Microsoft Small Basic

Program Listing: QFL408

List Program

' Asteroids Game
' Copyright (C) 2009, Jason T. Jacques
' License: MIT license http://www.opensource.org/licenses/mit-license.php

' Game area controls
gameWidth = 640
gameHeight = 480
backColor = "black"

' Window title
gameTitle = "Asteroids, Score: "

' Target frames per second
fps = 25

' Key controls
leftKey = "Left"
rightKey = "Right"
forwardKey = "Up"
backKey = "Down"
fireKey = "Space"
pauseKey = "P"

' Asteroid (rock) settings
rockSpeed = 1
rockColor = "white"
rockMin = 20 ' small size rock
rockTypes = 3 ' number of rock sizes (multiples of small rock size)
initRocks = 5

' Ammo settings
ammoSpeed = 5
ammoColor = "white"
ammoLife = 60 ' moves before auto destruct
ammoMax = 10
ammoSize = 5

' Player settings
playerColor = "white"
playerHeight = 30
playerWidth = 20
safeTime = 100 ' time player has to get out of the way on level up

' Point multiplier
pointsMultiply = 10

' Array name initialisation
rock = "rockArray"
rockAngle = "rockAngle"
rockSize = "rockSize"
ammo = "ammoArray"
ammoAngle = "ammoAngle"
ammoAge = "ammoAge"


' Start game
Init()
Play()


' Setup world
Sub Init
GraphicsWindow.Hide()
GraphicsWindow.Title = gameTitle + "0"
GraphicsWindow.CanResize = false
GraphicsWindow.Width = gameWidth
GraphicsWindow.Height = gameHeight
GraphicsWindow.BackgroundColor = backColor
GraphicsWindow.BrushColor = backColor

LevelCheck()

GraphicsWindow.PenColor = playerColor
player = Shapes.AddTriangle(playerWidth/2, 0, 0, playerHeight, playerWidth, playerHeight)
Shapes.Move(player, (gameWidth - playerWidth) / 2, (gameHeight - playerHeight) / 2)
playerAngle = 0
EndSub

' Main gane routine
Sub Play
GraphicsWindow.Show()
GraphicsWindow.KeyDown = ChangeDirection

' Main loop
play = 1
pause = 0
While(play = 1)
Program.Delay(1000/fps)
If (pause = 0) Then
Move()
CollisionCheck()
AgeAmmo()
LevelCheck()
EndIf
EndWhile
EndSub

' Read key event and act
Sub ChangeDirection
If(GraphicsWindow.LastKey = rightKey) Then
playerAngle = Math.Remainder(playerAngle + 10, 360)
ElseIf(GraphicsWindow.LastKey = leftKey) Then
playerAngle = Math.Remainder(playerAngle - 10, 360)
ElseIf(GraphicsWindow.LastKey = forwardKey) Then
playerSpeed = playerSpeed + 1
ElseIf(GraphicsWindow.LastKey = backKey) Then
playerSpeed = playerSpeed - 1
ElseIf(GraphicsWindow.LastKey = fireKey) Then
Fire()
ElseIf(GraphicsWindow.LastKey = pauseKey) Then
pause = Math.Remainder(pause + 1, 2)
EndIf
Shapes.Rotate(player, playerAngle)
EndSub

' Move all on screen items
Sub Move
' Move player
x = Math.Remainder(Shapes.GetLeft(player) + (Math.Cos(Math.GetRadians(playerAngle - 90)) * playerSpeed) + gameWidth, gameWidth)
y = Math.Remainder(Shapes.GetTop(player) + (Math.Sin(Math.GetRadians(playerAngle - 90)) * playerSpeed) + gameHeight, gameHeight)
Shapes.Move(player, x, y)

' Move rocks
For i = 1 To Array.GetItemCount(rock)
x = Math.Remainder(Shapes.GetLeft(Array.GetValue(rock, i)) + (Math.Cos(Math.GetRadians(Array.GetValue(rockAngle, i) - 90)) * rockSpeed) + gameWidth, gameWidth)
y = Math.Remainder(Shapes.GetTop(Array.GetValue(rock, i)) + (Math.Sin(Math.GetRadians(Array.GetValue(rockAngle, i) - 90)) * rockSpeed) + gameHeight, gameHeight)
Shapes.Move(Array.GetValue(rock, i), x, y)
EndFor

' Move ammo
For i = 1 To Array.GetItemCount(ammo)
x = Math.Remainder(Shapes.GetLeft(Array.GetValue(ammo, i)) + (Math.Cos(Math.GetRadians(Array.GetValue(ammoAngle, i) - 90)) * ammoSpeed) + gameWidth, gameWidth)
y = Math.Remainder(Shapes.GetTop(Array.GetValue(ammo, i)) + (Math.Sin(Math.GetRadians(Array.GetValue(ammoAngle, i) - 90)) * ammoSpeed) + gameHeight, gameHeight)
Shapes.Move(Array.GetValue(ammo, i), x, y)
Array.SetValue(ammoAge, i, Array.GetValue(ammoAge, i) + 1)
EndFor
EndSub

' Check for collisions between onscreen items
Sub CollisionCheck
' Calculate player bounding box.
px1 = Shapes.GetLeft(player) - ( (Math.Abs(playerWidth * Math.Cos(Math.GetRadians(playerAngle)) + playerHeight * Math.Sin(Math.GetRadians(playerAngle))) - playerWidth) / 2)
py1 = Shapes.GetTop(player) - ( (Math.Abs(playerWidth * Math.Sin(Math.GetRadians(playerAngle)) + playerHeight * Math.Cos(Math.GetRadians(playerAngle))) - playerHeight) / 2)
px2 = px1 + Math.Abs(playerWidth * Math.Cos(Math.GetRadians(playerAngle)) + playerHeight * Math.Sin(Math.GetRadians(playerAngle)))
py2 = py1 + Math.Abs(playerWidth * Math.Sin(Math.GetRadians(playerAngle)) + playerHeight * Math.Cos(Math.GetRadians(playerAngle)))

' Re-order co-oridinates if they are the wrong way arround
If(px1 > px2) Then
tmp = px1
px1 = px2
px2 = tmp
EndIf
If(py1 > py2) Then
tmp = py1
py1 = py2
py2 = tmp
EndIf

' Check if each rock has hit something
For i = 1 To Array.GetItemCount(rock)
ax1 = Shapes.Getleft(Array.GetValue(rock, i))
ay1 = Shapes.GetTop(Array.GetValue(rock, i))
ax2 = ax1 + Array.GetValue(rockSize, i)
ay2 = ay1 + Array.GetValue(rockSize, i)


' Player collison
If(playerSafe < 1) Then
If ( (ax1 < px1 And ax2 > px1) Or (ax1 < px2 And ax2 > px2) ) Then
If ( (ay1 < py1 And ay2 > py1) Or (ay1 < py2 And ay2 > py2) ) Then
EndGame()
EndIf
EndIf
EndIf


' Ammo collison
For j = 1 to Array.GetItemCount(ammo)
bx1 = Shapes.Getleft(Array.GetValue(ammo, j))
by1 = Shapes.GetTop(Array.GetValue(ammo, j))
bx2 = bx1 + ammoSize
by2 = by1 + ammoSize

If ( (ax1 < bx1 And ax2 > bx1) Or (ax1 < bx2 And ax2 > bx2) ) Then
If ( (ay1 < by1 And ay2 > by1) Or (ay1 < by2 And ay2 > by2) ) Then
nextRemove = i
RemoveRock()
nextRemove = j
RemoveAmmo()
EndIf
EndIf
EndFor

EndFor

' Decrease the time player is safe
If (playerSafe > 0) Then
playerSafe = playerSafe - 1
EndIf
EndSub


' Add a new rock to the world
Sub AddRock
' Check if the next rock size/position has been specified
If (nextSize <> 0) Then
size = rockMin* nextSize
x = Shapes.GetLeft(nextPosition)
y = Shapes.GetTop(nextPosition)
nextSize = 0
Else
' Choose a random size and position
size = rockMin * Math.GetRandomNumber(rockTypes)
x = Math.GetRandomNumber(gameWidth - size)
y = Math.GetRandomNumber(gameHeight - size)
EndIf

' Draw the rock
GraphicsWindow.PenColor = rockColor
Array.SetValue(rock, (Array.GetItemCount(rock) + 1), Shapes.AddEllipse(size, size))
Shapes.Move(Array.GetValue(rock, Array.GetItemCount(rock)), x, y)
Array.SetValue(rockAngle, Array.GetItemCount(rock), Math.GetRandomNumber(360))
Array.SetValue(rockSize, Array.GetItemCount(rock), size)
EndSub

' Remove a rock from the world and update score
Sub RemoveRock
removeSize = Array.GetValue(rockSize, nextRemove) / rockMin
' If not a mini rock
If (removeSize > 1) Then
' ... add new rocks until we have made up for it being broken apart...
While(removeSize > 0)
nextSize = Math.GetRandomNumber(removeSize - 1)
nextPosition = Array.GetValue(rock, nextRemove)
removeSize = removeSize - nextSize
AddRock()
EndWhile
' And give a point for a 'hit'
score = score + 1
Else
' We've destroyed it - give some extra points and
score = score + 5
EndIf

' Show updated score
GraphicsWindow.Title = gameTitle + (score * pointsMultiply)

' Remove all references from the arrays
Shapes.Remove(Array.GetValue(rock, nextRemove))
For i = nextRemove To (Array.GetItemCount(rock) - 1)
Array.SetValue(rock, i, Array.GetValue(rock, i+1))
Array.SetValue(rockAngle, i, Array.GetValue(rockAngle, i+1))
Array.SetValue(rockSize, i, Array.GetValue(rockSize, i+1))
EndFor
Array.RemoveValue(rock, Array.GetItemCount(rock))
Array.RemoveValue(rockAngle, Array.GetItemCount(rockAngle))
Array.RemoveValue(rockSize, Array.GetItemCount(rockSize))
EndSub

' Check if the player has completed the level, if so, level up
Sub LevelCheck
If(Array.GetItemCount(rock) < 1) Then
nextSize = 0
For i = 1 To initRocks
AddRock()
EndFor
initRocks = initRocks + 1

' Give players some time to move out of the way
playerSafe = safeTime
EndIf
EndSub

' Add ammo to game
Sub Fire
' Remove additional ammo
While(Array.GetItemCount(ammo) > (ammoMax - 1))
nextRemove = 1
RemoveAmmo()
EndWhile

' Add the ammo
GraphicsWindow.PenColor = ammoColor
Array.SetValue(ammo, (Array.GetItemCount(ammo) + 1), Shapes.AddEllipse(ammoSize, ammoSize))
Shapes.Move(Array.GetValue(ammo, Array.GetItemCount(ammo)), (px1 + px2 - ammoSize) / 2, (py1 + py2 - ammoSize) / 2)
Array.SetValue(ammoAngle, Array.GetItemCount(ammo), playerAngle)
EndSub

' Check ammo age
Sub AgeAmmo
While (Array.GetValue(ammoAge, 1) > ammoLife)
nextRemove = 1
RemoveAmmo()
EndWhile
EndSub

' Remove top Ammo
Sub RemoveAmmo
Shapes.Remove(Array.GetValue(ammo, nextRemove))
For i = nextRemove To (Array.GetItemCount(ammo) - 1)
Array.SetValue(ammo, i, Array.GetValue(ammo, i+1))
Array.SetValue(ammoAngle, i, Array.GetValue(ammoAngle, i+1))
Array.SetValue(ammoAge, i, Array.GetValue(ammoAge, i+1))
EndFor
Array.RemoveValue(ammo, Array.GetItemCount(ammo))
Array.RemoveValue(ammoAngle, Array.GetItemCount(ammoAngle))
Array.RemoveValue(ammoAge, Array.GetItemCount(ammoAge))
EndSub

' Display simple end game message box
Sub EndGame
play = 0
Shapes.Remove(player)
GraphicsWindow.ShowMessage("You scored " + (score * pointsMultiply) + " points. Thanks for Playing.", "Game Over!")
EndSub