Microsoft Small Basic

Program Listing: JMB267

List Program

' TODO: Avoid Snake when adding and moving food

' Global layout variables
gw = 640
gh = 480
titleRegion = 30

SetupWindow()
SetupGlobals()
InitGame()

Sub GameLoop
If (run) Then
MoveSnake()
AdjustTimer()
Endif
DrawSnake()
UpdateGui()
EndSub

Sub InitGame
Timer.Interval = intervalTime
DrawGrid()
SetupGUI()
CreateSnake()
ResetSnake()
DrawSnake()
MoveFood()
EndSub

Sub CreateSnake
' Starting size of Snake
numSegments = 50
visibleSegments = 10
snakeDirection = north

' Snake attributes for 2D Array which holds all the snake data
segment = 0
x = 1
y = 2

' Snake Direction vectors for head
snakeVX = 0
snakeVY = 0

segRadius = 10
startX = Math.Round(gridWidth/2)
startY = Math.Round(gridHeight/2)

GraphicsWindow.PenColor = "Transparent"

For s = 1 To numSegments
If s = 1 Then
GraphicsWindow.BrushColor = "Red"
Else
GraphicsWindow.BrushColor = "Green"
EndIf
tempSegment = Shapes.AddEllipse(segRadius * 2, segRadius * 2)
Shapes.HideShape(tempSegment)
snake[s][segment] = tempSegment
EndFor
EndSub




Sub ResetSnake
For s = 1 To numSegments
snake[s][x] = startX
snake[s][y] = startY + s
If (s <= visibleSegments) Then
Shapes.ShowShape(snake[s][segment])
Else
Shapes.HideShape(snake[s][segment])
EndIf
EndFor
EndSub


Sub DrawSnake
For iD = 1 To visibleSegments
tempShape = snake[iD][segment]
tempX = snake[iD][x] * gridSize
tempY = (snake[iD][y] * gridSize) + titleRegion
Shapes.Move(tempShape, tempX, tempY)
EndFor
Shapes.ShowShape(snake[visibleSegments][segment])
EndSub

Sub MoveSnake
For iM = numSegments To 2 Step -1
snake[iM][x] = snake[im-1][x]
snake[im][y] = snake[im-1][y]
EndFor
If (snakeDirection = north) Then
snakeVX = 0
snakeVY = -1
ElseIf (snakeDirection = east) Then
snakeVX = 1
snakeVY = 0
ElseIf (snakeDirection = south) Then
snakeVX = 0
snakeVY = 1
ElseIf (snakeDirection = west) Then
snakeVX = -1
snakeVY = 0
EndIf
snake[1][x] = snake[1][x] + snakeVX
snake[1][y] = snake[1][y] + snakeVY

CheckCollisions()
EndSub

Sub CheckCollisions
' Store head attributes
head = snake[1][segment]
headX = snake[1][x]
headY = snake[1][y]

' Check collision against snakes own body
For iC = 2 To visibleSegments
If (headX = snake[iC][x]) And (headY = snake[iC][y]) Then
Shapes.HideShape(snake[iC][segment])
badCollsion = "True"
EndIf
EndFor

' Check that Snake head has not gone over the boundary
If (headX < 0) Or (headX > gridWidth) Then
badCollsion = "True"
ElseIf (headY < 0) Or (headY > gridHeight) Then
badCollsion = "True"
EndIf

' Check Snake head collision with Food
If (headX = foodX) And (headY = foodY) Then
goodCollision = "True"
EndIf

If (goodCollision) Then
goodCollision = "False"
EatFood()
EndIf

If (badCollsion = "True") Then
GameOver()
EndIf
EndSub

Sub EatFood
MoveFood()
visibleSegments = visibleSegments + 1
score = score + 5
EndSub


Sub GameOver
run = false
badCollsion = "False"
For i = 1 To visibleSegments
Shapes.SetOpacity(snake[i][segment], 40)
EndFor
Shapes.ShowShape(gameOverMessage)
EndSub



Sub MoveFood
GraphicsWindow.BrushColor = GraphicsWindow.BackgroundColor
GraphicsWindow.FillRectangle(foodDrawX, foodDrawY,20,20)
foodX = Math.GetRandomNumber(gridWidth)-1
foodY = Math.GetRandomNumber(gridHeight)-1
DrawFood()
EndSub

Sub DrawFood
foodDrawX = foodX * gridSize
foodDrawY = (foodY * gridSize) + titleRegion
GraphicsWindow.BrushColor = "Crimson"
GraphicsWindow.FillEllipse(foodDrawX,foodDrawY,20,20)
GraphicsWindow.PenColor = "Black"
GraphicsWindow.DrawLine(foodDrawX+10,foodDrawY+5,foodDrawX+7,foodDrawY)
GraphicsWindow.BrushColor = "LawnGreen"
GraphicsWindow.FillEllipse(foodDrawX+10,foodDrawY,10,4)
EndSub



Sub DrawGrid
gridSize = 20
gridWidth = (gw / gridSize) - 1
gridHeight = (gh / gridSize) - 1
offset = gw - (gridWidth * gridSize)

GraphicsWindow.PenWidth = 1
GraphicsWindow.PenColor = "#D0FFFFFF"
'GraphicsWindow.DrawLine(0,titleRegion,gw,titleRegion)
Shapes.AddLine(0,titleRegion,gw,titleRegion)

' draw Grid on game surface to assist development and debugging
'GraphicsWindow.PenColor = "#40FFFFFF"

'For gridY = 1 To gridHeight
' GraphicsWindow.DrawLine(0, (gridY * gridSize)+titleRegion, gw, (gridY * gridSize)+titleRegion)
'EndFor

'For gridX = 1 To gridWidth
' GraphicsWindow.DrawLine(gridX * gridSize, 0+titleRegion, gridX * gridSize, gh+titleRegion)
'EndFor
EndSub


Sub SetupWindow
GraphicsWindow.Width = gw
GraphicsWindow.Height = gh + titleRegion
GraphicsWindow.BackgroundColor = "Black"
GraphicsWindow.Title = "Snake Game V3"
GraphicsWindow.KeyDown = OnKeyDown

Timer.Tick = OnTimerTick

EndSub

Sub SetupGlobals
true = "True"
false = "False"
score = 0
stop = 0
north = 1
east = 2
south = 3
west = 4
resetTime = 4
resetCounter = 0
resetActive = "False"
foodDrawX = -50
foodDrawY = -50

' Game State
run = false

' Variables for adjusting interval time and speeding up game
intervalTime = 250
totalGameTime = 0
adjustmentTime = 10000
minIntervalTime = 50
EndSub

Sub SetupGUI
' Setup shape and label to display the score
GraphicsWindow.BrushColor = "LightBlue"
GraphicsWindow.FontName = "Courier New"
GraphicsWindow.FontSize = 25
GraphicsWindow.DrawText(10,3, "SCORE:")
scoreShape = Shapes.AddText(score)
Shapes.Move(scoreShape, 100, 3)
GraphicsWindow.DrawText(380,3,"Snake Length:")
lengthShape = Shapes.AddText(0)
Shapes.Move(lengthShape, 580,3)

' Shapes to display instructions
Instructions = Shapes.AddText("Move Snake with Arrow Keys")
Shapes.HideShape(Instructions)
GraphicsWindow.BrushColor = "White"
StartMessage = Shapes.AddText("Press Space Bar to Start")
Shapes.HideShape(StartMessage)
Shapes.Move(StartMessage,140, titleRegion+50)
Shapes.Move(Instructions, 130, titleRegion+90)

' Shape to Display GameOver Message
GraphicsWindow.FontSize = 40
gameOverMessage = Shapes.AddText("GAME OVER")
Shapes.HideShape(gameOverMessage)
Shapes.Move(gameOverMessage, 200, titleRegion+200)

' Show Instructions
Shapes.ShowShape(StartMessage)
Shapes.ShowShape(Instructions)
GraphicsWindow.FontSize = 12
EndSub

Sub UpdateGui
Shapes.SetText(scoreShape, score)
Shapes.SetText(lengthShape, visibleSegments)
EndSub

Sub AdjustTimer
' Allow player to eat the first 5 apples then gradually reduce interval time to increase speed
' based on IntervalTime, minIntervalTime, adjustmentTime, totalGameTime
If (score > 25) Then
GameTime = GameTime + intervalTime
If (GameTime > adjustmentTime) And (intervalTime > minIntervalTime) Then
GameTime = 0
intervalTime = intervalTime - 20
If (intervalTime < minIntervalTime) Then
intervalTime = minIntervalTime
EndIf
Timer.Interval = intervalTime
EndIf
EndIf
EndSub



Sub OnTimerTick
GameLoop()
EndSub

Sub OnKeyDown
'TODO: Make the game only recognise one key input per frame
key = GraphicsWindow.LastKey
If (run) Then
If (key = "Up") And (snakeDirection <> south) Then
snakeDirection = north
ElseIf (key = "Right") And (snakeDirection <> west) Then
snakeDirection = east
ElseIf (key = "Down") And (snakeDirection <> north) Then
snakeDirection = south
ElseIf (key = "Left") And (snakeDirection <> east) Then
snakeDirection = west
EndIf
Else
If (key = "Space") Then
run = true
Shapes.HideShape(Instructions)
Shapes.HideShape(StartMessage)
EndIf
EndIf



If (key = "Escape") Then
Program.End()
EndIf
EndSub