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用VB编写DirectX7.0游戏(下)
发表日期:2002-12-08作者:[] 出处:  

  2.3 设置显示模式

  设置显示模式是使用SetDispalyMode函数实现的,函数的定义如下:

   object.SetDisplayMode( _

   w As Long, _

   h As Long, _

   bpp As Long, _

   ref As Long, _

   mode As CONST_DDSDMFLAGS

  其中参数w、h分别指定屏幕的宽度和高度,bpp指定屏幕显示的颜色位数,参数ref指定屏幕的刷新频率,设置为0使用显示驱动的缺省刷新频率,mode指定附加的参数。要获得系统支持的显示模式,可以使用DirectDraw对象的GetDisplayModesEnum函数来遍历所有支持的显示模式。

  2.4 建立平面对象

  一个平面或者说DirectDrawSurface对象是DirectDraw中图形显示和绘制对象。用户可以在DirectDrawSurface上贴位图、绘制图形,还可以直接操作DirectDrawSurface对象使用显存里的内容。利用DirectDraw对象的CreateSurface方法可以建立一个DirectDrawSurface7对象。例如:

  Public DDSFrontDesc As DDSURFACEDESC2

   With DDSFrontDesc

  .lFlags = DDSD_CAPS

  .ddsCaps.lCaps=DDSCAPS_PRIMARYSURFACE '

   End With

  Set DDSFront = DDraw.CreateSurface(DDSFrontDesc)

  也可以利用DirectDraw对象的CreateSurfaceFromFile函数或者CreateSurfaceFromResource函数建立一个DirectDrawSurface7对象,同时将图像文件或者资源文件中的图像装入建立的DirectDrawSurface中。如果上面的函数调用成功,函数将返回一个DirectDrawSurface对象。如果在设定DirectDraw对象的协作层时将其设置为全屏幕模式的话,为了改善图像性能,可以设立一个主平面和若干个屏下缓冲平面,首先在屏下平面中生成图像,然后将图像翻转到主平面上,这样可以有效地避免图像闪烁。

  下面通过一个具体的范例来对DirectDraw进行说明:这个范例建立一个全屏幕的DirectDraw对象,通过操作主显示平面的显示内存在屏幕上显示火焰字的特效,然后按Enter键可以将DirectDraw平面中的图形保存起来。程序的具体实现如下:

  建立一个新的工程文件,点击菜单中的 Project | Reference 选项,打开Object Library 列表窗口,将DirectX 7.0 For Visual Basic Type Library 加入工程文件。将Form1的Name属性改变为MainForm,在MainForm中加入一个PictureBox控件,将其的Visible属性设置为False。然后在MainForm的代码窗口中加入以下代码:

  Private Sub Form_KeyPress(KeyAscii As Integer)

   Dim sRect As RECT

   Dim hdcSrc As Long

   If KeyAscii = 27 Then

   ExitLoop = True

   'End

   ElseIf KeyAscii = vbKeyReturn Then

  DDSFront.BltToDC Picture1.hDC, sRect, sRect

   With Picture1

   '获得与主显示平面兼容的图形设备句柄

   hdcSrc = DDSFront.GetDC

   '保存图像

   Set .Picture = SaveTohBmp(hdcSrc, 0, 0, 640, 480)

   '释放图形句柄

   DDSFront.ReleaseDC hdcSrc

   SavePicture Picture1, “c:\a.bmp”

   End With

   End If

  End Sub

  

  Public Sub Form_Paint()

   BlitRect.Right = DDSBackDesc.lWidth

   BlitRect.Bottom = DDSBackDesc.lHeight

   DDSFront.Blt BlitRect, DDSBack, BlitRect, DDBLT_WAIT

  End Sub

  在工程文件中加入一个Module文件,这个文件中DirectDraw操作做出了定义,在这个Module中加入以下代码:

  Option Explicit

  Public DX As New DirectX7

  Public DDraw As DirectDraw7

  Public DDSFront As DirectDrawSurface7

  Public DDSFrontDesc As DDSURFACEDESC2

  Public DDSBack As DirectDrawSurface7

  Public DDSBackDesc As DDSURFACEDESC2

  Public Clipper As DirectDrawClipper

  Dim Pict() As Byte

  Dim AlphaRect As RECT

  Dim X As Long, Y As Long

  Dim Temp As Long

  Dim Index As Long

  Dim Index2 As Long

  Dim Pos As Long

  Dim PosPlus1 As Long

  Dim PosPlus2 As Long

  Dim PosPlus3 As Long

  Public Pal(255) As PALETTEENTRY

  Public Palette As DirectDrawPalette

  Public BlitRect As RECT

  Public FullSize As Boolean

  Public ExitLoop As Boolean

  Dim Accum As Long

  Dim Msg(9) As String

  Dim Counter As Long

  Dim MsgIndex As Long

  Dim bDrawText As Boolean

  Dim lastTime As Long

  Dim XPos As Long, YPos As Long

  Dim wait As Long

  Dim Angle As Single

  Dim Flag As Boolean

  Dim Count As Long

  Dim CurModeActiveStatus As Boolean

  Dim bRestore As Boolean

  Dim Mode As Boolean

  Private Sub Main()

   InitializeDX

  '初始化Picture1以获得DirectDraw界面图像

   With MainForm.Picture1 .Width = 640 * Screen.TwipsPerPixelX .Height = 480 * Screen.TwipsPerPixelY

   End With

  DDSBack.SetForeColor RGB(255, 255, 255)

   MainForm.Font.Name = “宋体”

   DDSBack.SetFont MainForm.Font

  Msg(0) =“一个显示火焰字的演示”

  Msg(1) =“演示”

  Msg(2) =“利用VB阵列”

  Msg(3) =“对显示内存”

  Msg(4) =“进行直接存取”

  Msg(5) =“{Esc}键退出”

   '设置8位的调色板

   For Index = 0 To 84

   Pal(Index + 1).red = Index * 3 + 3

   Pal(Index + 1).green = 0

   Pal(Index + 1).blue = 0

   Pal(Index + 86).red = 255

   Pal(Index + 86).green = Index * 3 + 3

   Pal(Index + 86).blue = 0

   Pal(Index + 171).red = 255

   Pal(Index + 171).green = 255

   Pal(Index + 171).blue = Index * 3 + 3

   Next

  Set Palette = DDraw.CreatePalette(DDPCAPS_8BIT _ Or DDPCAPS_ALLOW256, Pal())

   DDSFront.SetPalette Palette

  AlphaRect.Right = DDSBackDesc.lWidth - 1

  AlphaRect.Bottom=DDSBackDesc.lHeight- 1

   DDSBack.Lock AlphaRect, DDSBackDesc, DDLOCK_WAIT, 0

  

   DDSBack.GetLockedArray Pict()

   For X = 0 To 639

   For Y = 0 To 479

   Pict(X, Y) = 0

   Next

   Next

   'Corresponding unlock

   DDSBack.Unlock AlphaRect

   While Not ExitLoop

   Mode = ExModeActive

   bRestore = False

   Do Until ExModeActive

   DoEvents

   bRestore = True

   Loop

   DoEvents

   If bRestore Then

   bRestore = False

   DDraw.RestoreAllSurfaces

   End If

   DDSBack.Lock AlphaRect, DDSBackDesc, DDLOCK_WAIT, 0

   DDSBack.GetLockedArray Pict()

   For Y = 0 To 479

   Pict(0, Y) = 0

   Pict(639, Y) = 0

   Next

   For X = 0 To 639

   Pict(X, 477) = Rnd * 220 + 35

   Pict(X, 478) = Rnd * 220 + 35

   Pict(X, 479) = Rnd * 220 + 35

   Next

   Accum = 0

   For X = 1 To 638

   For Y = 0 To 477

   Accum = (Accum + Pict(X, Y + 1) _

   + Pict(X, Y + 2) _

   + Pict(X + 1, Y + 1) _

   + Pict(X - 1, Y + 1)) \ 5

   If Accum < 0 Then

   Accum = 0

   ElseIf Accum > 255 Then

   Accum = 255

   End If

   Pict(X, Y) = Accum

   Next

   Next

   For X = 0 To 639

   Pict(X, 0) = 0

   Pict(X, 1) = 0

   Next

   X = Rnd * 639

   For Y = 50 To 439

   Next

   DDSBack.Unlock AlphaRect

  If DX.TickCount() - lastTime > wait Then

   If Counter = 0 Then

   bDrawText = True

   Counter = 1

   XPos = Rnd * 200

   YPos = 300 + Rnd * 140

   wait = 400

   ElseIf Counter = 1 Then

   MsgIndex = MsgIndex + 1

   If MsgIndex > 5 Then MsgIndex = 0

   bDrawText = False

   Counter = 0

   wait = 2000

   End If

   lastTime = DX.TickCount

   End If

   If bDrawText Then

   On Error Resume Next

   DDSBack.DrawText XPos, YPos, Msg(MsgIndex), False

   On Error GoTo 0

   End If

   MainForm.Form_Paint

   Wend

   TerminateDX

   End

  End Sub

  Function ExModeActive() As Boolean

   Dim TestCoopRes As Long

  TestCoopRes = DDraw.TestCooperativeLevel

   Select Case TestCoopRes

   Case DDERR_NOEXCLUSIVEMODE

   ExModeActive = False

   Case DD_OK

   ExModeActive = True

   End Select

  End Function

  Public Sub InitializeDX()

  MainForm.Left = 0

  MainForm.Top = 0

  MainForm.Height =640 * Screen.TwipsPerPixelY

  MainForm.Width = 480 * Screen.TwipsPerPixelX

  MainForm.Show

   '建立DirectDraw对象

   Set DDraw = DX.DirectDrawCreate(“”)

   '设定DirectDraw对象的协作层

   DDraw.SetCooperativeLevel MainForm.hWnd, DDSCL_EXCLUSIVE Or DDSCL_FULLSCREEN ' DDSCL_NORMAL

   '设定显示模式位640×480×8位颜色

   DDraw.SetDisplayMode 640, 480, 8, 0, DDSDM_DEFAULT

   '设定DDSFrontDesc为主平面

   With DDSFrontDesc

  .lFlags = DDSD_CAPS

  .ddsCaps.lCaps = DDSCAPS_PRIMARYSURFACE 'Or DDSCAPS_SYSTEMMEMORY

   End With

   '设定DDSBackDesc为后台缓冲平面

   With DDSBackDesc

  .ddsCaps.lCaps = DDSCAPS_SYSTEMMEMORY

  .lFlags = DDSD_CAPS Or DDSD_WIDTH Or DDSD_HEIGHT

  .lWidth = 640

  .lHeight = 480

   End With

   '建立平面

   Set DDSFront = DDraw.CreateSurface(DDSFrontDesc)

   Set DDSBack = DDraw.CreateSurface(DDSBackDesc)

   Set Clipper = DDraw.CreateClipper(0)

   Clipper.SetHWnd MainForm.hWnd

   DDSFront.SetClipper Clipper

   DDSBack.SetClipper Clipper

   DoEvents

   Exit Sub

  ERRoUT:

   If Not (DDraw Is Nothing) Then

   DDraw.RestoreDisplayMode

   DDraw.SetCooperativeLevel MainForm.hWnd, DDSCL_NORMAL

   DoEvents

   End If

   MsgBox “无法对DirectDraw进行初始化 ”+Chr(13)+“也许你的显示卡不支持 640×480×8 显示模式 ”

   End

  End Sub

  Public Sub TerminateDX()

   '子程序TerminateDX回复原来的显示模式并且释放所有的DirectDraw有关对象

   DDraw.RestoreDisplayMode

   DDraw.SetCooperativeLevel MainForm.hWnd, DDSCL_NORMAL

   DoEvents

   Set Clipper = Nothing

   Set DDSBack = Nothing

   Set DDSFront = Nothing

   Set DDraw = Nothing

   Set DX = Nothing

  End Sub

  在工程文件中再加入一个Module,这个Module主要定义与图像保存相关的操作,在建立的Module中加入以下代码:

   Option Explicit

  Option Base 0

  Private Type PALETTEENTRY

   peRed As Byte

   peGreen As Byte

   peBlue As Byte

   peFlags As Byte

  End Type

  

  Private Type LOGPALETTE

   palVersion As Integer

   palNumEntries As Integer

   palPalEntry(255) As PALETTEENTRY

  End Type

  

  Private Type GUID

   Data1 As Long

   Data2 As Integer

   Data3 As Integer

   Data4(7) As Byte

  End Type

  Private Const RASTERCAPS As Long = 38

  Private Const RC_PALETTE As Long = &H100

  Private Const SIZEPALETTE As Long = 104

  Private Declare Function CreateCompatibleDC Lib “GDI32” (ByVal hDC As Long) As Long

  Private Declare Function CreateCompatibleBitmap Lib “GDI32” (ByVal hDC As Long, ByVal nWidth As Long, ByVal nHeight As Long) As Long

  Private Declare Function GetDeviceCaps Lib “GDI32” (ByVal hDC As Long, ByVal iCapabilitiy As Long) As Long

  Private Declare Function GetSystemPaletteEntries Lib “GDI32” (ByVal hDC As Long, ByVal wStartIndex As Long, ByVal wNumEntries As Long, lpPaletteEntries As PALETTEENTRY) As Long

  Private Declare Function CreatePalette Lib “GDI32”(lpLogPalette As LOGPALETTE) As Long

  Private Declare Function SelectObject Lib “GDI32”(ByVal hDC As Long, ByVal hObject As Long) As Long

  Private Declare Function BitBlt Lib “GDI32”(ByVal hDCDest As Long, ByVal XDest As Long, ByVal YDest As Long, ByVal nWidth As Long, ByVal nHeight As Long, ByVal hdcSrc As Long, ByVal XSrc As Long, ByVal YSrc As Long, ByVal dwRop As Long) As Long

  Private Declare Function DeleteDC Lib “GDI32”(ByVal hDC As Long) As Long

  Private Declare Function GetForegroundWindow Lib “USER32” () As Long

  Private Declare Function SelectPalette Lib “GDI32”(ByVal hDC As Long, ByVal hPalette As Long, ByVal bForceBackground As Long) As Long

  Private Declare Function RealizePalette Lib “GDI32” (ByVal hDC As Long) As Long

  Private Declare Function GetWindowDC Lib “USER32” (ByVal hWnd As Long) As Long

  Private Declare Function GetDC Lib “USER32"(ByVal hWnd As Long) As Long

  Private Declare Function GetWindowRect Lib “USER32”(ByVal hWnd As Long, lpRect As RECT) As Long

  Private Declare Function ReleaseDC Lib “USER32”(ByVal hWnd As Long, ByVal hDC As Long) As Long

  Private Declare Function GetDesktopWindow Lib “{USER32"() As Long

  

  Private Type PicBmp

   Size As Long

   Type As Long

   hBmp As Long

   hPal As Long

   Reserved As Long

  End Type

  Private Declare Function OleCreatePictureIndirect Lib “olepro32.dll” (PicDesc As PicBmp, RefIID As GUID, ByVal fPictureOwnsHandle As Long, IPic As IPicture) As Long

  

  Public Function SaveTohBmp(ByVal hdcSrc As Long, ByVal LeftSrc As Long, _

   ByVal TopSrc As Long, ByVal WidthSrc As Long, ByVal HeightSrc As Long) As Picture

   Dim hDCMemory As Long

   Dim hBmp As Long

   Dim hBmpPrev As Long

   Dim r As Long

   Dim hPal As Long

   Dim hPalPrev As Long

   Dim RasterCapsScrn As Long

   Dim HasPaletteScrn As Long

   Dim PaletteSizeScrn As Long

   Dim LogPal As LOOGPALETTE

   '建立一个内存图形设备句柄

  hDCMemory=CreateCompatibleDC(hdcSrc)

  '建立一个bitmap并保存到hDCMemory中

  hBmp = CreateCompatibleBitmap(hdcSrc, WidthSrc, HeightSrc)

   hBmpPrev = SelectObject(hDCMemory, hBmp)

   RasterCapsScrn = GetDeviceCaps(hdcSrc, RASTE图CAPS) 'rRaste

   HasPaletteScrn = RasterCapsScrn And RC_PALtTTEic1 ' Palette

   PaletteSizeScrn = GetDeviceCaps(hdcSrc, SIZEPALETTE) ' Size of

   If HasPaletteScrn And (PaletteSizeScrn = 256) Then

   '建立系统调色板的拷贝

   LogPal.palVersion = &H300

   LogPal.palNumEntries = 256

   r = GetSystemPaletteEntries(hdcSrc, 0, 256, LogPal.palPalEntry(0))

   hPal = CreatePalette(LogPal)

   hPalPrev = SelectPalette(hDCMemory, hPal, 0)

   r = RealizePalette(hDCMemory)

   End If

   '将屏幕图形拷贝到内存图形设备句柄中

   r = BitBlt(hDCMemory, 0, 0, WidthSrc, HeightSrc, hdcSrc, LeftSrc, TopSrc, vbSrcCopy)

   hBmp = SelectObject(hDCMemory, hBmpPrev)

   If HasPaletteScrn And (PaletteSizeScrn = 256) Then

   hPal = SelectPalette(hDCMemory, hPalPrev, 0)

   End If

  '释放图形设备句柄

   r = DeleteDC(hDCMemory)

   Debug.Print r

   '调用CreateBitmapPicture函数从指定的bitmap对象和调色板中建立一个picture对象

   Set SaveTohBmp = CreateBitmapPicture(hBmp, hPal)

  End Function

  Public Function CreateBitmapPicture(ByVal hBmp As Long, ByVal hPal As Long) As Picture

   Dim r As Long

   Dim Pic As PicBmp

   Dim IPic As IPicture

   Dim IID_IDispatch As GUID

   '填充IDispatch界面

   With IID_IDispatch

   .Data1 = &H20400

   .Data4(0) = &HC0

   .Data4(7) = &H46

   End With

   '填充Pic结构

   With Pic

   .Size = Len(Pic) ' Length of structure.

   .Type = vbPicTypeBitmap ' Type of Picture (bitmap).

   .hBmp = hBmp ' Handle to bitmap.

   .hPal = hPal ' Handle to palette (may be null).

   End With

   '建立Picture对象

   r = OleCreatePictureIndirect(Pic, IID_IDispatch, 1, IPic)

   '返回Picture对象

   Set CreateBitmapPicture = IPic

  End Function

  运行程序,在屏幕上会出现一些火焰字的特效,按Enter键可以将屏幕保存到“c:\a.bmp”中,按Esc键退出程序回到Windows。

  在上面的程序中,程序首先建立一个DirectDraw对象,然后设置该对象的协作层为全屏协作模式,接下来设置显示模式为640×480×8位颜色,建立一个前台DirectDrawSurface对象和一个后台缓冲DirectDrawSurface对象,建立和设置DirectDrawClipper对象。

  在主程序段中,程序首先对前台绘图平面的调色板(DirectDrawPalette

  )对象进行操作以改变显示的文字的颜色,然后对后台缓冲绘图平面进行字节操作,以产生文字弥散的效果,然后再将后台缓冲绘图平面翻转到前台。当用户按下Enter键之后,程序获得与前台绘图平面相兼容的图形设备句柄,然后再调用Windows API函数将绘图平面内存中的内容保存到Windows位图文件中。

  上面粗略地介绍了DirectX7 SDK的新特性以及初步的DirectDraw编程,希望对大家能有所帮助。以上的程序在Windows98、VB6.0下运行通过。

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