60fps or Bust!
Flash Game Performance Tuning from A to Z
Andy Hall
Adobe Japan
© 2012 Adobe Systems Incorporated. All Rights Reserved.

Andy Hall アンディ ホール
Game Evangelist ゲームエバンジェリスト
Adobe Japan アドビ システムズ 株式会社
@fenomas
© 2012 Adobe Systems Incorporated. All Rights Reserved.

Agenda
• Overview
• Tuning ActionScript 3.0
• Flash Player Internals
• Rendering Optimization
• Upcoming topics
© 2012 Adobe Systems Incorporated. All Rights Reserved.

Principles of Optimization
“Premature
optimization is the
root of all evil”
Donald Knuth
（早すぎる最適化は諸悪の根源）
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Optimization Flow
Build for
Architect for Optimize!
speed and
performance (only the slow parts)
correctness
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Metrics
To optimize you need measurable metrics!
• FPS
• Memory usage
• CPU usage
• Bandwidth?
• Battery usage?
• etc...
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Profiling
Now: Soon:
Flash Builder 4.6 Profiler Codename “Monocle”
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TUNING ACTIONSCRIPT
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Tuning ActionScript 3.0
Caveats:
• Often not as important
as rendering
• Beware of low-impact
“tips and tricks”
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The Basics
• Always use AS3.0
Always!
• Type everything
• Prefer Vector.<type> over
Array or Dictionary
Only in • Prefer String methods over RegExp
critical
areas • Be careful with E4X and XML
( )
• Callbacks are faster than Event
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Pooling
Instantiation can be expensive!
Pool or reuse objects to avoid the cost of frequent creation
and collection
• Static temps
• Object pooling
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Function Calls
Function calls can be expensive too.
Keep a shallow call stack and avoid recursion:
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Garbage Collections
Know your GC!
• Flash’s GC does both reference counting and
mark-sweep.
(If you want to tune memory usage, you need to understand these!)
• Use Monocle to find if GC is firing too often
• Pooling/reuse makes GC collection less frequent
• For large collections, prefer literals (String, int..) or plain
objects over complex objects (Sprite, Rectangle..)
© 2012 Adobe Systems Incorporated. All Rights Reserved.

Smart GC
Tell Flash when to trigger a GC!
Call this between levels, when the game pauses, etc.
Flash’s GC marks incrementally, and this command tells it to finish
marking and do a collection if a GC was already imminent. The
argument specifies how long you’re willing to wait for a GC:
imminence=0.99; // GC if ready now
imminence=0.01; // GC even if you need to pause a while
© 2012 Adobe Systems Incorporated. All Rights Reserved.

FLASH INTERNALS
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The big picture
// Flash’s internal loop (simplified)
while() {
sleep until (nextEvent OR externalEvent)
if ( various events pending ) {
handleEvents();
// handles Timer events,
// fills audio/video buffers
}
if ( time for next SWF frame ) {
parseSWFFrame();
executeActionScript();
}
if ( screen needs update ) {
updateScreen();
}
}
© 2012 Adobe Systems Incorporated. All Rights Reserved. Gory details: http://blog.kaourantin.net/?p=82

Flash’s Internal Loop
Handle Next SWF frame
various Rendering
events Execute scripts
sleep
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Point: Because of this, most
recurring scripts should be handled
in Event.ENTER_FRAME !
ENTER_FRAME
Handle Next SWF frame
external Rendering
events Execute scripts
sleep
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The Display List
Vector
shapes
Video
Bitmap
Display List
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Dirty Rectangles
“Dirty”
(redrawn)
(frame update)
Display List
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Display Planes
Vector
3D
Video
Display List
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Drawing Modes
wmode (Flash),
renderMode (AIR)
direct
GPU
gpu CPU
cpu Browser
Flash
Renderer
transparent
opaque
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RENDERING OPTIMIZATION
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Rendering Basics
The basics:
• Keep a shallow display list.
Reason: everything
in that rectangle
is getting redrawn
every frame! Display List
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Rendering Basics
More basics:
• Understand that certain features are just heavy!
• Bitmap Effects (shadow, glow, emboss...)
• Masks (inherently vector-based)
• Alpha channels
• Blend modes (add, multiply...)
and even...
• Embedded fonts (especially Japanese!)
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Rendering Basics
More basics:
• Keep extraneous stuff off the stage
• Use the right framerate
• Simplify vector shapes
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Stage Settings
• StageQuality.LOW:
Lower-quality vector shapes. Never anti-alias, never
smooth bitmaps.
• StageQuality.MEDIUM:
Better vectors. Some anti-aliasing but no bitmaps
smoothing. Default value for mobile devices.
• StageQuality.HIGH:
Always uses anti-aliasing. Uses smoothing on bitmaps
depending on whether the SWF is animating.
Default value on desktop PCs.
• StageQuality.BEST:
Best quality. Always anti-alias, always smooth bitmaps.
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Rendering Internals
Understand rasterization and the conditions
for cached bitmaps to get redrawn!
(Designers need to know this too!)
© 2012 Adobe Systems Incorporated. All Rights Reserved.

Bitmap Caching
• Lets complex assets
be rasterized once
instead of every frame.
• Turned on automatically if you use bitmap
effects
Caching is the single most important thing to
understand for tuning display list content!
© 2012 Adobe Systems Incorporated. All Rights Reserved.

Bitmap Caching
foo.cacheAsBitmap = true;
(redrawn)
(cached)
foo.cacheAsBitmapMatrix = new Matrix();
(cached)
(drawn with GPU)
(only in AIR!)
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Bitmap Caching
Use Monocle to see what’s being cached
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Rendering
One more technique:
Adjust visual effects at runtime!
500 particles 200 particles
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RENDERING MODELS
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Rendering Models
There are four main rendering models
in use today for Flash games.
1. Display List
2. GPU mode
3. Blitting
4. Stage3D
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1. Display List Rendering
• Plain vanilla flash content, made in Flash Pro
• Easiest to build – worst performance.
• Suitable for prototypes and light desktop content.
Bad for mobile! (because the GPU is not used)
• Your key tuning technique will be bitmap caching.
© 2012 Adobe Systems Incorporated. All Rights Reserved.

2. GPU Mode
• GPU mode is a publish setting available for AIR apps on
devices (Android and iOS)
• When selected, Flash uses the GPU – vectors and cached
surfaces are rendered through hardware.
• Can be very powerful with careful, correct use of
movieclip.cacheAsBitmapMatrix
• Powerful technique today, but not recommended for
new/future projects
© 2012 Adobe Systems Incorporated. All Rights Reserved.

GPU Mode Example
Monster Planet SMASH!
(GREE)
More info:
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3. Blitting
• Blitting refers to putting a Bitmap object on the stage for
your game area and manually drawing contents into it
with BitmapData.copyPixels().
• Hence, you manage your own rendering, caching, etc.
• Can be very fast in certain restricted cases
• Does not scale up for retina/hi-res devices!
© 2012 Adobe Systems Incorporated. All Rights Reserved.

4. Stage3D
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4. Stage3D
• New feature from Flash 11.0, allowing ActionScript to
load shader programs directly to the GPU.
• Based on AGAL (Adobe Graphics Assembly Language)
• AGAL looks like this: m44 op, va0, vc0
dp4 op.x, va0, vc0
dp4 op.y, va0, vc1
• You probably want dp4 op.z, va0, vc2
dp4 op.w, va0, vc3
to use a 2D/3D library! m44 op, va0, vc0
mov v0, va1
(It’s dangerous to go alone!)
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4. Stage3D
(Take this!)
• Two officially supported libraries:
• Starling (2D)
• Away3D
• And many, many more...
N2D2
Genome2D
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Stage3D examples
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NEW / FUTURE TOPICS
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AS3 Workers
create
Main Background
Worker Worker
MessageChannel
(regular API (some
Flash player) limitations)
mutex
Shared
memory
© 2012 Adobe Systems Incorporated. All Rights Reserved.

AS3 Workers
create
Main Background
Worker Worker
MessageChannel
(regular API (some
Flash player) limitations)
mutex
Shared
memory
© 2012 Adobe Systems Incorporated. All Rights Reserved.

ASC2.0
• All new ActionScript compiler!
• Included with the Flash Builder 4.7 preview:
http://labs.adobe.com/technologies/flashbuilder4-7/
• Key features:
• Faster compiles! More optimized bytecode!
• Error messages localized to JA, FR, ZH
• Inline functions, get/setters (when possible) (use –inline arg)
• goto statement (!?!?!?)
• Details: http://www.bytearray.org/?p=4789
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Longer term
Project Better Better
Monocle! Flash Pro! ActionScript!
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Thanks!
andhall@adobe.com
@fenomas
© 2012 Adobe Systems Incorporated. All Rights Reserved.

© 2012 Adobe Systems Incorporated. All Rights Reserved.