Full Screen GUI Development

Pt 1 ?The Basics

By Jim (Machaira) Perry

In this article we抣l look at developing a GUI for full-screen DirectX games. The code accompanying this article may be used as a base for developing your own GUI class. It will necessarily be simplistic, but may give you an idea of how to go about writing your own GUI code.

This article assumes a working knowledge of DirectX 7 and VB classes.

Download this tutorial (in Word format) and the sample projects in a zip file (336 KB)

When you think of a GUI you think in terms of windows, so the base class will handle most normal window properties and draw the bitmap used to represent the window. A bitmap for a simple window could look like the following.

This window has no Control Box or minimize, maximize, and close buttons. It抯 about as simple as you can get. See the window.bmp file.

Several example of more complex GUI抯 are below:

Figure 1 - Quake III Arena GUI

Figure 2 - Unreal Tournament GUI

Our GUI class won抰 quite be up to the task of handling something like this, but it抣l eventually be pretty useful.

Below is a first try at a base window class (see the WindowSample1 project):

ClsWindow Class

Option Explicit

Private objBitmap As DirectDrawSurface7

Private iX As Integer

Private iY As Integer

Private iWidth As Integer

Private iHeight As Integer

''''Center the window against the parent window

''''For a base window the parent is the screen

Private bCenterX As Boolean

Private bCenterY As Boolean

''''Used for centering purposes

Private iParentWidth As Integer

Private iParentHeight As Integer

Private iParentX As Integer

Private iParentY As Integer

Public Property Let X(ByVal iData As Integer)

    iX = iData

End Property

Public Property Get X() As Integer

    X = iX

End Property

Public Property Let Y(ByVal iData As Integer)

    iY = iData

End Property

Public Property Get Y() As Integer

    Y = iY

End Property

''''Only Property Get for Width and Height properties

''''since they are set by the dimensions of the bitmap

Public Property Get Width() As Integer

    Width = iWidth

End Property

Public Property Get Height() As Integer

    Height = iHeight

End Property

Public Property Let CenterX(ByVal bData As Boolean)

    bCenterX = bData

    iX = ((iParentWidth / 2) + iParentX) - (iWidth / 2)

End Property

Public Property Get CenterX() As Boolean

    CenterX = bCenterX

End Property

Public Property Let CenterY(ByVal bData As Boolean)

    bCenterY = bData

    iY = ((iParentHeight / 2) + iParentY) - (iHeight / 2)

End Property

Public Property Get CenterY() As Boolean

    CenterY = bCenterY

End Property

Public Property Let ParentWidth(ByVal iData As Integer)

    iParentWidth = iData

End Property

Public Property Get ParentWidth() As Integer

    ParentWidth = iParentWidth

End Property

Public Property Let ParentHeight(ByVal iData As Integer)

    iParentHeight = iData

End Property

Public Property Get ParentHeight() As Integer

    ParentHeight = iParentHeight

End Property

Public Property Let ParentX(ByVal iData As Integer)

    iParentX = iData

End Property

Public Property Get ParentX() As Integer

    ParentX = iParentX

End Property

Public Property Let ParentY(ByVal iData As Integer)

    iParentY = iData

End Property

Public Property Get ParentY() As Integer

    ParentY = iParentY

End Property

Public Property Let ObjectSurface(ByVal objSurface As DirectDrawSurface7)

    Dim ddsd As DDSURFACEDESC2

    Set objBitmap = objSurface

    objBitmap.GetSurfaceDesc ddsd

    iHeight = ddsd.lHeight

    iWidth = ddsd.lWidth

End Property

Public Function DrawObject(objSurface As DirectDrawSurface7)

    Dim rectObject As RECT

    Dim rectBitmap As RECT

    On Error GoTo DrawObjectErr

    rectBitmap.Left = iX

    rectBitmap.Right = iX + iWidth

    rectBitmap.Top = iY

    rectBitmap.Bottom = iY + iHeight

    objSurface.Blt rectBitmap, objBitmap, rectObject, DDBLT_WAIT

    Exit Function

DrawObjectErr:

    Exit Function

End Function

Take a look at the InitDD function in the modDirectDraw module. The following code creates the window object:

    Window.ObjectSurface = objDD.CreateSurfaceFromFile(App.Path & "\window.bmp", ddsdSurf2)

    Window.ParentX = 0

    Window.ParentY = 0

    Window.ParentHeight = 600

    Window.ParentWidth = 800

    Window.CenterX = True

    Window.CenterY = True

This will simply draw a bitmap of a window centered on the screen. It doesn抰 handle input and contains no controls. Although this is a good start it doesn抰 really offer us much.

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