;-------------------------------------------------------------------------------

; Trigonometry: return horizontal vector
Function VectorX# ( Distance# , Angle# )
    Return Sin ( Angle ) * Distance
End Function

; Trigonometry: return vertical vector
Function VectorY# ( Distance# , Angle# )
    Return Sin ( Angle - 90 ) * Distance
End Function

; Trigonometry: return distance using vector
Function VectorDistance# ( X# , Y# )
    Return Sqr ( X * X + Y * Y )
End Function

; Trigonometry: return angle using vector
Function VectorAngle# ( X# , Y# )
    Return 180 - ATan2 ( X , Y )
End Function

;-------------------------------------------------------------------------------

; Blitz graphics window mode states
Const WindowMode_AutoDetect = 0
Const WindowMode_FullScreen = 1
Const WindowMode_Windowed   = 2
Const WindowMode_Scaled     = 3

; Desired screen settings
Const ScreenWidth  = 640
Const ScreenHeight = 480
Const ColorDepth   = 0
Const WindowMode   = WindowMode_AutoDetect

; Bullet control
Const KeySpace =  57
; Game control
Const KeyEsc   =   1

;-------------------------------------------------------------------------------

; Bullet spawning distance from player image hotspot in pixels
Const BulletDistance =   24

; Bullet time to live in milliseconds
Const BulletTime = 5000

; Bullet velocity in pixels
Const BulletSpeed    =    4

; Ship is pointing upwards
Const ShipAngle = 0

;-------------------------------------------------------------------------------

Type Bullet

    ; Time of creation
    Field TimeCreated
    ; Duration of life
    Field TimeToLive

    ; Position
    Field PosX#
    Field PosY#
    ; Velocity
    Field VelX#
    Field VelY#

End Type

;-------------------------------------------------------------------------------

; Smart timing wrapper
Global MilliSecs

; Simple bullet image
Global BulletImage

;-------------------------------------------------------------------------------

Function CreateBullet ( PosX , PosY , VelX# , VelY# )
    Local This.Bullet

    This = New Bullet
    This\PosX = PosX
    This\PosY = PosY
    This\VelX = VelX
    This\VelY = VelY

    This\TimeCreated = MilliSecs

    ; Use default time to live
    This\TimeToLive = BulletTime

End Function


Function UpdateBullets ()
    Local This.Bullet

    For This = Each Bullet

        ; Update position
        This\PosX = This\PosX + This\VelX
        This\PosY = This\PosY + This\VelY

        ; Time to die
        If MilliSecs - This\TimeCreated >= This\TimeToLive
            Delete This
        End If

    Next

End Function


Function DrawBullets ()
    Local This.Bullet

    For This = Each Bullet
        DrawImage BulletImage , This\PosX , This\PosY
    Next

End Function

;-----------------------------------------------------------------------

; Original ship image (pointing upwards)
Local ShipImage

; Bullet starting position & speed vector
Local BulletPosX
Local BulletPosY
Local BulletVelX#
Local BulletVelY#

; Ship position
Local ShipPosX
Local ShipPosY

;-------------------------------------------------------------------------------

; Setup screen
Graphics ScreenWidth , ScreenHeight , ColorDepth , WindowMode
SetBuffer BackBuffer ()

; Load bullet image
BulletImage = LoadImage ( "Bullet.BMP" )
MidHandle BulletImage

; Load and center ship image
ShipImage = LoadImage ( "Ship Pre Final.PNG" )
MidHandle ShipImage

; Place ship in the lower half in the center of the screen
ShipPosX = ScreenWidth  / 2
ShipPosY = ScreenHeight * 3 / 4

Repeat

    ; Timing
    
    MilliSecs = MilliSecs ()

    ; Input

    If KeyDown ( KeySpace )
        ; Calculate where to create bullet in front of ship
        BulletPosX = ShipPosX + VectorX ( BulletDistance , ShipAngle )
        BulletPosY = ShipPosY + VectorY ( BulletDistance , ShipAngle )

        ; Initial bullet velocity vector
        BulletVelX = VectorX ( BulletSpeed , ShipAngle )
        BulletVelY = VectorY ( BulletSpeed , ShipAngle )

        CreateBullet BulletPosX , BulletPosY , BulletVelX , BulletVelY
    EndIf

    ; Update

    UpdateBullets

    ; Render

    Cls

    DrawImage ShipImage , ShipPosX , ShipPosY
    DrawBullets

    Flip

Until KeyHit( KeyEsc )

; Blitz automagically cleans up
End


;~IDEal Editor Parameters:
;~C#Blitz3D198