Programming games

1
Programming games

• Registration experiment. Drawing.
• Equations of motion.
• Video.
• Homework Finish cannonball. Start Video.

2
Registration/origin

• Defines the position of a movie clip
• Origin and transform point may be different. Can
  adjust either one.
• Not necessarily the center of occupied pixels of
  the object
• YOU decide where you want that to be.
• Remember if/when you change a symbol in the
  Library, it changes everywhere!
• unlike changing the contents of a frame

3
Advice

• Experiment
• create simple movie clips in the Library
• Brush size. Stroke vs Fill.
• Move/make instances of them to the Stage
• Observe the positions (X, Y) in the Property
  Panel
• Notice the origin (cross-hairs) and the
  transformation point (empty circle)
• Write trace statements to reveal positions
  (properties .x and .y)

4
Equations of motion

• displacement time velocity
• Traveling 20 miles/hour for 2 hours
• 40 miles
• Traveling 30 miles/hour for .5 hours???
• Traveling 40 miles/hour for .75 hours???

5
Equations of motion

• change in velocity time acceleration
• Traveling at 30 miles/hour, accelerating
  (changing velocity) 2mile/hour/minute, then after
  5 minutes, now going 30 10 miles/hour 40
  miles/hour

6
Discrete calculations

• Going one speed at the start of an interval and a
  different speed at the end, calculate
  displacement using the average
• displacement
• time (vspeed1 vspeed2).5

7
Ballistics

• Initial movement
• cannonball leaves cannon at initial speed and
  direction ('at an angle')
• BUT we can only move things by moving them
  horizontally and vertically!
• Also, the vertical velocity will change because
  of gravity

8
Syntax note

• The brackets make multiple statements the
  equivalent of a single statement
• You may see
• if (condition) statement
• But using the brackets means you won't make a
  mistake if/when you add a statement
• if (condition)

9
Data types

• Numbers are not character strings (text)
• The number 12 is different from '12'.
• The latter is the character string numeral 1
  followed by numeral 2.
• Contents of text boxes are text, that is,
  character strings.
• If your player is inputting a speed or an angle,
  your code must convert this to a number.
• Multiplying will do it! (and you probably didn't
  notice that a conversion (also called a cast) was
  taking place.

10
Compiling

• The Flash program translates / combines all the
  coding to make the thing that runs (the .swf
  file).
• This translation process is called compiling.
  Errors found during it are called compiler
  errors.
• Publishing is doing the translation and producing
  an .html file and a .swf file. You upload both
  (plus in certain situations another file) to the
  server. Links are to the .html file.

11
Flash .swf files

• are relatively small because
• they make use of the Flash plugin. The code in
  your program includes calls to routines in the
  plugin.
• Much of the graphics may be vector graphics
  stored as formulas and not bit maps.
• Check out the file sizes.

12
Common problems

• Copying and pasting anything that looks like code
  from tutorial to your project.
• NOT naming things or being inconsistent.
• Instance name is what matters for the coding
• If there are compiler errors, it will not work.

13
Video in Flash

• More than one way to incorporate video into Flash
  
• bring in whole video that plays along with the
  frames. We will not use this way!
• For this class, we will use a FLVPlayback object
• Requires an import statement
• This allows shorthand names for built-in parts of
  ActionScript
• Requires statement adding to Display list
• Objects created in code (as opposed to put
  directly on the Stage) need to be added to the
  Display list to be shown.

14
Videos

• Different types of videos (like different types
  of images)
• Flash video playback requires videos of type .flv
• Can use Adobe Flash Media Encoder (part of the
  Adobe CS4 package) to take one type of video and
  produce an flv

15
Basic coding

• import fl.video. //get the builtin classes
• var flvFLVPlayback //set up variable
• flv new FLVPlayback() //give it a value
• flv.source "dickey2.flv" //set source attribute
• flv.x 10 //position on screen horizontally
• flv.y 10 // and vertically
• addChild(flv) // make visible by adding to
  // Display list

16
addChild

• Adds to the Display list.
• In my tutorials, you also will seecanvass.addChil
  d(stuff)
• This adds the newly created stuff object as a
  child of canvass. This will determine the
  positioning of stuff.

17
Skins

• These are the video clip controls.
• Appropriate when you want to give the
  player/user/customer more controls
• You may choose NOT to give user control in
  certain cases
• Many choices
• USE HELP!
• Requires you to upload an .swf file to the
  server.

18
Files for your application

• Your application will consist of the following
  files. Say your application is called mywork.fla
• mywork.html
• mywork.sw
• For each video f1.flv, f2.flv, etc. The names
  f1, f2, need to be replaced by the names you gave
  the video. (Remember no blanks!)
• For each skin the name of the skin file
  xxxx.swf

19
Video examples

• Play back single video
• Play back choice of video (two ways)
• Bouncing Ball
• Used mask to make the playback a circle
• Jigsaw puzzle turning into video
• ???

20
Ballot example

• I had a request from stranger Sunday before
  election
• Radio buttons
• SharedObject
• This is the equivalent of cookies a way to store
  data on the client (player) computer.
• Dynamically created text field

21
Consider

• You can use SharedObject to save information on
  the client (user, player, customer) computer.
• Score (last score)
• Video choice
• Name

22
Video

• Use camera
• Need to upload
• If not .flv, use Flash Media encoder to made an
  .flv
• Use keepvid.com (or other sites) to download
  video from YouTube
• Note I prefer you to use your own. If you use
  someone else's, you must make 'value-add' to the
  project.

23
Homework

• Finish Cannonball (Due in 1 week)
• Start Video project. Do something simple. You can
  build on it for the final project.
• Buttons for choosing
• With or without skin
• With saving using SharedObject
• Video as part of other project
• Bouncing ball
• Rock-paper-scissors
• Cannonball
• ??? Ask me for help