Visual Basic Games: Week 4

1
Visual Basic Games Week 4

• Recap
• Parallel structures
• Initialization
• Prepare for Memory
• Scoring
• Shuffling
• Homework when ready, move on to next
  game/chapter.

2
First 3 projects

• What were the controls?
• What were the events (what event procedures did
  you write)?
• What global variables were required?
• "State of the game" consists of what is present
  on the screen plus any global variables.

3
Statements

• Assignment statement
• intTotal intDie1 intDie2
• For/Next
• For I 0 to 6
• imgDie(I).Visible False
• Next I
• Select Case
• Select Case intTotal
• Case intPointnum
• lblstatus "You Win"
• blnfirstmove true
• Case 7
• lblstatus "You Lose"
• blnfirstmove true
• End Select
• If/Else/End If or IF/End If

4
Another compound statement Do While

• For/Next does the statements 'in' the loop a
  certain number of times (though it can be based
  on variables)
• Do While does the statements as long as a
  condition is true
• Do while condition
• Loop

5
Parallel structures

• In mix match, the listbox items responded to
  the elements in the control arrays
• Sets of sets here the items in the lstHats
  listbox corresponded to the elements of the
  imgHats control array floppy hat ??
  imgHats(0)
• In memory, control array holding file names and a
  control array of images.
• Using parallel structures is a very common
  technique.
• YOU make it happen.

6
Is there another way?

• Using parallel structures, call them implicit
  parallel structures, is necessary because the
  control objects are distinct and cant be linked
  except by your code.
• For internal variables, there is something called
  types that puts corresponding data together
• Private Type bestdata
• bname As String 20
• bscore As Integer
• End Type

7
Initialization

• Start of execution (Run menu / Start or the start
  icon)
• Form_Load
• Form_Activate (used in Quiz). Necessary when
  switching between forms.
• New game
• Probably command button Click
• New move
• You have to understand, plan and program. Often
  need to clear / tidy up board. Set variables to 0
  or the empty string OR not (wait for first/next
  action to set values).

8
Initialization

• What was required initialization in
• Rock-paper-scissors
• Mix and match
• Chance

9
Ideas to improve/enhance interface

• rock paper scissors
• add to or replace text with images
• player and computer?
• score
• ?
• mix and match
• better imagesbetter fit of images
• random feature?
• ?
• chance
• rolling dice and/or random locations
• remove text?
• score
• ?

10
Memory / Concentration Game

• Board consists of 16 cards, all showing blank
  side.
• Click on a card it is 'turned over'. Click on a
  second card it is 'turned over'. If images
  match, both cards are removed, otherwise, cards
  are 'flipped back'.
• Game is over when all matches made.

11
Implementation Requirements

• 8 pairs of images plus blank images for the
  "backs"
• names of imagesall comparisons are done in terms
  of the names
• Pause time before cards removed or flipped back

12
What are events

• for which you must write event procedures?

13
Event procedures

• Form_load
• set up shuffle cards. This will be done using
  user-defined procedure so you don't have to write
  the code twice
• Click on image
• will need to distinguish a first and a second
  turn
• New game button
• restore cards and shuffle
• other buttons (Help, End)

14
User (this means you, the programmer) defined
procedure

• Unlike event procedures, you name it as well as
  program it. You also issue calls to it.
• Private Sub delay(interval as Single)
• Dim sngStart as Single
• sngStart Timer
• Do While Timer lt (sngStart interval)
• DoEvents
• Loop
• End Sub
• call delay(1)

built-in function. Returns seconds since midnight
let's computer to other things, while waiting
15
About images

• Our implementation of memory is (purposely)
  different from mix match and chance.
• LoadPicture method is used to put the appropriate
  image into the control when required. This means
  that the images must be in the same drive/same
  folder as the program.

16
Scoring

• Can just use visible label, assume lblScore is
  the label control and intNewScore the internal
  integer variable holding the addition to the
  score
• Initialize
• lblScore.Caption 0
• Update
• intOldscore Val(lblScore.Caption)
• lblScore.Caption Format(intNewScore
  intOldScore, 0)
• Note this works even if intNewScore is negative.
• The 0 makes sure 0 appears.
• What would be the changes if new scores were
  money AND if there could be scores with
  fractional parts?

17
Shuffling

• Have an array of N items of some data type
• Want to shuffle, that is, re-arrange the values
  to be randomly sorted.
• What is the criteria for success?
• Answer equal likelihood of any of the N possible
  permutations.
• How to do it?
• Using Randomize, Rnd, etc.

18
A Shuffle method

• 6 things (why six? Because I have a single die)
• How many permutations are possible?
• Start first with the last position. Pick
  randomly one of the first six to swap this one.
  Note so one possibility is swapping with itself,
  for no change.
• Now move to next to last (5th). Pick randomly one
  of the first 5 to swap with this one.

19
Construct deck of cards

• strSuits (1 to 4) as String
• strSuits(1) hearts
• strSuits(2) spades
• strSuits(3) diamonds
• strSuits(4) clubs
• strFaces(1 to 13) as String
• What do I need to do to produce A, 1 , K
  ??

20
Produce deck

• Sub setupdeck()
• Dim i As Integer, j As Integer, k As Integer
• k 1
• For i 1 To 4
• For j 1 To 13
• strDeck(k) strSuits(i) strValue(j)
• k k 1
• Next j
• Next i
• End Sub

21
Swapping

• Whenever you swap two things, you will need a
  temporary variable
• thing1, thing2, holder each variables holding a
  value. An assignment statement takes the value
  of the right side, in this case, the value in
  that variable and puts it in (assigned it to) the
  variable named by the left side.
• holder thing1
• thing1 thing2
• thing2 holder

22
Shuffle

• Private Sub cmdShuffle_Click()
• Dim i As Integer, k As Integer
• Dim holder As String
• For i 52 To 1 Step -1
• k Int(Rnd i) 1 ' k is random choice 1 to
  i
• holder strDeck(k)
• strDeck(k) strDeck(i)
• strDeck(i) holder
• 'swapped values in k and i positions of strDeck
  array
• Next i
• End Sub

23
Homework

• Read chapter 4 (Memory/Concentration) and start
  implementing it
• You can make your own images!