Programming games

1
Programming games

• Show final project. General review
• Homework finish project, look over study
  guide. Make office appointment for help.

2
Files

• Giving your user a way to download a file
• I did this by adding on to the playing sound file
  example. IT CAN BE ANY FILE!
• Need to test this on the server, but you can look
  at the source code (the .fla file)
• I did NOT put in code to monitor the process and
  report back errors!!!

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from the code

• var downloadURLURLRequest
• var fileNameString lastplayed
• var fileFileReference
• downloadURL new URLRequest()
• downloadURL.url lastplayed
• file new FileReference()
• file.download(downloadURL, fileName)

4
Jargon

• There IS jargon in computing. It pays to learn
  it.
• The jargon is mostly English words with more
  specific meaning.
• Examples
• Event event handling
• Function
• Variable
• Instance

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Comment

• Much of jargon is common to other computer
  languages
• You have seen similarities in syntax between
  JavaScript and ActionScript
• Note ActionScript 3.0 actually is MORE like Java
  than JavaScript
• Strong-typing (require declaration of datatype
  and don't let it change!)
• var courseString "MAT1420.45"
• import

6
Building an application

• Planning
• Design
• Choosing technologies
• This is NOT part of most college courses, but may
  be something you will need to do
• Most projects are part of / relate to other
  projects
• Implementation
• Testing
• Refinement
• Distribute / deliver / install

This is called the waterfall model. Real process
may not be so neat. Constant iteration.
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More

• Most projects are team projects
• Butdon't specialize / limit what you want to
  learn practice
• Most of my other courses feature team work.
• Fall 2011 Creating Databases for Web
  Applications
• Spring 2012 Robotics

8
Creating games general

• Prepare 'board'
• static material
• dynamic material
• things that move
• things that change
• Define (internal) information. This can be
  complex!
• variables
• strings, numbers, booleans.
• arrays
• objects (properties and methods)
• Implement player moves other action
• identify/define events and program event handlers
• include random (stochastic) elements
• implement logic of game

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Creating games Flash

• Prepare board
• Prepare symbols
• graphics
• instances
• buttons
• Prepare stage
• move instances of symbols components to stage
• this may be 'off-stage', to be re-positioned by
  code
• draw directly on stage (including moving graphic
  symbols to stage)
• text fields on stage
• static, dynamic, input

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Creating games Flash

• Define (internal) information
• variables
• global variables defined outside of functions,
  in main movie and
• local variables variables defined in functions
• variables in instances
• programmer defined. See next.
• Datatypes strings, numbers, booleans
• Composite types arrays, objects

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Creating Games Flash

• Determine built-in classes (coding) to be used
• For example playback of video
• Determine what classes YOU have written
  previously can be re-used
• Piece.as can be used for any jigsaw!
• Determine what new classes are to be defined
• External .as file(s)

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Instances

• Built-in attributes aka built-in properties
• ball.x,
• ball.y
• target.rotation
• globe.alpha
• block.width
• block.height
• others

ActionScript 3.0. drops the underscore _ you will
see in old Flash examples.
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Creating games Flash

• Implement player moves and other actions
• ActionScript in frames
• ActionScript for instances
• onclipEvent
• on(release)
• ActionScript may also be in frames of movie clip
  symbols brought into main movie
• Target in cannonball had stop()
• Other?

"depreciated". Should use procedural/frame code
to set up event handling
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There will be another version of ActionScript

• Basic concepts the same!
• Functions, naming, logic, variables.
• Event handling
• Use Help
• May need to be on-line

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Creating games logic

• ActionScript closely resembles other languages
• statements
• assignment
• if (condition)
• if (condition) else
• for (initializationcondition increment)
  
• switch

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Logic object view

• (If you study OOPL, such as Java)
• Logic sometimes is implemented more-or-less
  implicitly.
• In objects (movie clip instances are objects),
  the programmer can define methods each different
  types (sub classes) so the 'if' is done by which
  method. Example
• Method to calculate power done one way for super
  hero, another way for mortal.
• Shipping cost free for preferred customer, a
  calculation for regular customer.

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Random

• aka pseudo-random because the random values are
  produced by a well-defined procedure. They
  appear random.
• Math.random() produces a number (fraction) from
  zero up to but not including 1.
• Math.floor(Math.random() 6) produces one of
  0,1,2,3,4,5

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Functions

• Functions are ways to package code to be used
  (and re-used)
• Function definitions specify name and parameters.
  
• Variables defined (var statement) within the
  function cannot be accessed outside the function.

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Definitions

• Remember questions about function, variable,
  array refer to technical meaning (programming
  jargon) NOT the English meaning of the term.
• A function in programming is a construct that
  sets up a sequence of statements, along with
  definition of parameters. The coding for function
  definition is function fn (parameter name(s))
  code
• coding for a call to a function uses its name
  followed by ( the parameter(s)) and closing )

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Definitions, continued

• A variable in programming is associating a name
  with a value. The value can change! Using the
  name will return the current value.
• An array in programming is a particular type of
  value, namely a set of values. The common form of
  array is a sequence of values. To get the
  individual values, you write code with
  arraynameindexvalue

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Notation

• Programming uses a variety of symbols
• ( and ) are used to
• control order of evaluation a(bc)
• hold the parameters in a function definition
• hold the parameters in a function call
• hold the condition in an if statement
• hold the condition in a while statement or switch
  statement
• hold the set up values for a for loop

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Notation, cont.

• and are used
• hold the body of the function in a function
  definition
• hold the if true clause and the else clause
• hold the clause in a while or for loop
• hold the clause in a for loop
• and are used
• setting up arrays, as in var ma
• indexing arrays

23
Timing

• For internal calculations and for display
• Use playing of frames (standard is 12 fps)
• Use Timer object
• See bouncing ball, bouncing stuff, cannonball,
  shooter

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Flash issues

• Main movie and movie clip instances each loop
  from frame to frame in main movie AND each movie
  clip instances unless there are stop() or
  gotoAndPlay() statements
• Functions and variables (outside of functions)
  are accessible by name of movie instance.
• suggestion put all functions and main movie
  variables in first frame, actions layer.
• Material on stage in a frame (and in a layer)
• layers are defined to layer graphical material
• organize actionscript, graphics, frame labels

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Flash possibilities

• For games, more likely to have fewer frames, more
  movement by program control
• Remember cel animation vs computed animation
  Applications may use both!
• Game/application can contain many movie clip
  instances
• Use frame code or code in external .as files to
  create objects
• Need to addDisplay
• movie clip symbols may be simple or complex (for
  example, multi-frame)
• movie clip instances can have actions

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3 D

• Instead of locating objects in/on 2 dimensional
  Stage, position in 3 dimensions
• also may need to orient objects
• position and orient camera/eye to do calculation
  for what you see
• 3D in Flash is only partial 3-D. The display list
  and layers overrides the 3D positioning.
• I expect improved 3D is coming.

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Reprise for games

• What's on the board
• static
• dynamic (changing)
• What is the information
• What are the events and what should be the
  response (event handler)? What is the logic of
  the game?
• capture and respond to player moves
• respond to other events (for example, timed
  events)

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Flash

• Publish application
• Use .fla file and, possibly. .as files
• produces .html and .swf files
• One copy of AS.RunActiveContent.js needed
• Need to upload both .html and .swf
• If you are using any .flv files or .mpg, need to
  upload them and use correct reference.
• Warning the published application has smaller
  screen than the development application (.fla
  file)

29
Trigonometry!!!

• Go from angle to position and position to angle
• used in ballistics, robotics, driving, etc.

R
Y
Y R sin(a) X R cos(a) a atan(Y/X)
a
X
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Degrees and radians

• How to measure an angle?
• Traditional way 360 degrees is a full circle
• 90 degrees is a 'right angle'
• 180 degrees is a half circle. 'Do a 180' means to
  turn around.
• Alternative measure a circle is PI (3.14159)
  worth of radians. This is an intrinsic measure.
• Conversion formula
• radians (PI/180) degrees
• Flash uses both!!!! cannon.rotation takes
  degrees, the Math trig methods use radians.

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Positions

• THE position of an object in Flash and other
  languages x, y and z values.
• Is dragon near enough to the gold ? Say within
  gap both horizontally and vertically
• What if it can be to the right or the left and
  above or below?Use Math.abs()
  Math.abs(30)Math.abs(-30)
• if ((Math.abs(dragon.x-gold.x)ltgap)(Math.abs(dr
  agon.y-gold.y)))

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Collisions

• Flash provides two methods
• dragon.hitTestPoint(gold.x,gold.y,true) checks if
  the single point gold.x, gold.y overlaps with any
  occupied pixel of the dragon
• dragon.hitTestObject(gold) checks if the bounding
  box containing the dragon overlaps with the
  bounding box containing the gold.

33
3D modeling

• Build a virtual world
• approximate shapes using polyhedra (facetted
  objects)
• surface textures
• special procedures (e.g., fractals) for objects
  in nature
• Move objects
• articulated (jointed) motions
• expression
• Render objects
• eye (camera), focal point, lighting
• Products to do these things but imagination AND
  knowledge of mathematics physics is helpful.
• Try Google SketchUP (free version)

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http//Processing.org

• Language built on Java for graphics, physical
  computing, other.
• My initial attemptshttp//faculty.purchase.edu/j
  eanine.meyer/processing

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Programming Courses

• Math/CS (often cross-listed with New Media)
• CS I programming in Processing!, every semester
• CS II every Spring
• Physical Computing every Fall
• Creating Databases for Web application, Fall 2011
• Robotics, Spring 2012
• Rotating courses Games for Change, Mobile Media,
  Social Software, Creating User Interfaces, ???

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Homework

• Finish project
• Upload
• Review study guide
• Review lecture charts
• Come to office for help.
• Participate in study session.