copy An Array: Concat() or Slice(0)

What is the fastest way to copy an array? Concat or Slice? There is only one way to find out. FIGHT!

OK, so we can dismiss any kind of for-loop – far too slow, so that leaves us with:
1) array.concat() – i.e. concatenate an array onto nothing and deliver that as a new array.
2) array.slice(0) – i.e. return a new array consisting of all of the elements of the old array – from 0 till the end (up to a max of 16777215)

I’ve set up an array with a cool 1million entries (ok, it is not big, and it is not clever so it certainly isn’t cool). I need to copy this. The following code executes each method once on every iteration. It keeps a running total and records the average time each takes. I’ve limited the code to 100 iterations.

import flash.display.Sprite;
import flash.text.TextField;
import flash.utils.*;
public class TestConcat extends Sprite
private var iteration_count:int=0
private var concat_total:int=0
private var slice_total:int=0
private var clone_total:int=0
private var tf:TextField = new TextField()
private var test_array:Array = [];

public function TestConcat():void
tf.x = tf.y = 100; tf.width = 600;

//Set up array to copy
for(var i:int = 0; i < 1000000; i++) test_array.push(i);
//Mouse click to rerun test
stage.addEventListener(MouseEvent.CLICK, go);
//First run

private function go(e:Event = null):void
addEventListener(Event.ENTER_FRAME, iterate)

//Loop through tests
private function iterate(e:Event=null):void
concat_total +=testConcat()
slice_total += testSlice()
clone_total += testByteArrayClone()
tf.text = "Av. Concat time=" + (concat_total / iteration_count)
+ "ms Av. Slice time=" + (slice_total / iteration_count)
+ "ms Av. BA Clone time=" + (clone_total / iteration_count) + "ms";
if(iteration_count<99) removeEventListener(Event.ENTER_FRAME,iterate)

//test array slice
private function testSlice():int
var time_slice_start:Number = getTimer();
var slice_copy:Array = test_array.slice(0);
return getTimer()-time_slice_start

//test array concat
private function testConcat():int
var time_concat_start:Number = getTimer();
var concat_copy:Array = test_array.concat();
return getTimer()-time_concat_start

//test BA Clone method
private function testByteArrayClone():int
var time_concat_start:Number = getTimer();
var concat_copy:Array = clone(test_array);
return getTimer()-time_concat_start

//Clone method for Deep Objects(via Bruno)
private function clone(source:Object):*
var myBA:ByteArray = new ByteArray();
myBA.position = 0;

On my laptop I’m clocking the concat at 14ms and the slice at over 29ms.

So a conclusive result. concat is twice the speed (with large arrays – the difference diminishes considerably with smaller arrays)

Give the code a few run throughs and see what you get. Let me know if your results are markedly different.

I have updated the code and added a swf to try out here and the source code here

Fastest way to copy an array

Test the array copy for yourself

I’ve also added in a test for the Byte Array Clone method suggested by Bruno (see his comments below). This method seems a great one for copying ‘deep’ arrays – arrays of complex objects (arrays, objects or other types). In this context and test (copying shallow arrays) the instantiation, writing and reading adds too much overhead. I’ll need to test this in a useful context: with deep arrays.

Demo: Array Copy test


Simple Sideways-Scrolling Carousel

Not another carousel! Well yes. Posting this for storage really, the only real new thing added here is the method for scaling up the focus object.

On every enter frame event, each item in the list is checked to see if it is in the focus range (the centre of the visible area and a selected distance either side). If so, then the absolute position is calculated against the centre point. Now the scale and blur are added accordingly.

The class is encapsulated and easy to instantiate:

_carousel=new Carousel()
_carousel.init(area_width, area_height, range_pc, margin, min_scale, item_array, blur_on, blur_amt)

area_width – width of the visible carousel area
area_height – height of the visible carousel area
range_pc – the percent of area either side of the centre point to use as the focus range (0.1 – 1.0)
margin – the margin bordering each item on the carousel
min_scale – scale that items outside of the range reduce to (0.1 – 1.0)
item_array – array of sprites/movieclips buttons
blur_on – true=blur on, false=blur off
blur_amt – amount of blur to apply to the items out of range

Simple AS3 Carousel

AS3 Simple Carousel

A demo has been set up and can be seen here

The items in the carousel can be anything from simple pictures or buttons to more complex interactive movieclips.

There are three main interactive methods in the Carousel class:
scrollLeft() / scrollRight() – Increment along the list
gotoItem(index) – scroll to the selected item (where index is the item array reference for the item)

I have only added the functions required for my current project, but it should be very simple to add extra functionality such as looped content, reflections, etc.

Source files


Keeping Lip-Sync in Sync

I’m currently working on a project where I have been handed a lot of movieclips with animated mouths to be sync-ed with spoken audio triggered from the library. Each sentence had been put together in a separate movieclip. Obviously this method exposes the frame rate on slow computers leading to loss of lip-synchronisation. I was told to go through all of the moveiclips and add the audio to the timeline – a very inelegant solution that would take a lot of time with poor results.

I came up with a simple solution that basically just pushes the playhead forward everytime it drops out of sync. I use the frame rate and getTimer to work out where the playhead should be on each iteration. If the playhead drops then it is moved to the position it should be at.

Very simple – saved me a lot of time.

private const FPS:int = 30//Current frame rate
private const ERROR_MARGIN:int=1
private var start_time:int
private var last_frame:int=0//Keep track of last frame to see if mc has stopped playing
private var loop_started:Boolean=false

public function sayPhrase(phrase:String) : void
last_frame=0 //reset last frame
start_time = getTimer()

private function lipSyncTracking(e:Event = null):void
if (mouth_mc.mouth)
var cframe:int = mouth_mc.mouth.currentFrame //get the current frame
var ctime:int = getTimer() //current time
var time_expired:Number = (ctime – start_time )
var target_frame:int = Math.floor((FPS/1000)*time_expired)
if(target_frame>1 && cframe>1)loop_started=true //need to check for looping
if (cframe == last_frame || (cframe==1 && loop_started))
{//MC must have stopped or looped back to beginning
{//If frame is out by the margin of error then correct
if (target_frame >= cframe + ERROR_MARGIN)

last_frame = cframe


Jonga3D: Testing Jiglib with Away3D

I just wanted to test the (newly available in AS3) 3D Physics engine Jiglib.

My first test for Box2d was to build a Jenga-style game (Jonga) so I thought I would do the same here. Only a quickie this. I wanted to see if Jiglib would be able to allow ‘rigid boides’ in a 3D environment with good performance. I know we are limited in Flash so was prepared for a few foibles.

Jiglib has been put to great use in other formats so I had high hopes for its Flash port.

Now I have only given the library 3 or 4 hours of play but my one major probelm so far is the frame rate hit. In Jonga3d I have had to reduce the number of blocks to 15 (5 layers – I wanted 15 (45 blocks)) and I am still only getting 6fps. I was really hoping for more.

I’m not complaining too much, a 3d physics engine is a complicated library to pull off – I’m just waiting for the day I can build an unfettered 3d environment with a workable physics engine.

Jiglib has a few other problems – the jiggling static box for example – but these are understandable for v0.25


Testing Jiblib: Jonga3D

In the test I didn’t get around to implementing the mouse drag interactions so to see a collapse use the arrow keys to control the sphere – ram it into the stack.

I am using Jiglib 0.25 – Away3d version and Away3D 2.3 (Link)
I use SwfProfiler to track the fps.


Thanks to SleepyDesign for getting the ball rolling on this.


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