Following object

[AlmarM]

Hi!

Im currently learning how to make a Tower Defence game at my school. They shown us how to make something 'follow' something.

So I wrote a little example, mayby useful for other.

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#include <Math.au3>

Global $_Timer
Global $fX = 10, $fY = 10
Global $tX = 400, $tY = 570

$GUI = GUICreate("ATan2", 800, 600)
$Follower = GUICtrlCreateLabel("", $fX, $fY, 20, 20)
GUICtrlSetBkColor($Follower, 0x00FF00)
$Target = GUICtrlCreateLabel("", $tX, $tY, 20, 20)
GUICtrlSetBkColor($Target, 0xFF0000)
$Label = GUICtrlCreateLabel("", 10, 10, 150, 20)

$_Timer = TimerInit()

GUISetState()
While 1
    Switch GUIGetMsg()
        Case -3
            Exit
    EndSwitch

    $xDist = $tX - $fX
    $yDist = $tY - $fY
    $Angle = _ATan2($yDist, $xDist)
    $xSpeed = Cos($Angle) * 3
    $ySpeed = Sin($Angle) * 3
    $fX += Round($xSpeed, 0)
    $fY += Round($ySpeed, 0)
    GUICtrlSetPos($Follower, $fX, $fY)

    Sleep(20)

    If ($fX >= $tX - 10 And $fX <= $tX + 19) Then
        GUICtrlSetData($Label, "Status: Hit!")
    Else
        GUICtrlSetData($Label, "Status: Following...")
    EndIf

    If (TimerDiff($_Timer) >= 2000) Then
        Teleport($Target, Random(10, 770), Random(10, 570))
        $_Timer = TimerInit()
    EndIf
WEnd

Func Teleport($cObj, $iX, $iY)
    GUICtrlSetPos($cObj, $iX, $iY)
    $tX = $iX
    $tY = $iY
EndFunc

EDIT:

Another example:

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#include <GUIConstantsEx.au3>
#include <Math.au3>

Global $Radius = 200
Global $hGraphic
Global $eX = 30, $eY = 350, $Speed = 4
Global $Bullet, $BulletX = 230 + 13, $BulletY = 200 + 13
Global $xSpeed, $ySpeed

$GUI = GUICreate("", 500, 430)
$Tower = GUICtrlCreateLabel("", 230, 200, 30, 30)
GUICtrlSetBkColor($Tower, 0xFF0000)

$Enemy = GUICtrlCreateLabel("", 30, 350, 10, 10)
GUICtrlSetBkColor($Enemy, 0x00FF00)

$hGraphic = GUICtrlCreateGraphic(230 + 15, 200 + 15, $Radius, $Radius)
GUICtrlSetGraphic($hGraphic, $GUI_GR_PIE, 0, 0, $Radius, 0, 360)
GUICtrlSetGraphic($hGraphic, $GUI_GR_REFRESH)
GUICtrlSetGraphic($hGraphic, $GUI_GR_CLOSE)

$Bullet = GUICtrlCreateLabel("", $BulletX, $BulletY, 5, 5)
GUICtrlSetBkColor($Bullet, 0x0000FF)

GUISetState()
While 1
    Switch GUIGetMsg()
        Case -3
            Exit
    EndSwitch

    $Pos = WinGetPos($GUI)
    $eX = MouseGetPos(0) - $Pos[0] - 7
    $eY = MouseGetPos(1) - $Pos[1] - 27

    GUICtrlSetPos($Enemy, $eX, $ey)

    If (IsInRange($eX, $eY)) Then
        MoveBullet()
    Else
        $BulletX += $xSpeed
        $BulletY += $ySpeed

        GUICtrlSetPos($Bullet, $BulletX, $BulletY)
    EndIf

    If ($BulletX > 500 Or $BulletX < 0 Or $BulletY < 0 Or $BulletY > 500) Then
        Reset()
    EndIf

    Sleep(20)
WEnd

Func IsInRange($iX, $iY)
    $xDiff = 230 - $iX
    $yDiff = 200 - $iY
    $Distance = Sqrt(($xDiff * $xDiff) + ($yDiff * $yDiff))

    If ($Distance < $Radius) Then
        Return True
    Else
        Return False
    EndIf
EndFunc

Func Reset()
    GUICtrlSetPos($Bullet, 230 + 13, 200 + 13)
    $BulletX = 230 + 13
    $BulletY = 200 + 13
    $xSpeed = 0
    $ySpeed = 0
EndFunc

Func MoveBullet()
    $xDist = $eX - $BulletX
    $yDist = $eY - $BulletY
    $Angle = _ATan2($yDist, $xDist)
    $xSpeed = Cos($Angle) * 4
    $ySpeed = Sin($Angle) * 4
    $BulletX += $xSpeed
    $BulletY += $ySpeed

    GUICtrlSetPos($Bullet, $BulletX, $BulletY)
EndFunc

Edited April 21, 2010 by AlmarM

[Herb191]

Thanks just what I was looking for.