By Simon Price

Visit www.VBgames.co.uk
for more!

What you will learn

• How to use the DirectX libraries from Visual Basic


• How to get input from the most commonly used devices - keyboard and mouse
    - using DirectInput


• How to load and play a wave file using DirectSound


• How to create a rendering device with Direct3D


• How to use the D3DX helper functions


• How to use vertex and index buffers to create simple geometry


• How to use view and projection matrices to set up a camera


• How to use world matrices to make animation and reuse the same geometry


• How to load textures from a bitmap file


• How to unload all of this safely

How you will learn it

• Overview of DirectX8


• Explanation of DirectX terms


• Explanation of sample program


• Full working demo program to download
    with source code and comments


• Evaluation of what has been learnt


• Exercises to extend your knowledge


• Thoughts for future tutorials

Boring Intro

Back by popular demand is my DirectX tutorial series! Although I'm sort of starting
again for DirectX 8. So for complete newbies, this tutorial is great, and for
those who already know some DX7 or DX8, the tutorial includes some more complex
stuff than previous tutorials. In DirectX 8, the API has become simpler in
the initialization of objects and it also has many more maths functions to help
you. But it's still alot of work to do by yourself, so that's why you should
help spread the word by making free source demos and tutorials. At this point I acknowledge
Richard Hayden for his free source Direct3D8 world, it is a great example of
what I am talking about and helped me begin to learn the new API. Enough of the
chit chat...

Before you begin

If you don't already have DirectX 8 and the DirectX 8 Type Libraries for
Visual Basic then you've got some downloading to do! Sorry, but it is worth it.
You don't need all the SDK documentation, although I recommend getting it, and
you don't need the C++ SDK if you are a VB'er only, so your download might not
be as big as mine was. I managed to download 135 MB though my cheap 56 K phone
line though, and that was the full download including everything. So it is
possible, but you will need to get a program such as GetRight
to help you download such a big file. All developer information and downloads
can be found at www.microsoft.com/directx
. Once DirectX 8 is installed, and you have the DX VB Type Libs, read on.

Adding a reference to your project

Every time you start a new project that will use DirectX, you will need to do
the following:

• Click the Project menu


• Choose the References... submenu and the References dialog will pop up


• Scroll down the list of references until you find the "DirectX 8 Type
    Library for Visual Basic" and check the box next to it


• Click OK

Now VB will know every class, type and enumeration that DirectX 8 contains,
so you're ready to begin coding!

DirectX and 3D terminology

This is the part which gets most people. I wish I had someone to explain all
the jargon to me when I was learning. After the language barrier, things get a
bit easier. Here's some terms you need to know. If you already know a bit about
DirectX, you should probably skip this whole section and only come back to it
when you see a word you don't understand. It is not in alphabetical order,
rather it is in logical order so that you can read the whole thing if you're new
and you want to. As you can see, there is alot of it, and this is only the basics.

• DirectX, DirectAudio (DirectSound, DirectMusic), DirectGraphics
    (Direct3D, DirectDraw), DirectPlay, DirectSetup - These are all part of
    the DirectX API. They are the main objects which deal with different jobs
    e.g DirectAudio takes care of all audio input and output, and it contains
    DirectSound and DirectMusic


• API - What does that stand for again? I think it was Advanced
    Programming Interface (correct me please if I'm wrong). At least I know what
    it means. It's the bunch of objects that give you a higher level view of a
    task, so you don't need to think about writing low level code anymore
    because people have already made functions to do that for you.


• Variable - If you don't know what a variable is, go away and learn
    something simpler.


• Type - I hope you know this too. It's several variables group
    together, in C++ it's a structure.


• Class - This is code that describes an object (see below).


• Object - An object can contain variables like a type, but it also
    can have functions that can be called from code elsewhere. An object is
    created from a class.


• Instance - When an object is created from a class, it is said to be
    an instance of the object. Note there can be many instances of an object
    created from the same class.


• Library - A whole group of objects are often grouped together into
    one file, usually a DLL (Dynamic Link Library). DirectX is made of DLL's.


• Pointer - This is a variable that stores a memory address. In VB,
    your don't use pointers directly, but if you use a object without creating a
    new instance of the object, you are basically using a pointer to another
    object.


• Buffer - A word given to a chunk of memory which has been assigned
    a job, usually to temporarily store data which is moved around alot. There
    are several types of buffer in DirectX.


• Backbuffer, Frontbuffer, Surface, Texture - These are used to store
    graphics. The only visible graphics buffer is the front buffer. In DirectX
    8, you never need to worry about this, just know what it is (erm, like, it's
    what you see on the screen). A back buffer is where graphics go just before
    the front buffer. You draw on the back buffer, and when your super duper
    graphics are finished, you ask DirectX to move it to the front buffer. A
    surface is just like a back buffer, it stores pictures, but it is more
    general since it has nothing to do with a front buffer. A texture is a
    surface used for texture mapping polygons (see later), and is usually of dimensions
    that are square, a power of 2, typically 256 x 256.


• Copy, VSync, Blt, Flip, Discard - These are methods of copying from
    one surface to another. Copying involves copying every single bit from on
    surface to another. Flipping involves moving a pointer to s surface so that
    the front buffer and back buffer surfaces switch roles (their pointers are
    swapped) making for a very quick appearance of a new image. VSync means synchronizing
    the copying or flipping of surfaces with the vertical refresh of the monitor
    so that you can't see the graphics flicker. If you discard your surface when
    you flip, it is a faster, but the contents of the back buffer are not
    guaranteed to be still the same as before the flip.


• Z buffer - A piece of memory that store the z positions of objects
    drawn onto a surface.


• Sound buffers (primary and secondary) - A sound buffer stores a
    sound. A primary sound buffer can be heard out of the speakers, with DirectX
    you can ignore it because it is managed for you. A secondary sound buffer is
    where sounds can be stored before being mixed and sent to the primary
    buffer.


• Mixing - The process of creating just one sound from several source
    sounds.


• Static and streaming - A static buffer stores just a whole sound
    and just sits there. A streaming buffer stores only part of the sound and
    constantly is moving in the next part of the sound and and moving out the
    already played sound. A static buffer is more CPU efficient and a streaming
    buffer is more memory efficient.


• Input device - This is commonly a mouse or a keyboard, but can also
    be a joy pad or a steering wheel etc.


• Device state - The state of the input device depends on what
    buttons/rollers/wheels are being pressed/moved etc. For example, the state
    of the keyboard is that the "X" key is down.


• Rendering device - This is something that draws graphics, it can be
    a hardware graphics card or a software emulation device.


• Hardware and software emulation - Hardware is a physical unit on
    your computer and is usually very fast at doing it's job. Software emulation
    can do the same job as hardware, but at a slower rate and using up memory.


• System and video memory - System memory is the main memory where everything
    else is stored - programs, Windows, anything and everything scattered
    everywhere so it can be slow. Video memory is separately used for hardware
    to store pictures and is usually alot faster. It can be a slow operation to
    copy between these two types of memory.


• Polygon, Primitive - Polygons are a general term for shapes that
    can be made with a number of straight edged sides and are used in 3D store
    create shapes. In Direct3D, a primitive is usually a point, a line or a
    triangle.


• Material - A polygon appears to be made of a material, in DirectX,
    a material has several colors to describe it's appearance.


• Texture mapping - When a polygon has a picture put onto it it is
    said that the polygon has been texture mapped.


• Texture management - Textures must be ordered and and moved around
    so that the right textures are available when they are need. DirectX by
    default can do this for you.


• Vector - A 3 dimensional value, having x, y and z components.


• Vertex - A primitive is made up of vertices (plural of vertex)
    where edges end or meet. They can be just the same as vectors, or they can
    have additional components such as color, direction (or normal), or texture
    coordinates.


• Plane - A flat shape that goes on forever and splits space into 2.
    For example, the ground is a horizontal plane.


• Normal - A normal to a plane or vertex or primitive is a vector
    that describes where it is facing. Has a similar meaning as perpendicular or
    orthogonal.


• Transformation - A formula that changes a vector to another
    position.


• Matrix - Matrices (plural of matrix) describes any transformation
    by storing 16 numbers.


• Translation, rotation, scaling - These are types of
    transformations. A translation is a movement in the x, y or z direction (or
    2 or all 3 directions), a rotation spins the vector around an origin,
    scaling resizes the vector around a origin.


• Origin - A point or vector that is the center of something.


• World, View and Projection - The world transformation affects every
    vector in the world, moving it moves everything. The view transformation
    makes the camera or eye on the scene appear to be in the right place, and
    the projection transformation describes how the 3D scene is conveyed onto
    the 2D picture produced from it.


• Culling - When a polygon is not facing the camera, the process of
    culling ensures it is not drawn.


• Z buffering and Z sorting - This process makes sure that when a
    object is obscured by another, it cannot be seen.


• More... I've missed out loads so if you still don't understand a
    word then just ask.

The sample program

You can download the sample program from here.
You will need a program like Winzip to
decompress it. It is written in Visual Basic 6, if you have another version of
VB then there is information on www.planet-source-code.com/vb
as to how to try to open the version 6 files.

The sample program uses hardware accelerated rasterization. If your computer does not have this, the request
will fail, so use D3DDEVTYPE_REF instead of D3DDEVTYPE_HAL if this happens. A real
program would be able to detect an error and automatically switch device. It also requests software vertex processing, which means the CPU has to
transform and light geometry, but if you have a good graphics card, you might be
able to use hardware vertex processing. 

The sample program assumes your computer can render in 16 bit (R5G6B5) color
format, in 640 x 480 resolution. If this is not the case, it may fail but you
can change those values in the source code.

The sample program renders the same texture mapped 3D cube in different
positions. It uses the same cube but it makes it appear that there are 3, each
of different sizes, and they are all spinning and rotating around everywhere.
The camera can be zoomed in and out using the mouse and the program can be
exited using the escape key. The program plays a sound every time the animation
loop restarts. It attempts to show all the basic features of DirectX 8 simply.
It is not optimized so as to keep it as simple to understand as possible.

The main point to note is the that the animation is achieved by moving the
world transformation. Every single line is commented, an there are lengthy
explanations of each main function. Here is the full source code and comment to
view, but you can also download
it.

---***---SOURCE CODE STARTS HERE---***---

'-----------------------------------------------------------------

'

'  DX8 INTRODUCTION - DIRECTGRAPHICS,DIRECTSOUND, DIRECTINPUT

'

'             BY SIMON PRICE

'

'-----------------------------------------------------------------



' For this tutorial program you will need the DirectX8 for Visual

' Basic Type Library, from www.microsoft.com/directx



' You should also have the tutorial in HTML format, if you don't

' you can download it from my website www.VBgames.co.uk



' Any questions go to ihaveaquestionforsimonaboutdx8@VBgames.co.uk,

' or you could use a shorter address :) (si@VBgames.co.uk will do)

' Any bug reports go to the same address too please, as do comments

' feedback, suggestions, erm whatever you feel like



' Every time you start a project which will use DirectX8, you need

' to click on the menu Project -> References and a dialog box will

' pop up. Check the box which says "DirectX8 for Visual Basic Type

' Library" and click OK. Now VB will know all the types, classes

' enumerations and functions of DirectX8.



Option Explicit



' GLOBAL VARIABLE DECLARATIONS



' No matter what you do with DirectX8, you will need to start with

' the DirectX8 object. You will need to create a new instance of

' the object, using the New keyword, rather than just getting a

' pointer to it, since there's nowhere to get a pointer from yet (duh!).



Dim DX As New DirectX8



' The DirectInput8 object is used to get data from input devices

' such as the mouse and keyboard. This is what we will use it for

' in this tutorial, since they are the most common input devices.

' Notice how we don't create a new instance of the object, rather

' DirectX does that for us and we just get a pointer to it.



Dim DI As DirectInput8



' Now we need 2 devices - keyboard and mouse...



Dim Keyboard As DirectInputDevice8

Dim Mouse As DirectInputDevice8



' ...and a structure (type) to hold the data from each device. DI

' provides us a custom keyboard and mouse type, since they are

' commonly used



Dim KeyboardState As DIKEYBOARDSTATE

Dim MouseState As DIMOUSESTATE



' Next, we have DirectSound8, this can be used for many things, but

' for now we just play a sound from a .wav file



Dim DS As DirectSound8



' A sound buffer is a piece of memory in which the sound is stored.

' We use a secondary buffer, because a primary buffer can actually

' be heard though the speakers, and the sound needs to be mixed

' before we allow the user to hear that. In this tutorial, we let

' DirectSound worry about mixing and copying to the primary buffer

' to play the sound for us



Dim Sound As DirectSoundSecondaryBuffer8



' The DSBUFFER type holds a description of a sound buffer. We won't

' use any of the more advanced flags in this tutorial



Dim SoundDesc As DSBUFFERDESC



' The Direct3D8 object is responsible for all graphics, yes, even 2D



Dim D3D As Direct3D8



' The D3DX8 object contains lots of helper functions, mostly math

' to make Direct3D alot easier to use. Notice we create a new

' instance of the object using the New keyword.



Dim D3DX As New D3DX8



' The Direct3DDevice8 represents our rendering device, which could

' be a hardware or a software device. The great thing is we still

' use the same object no matter what it is



Dim D3Ddevice As Direct3DDevice8



' The D3DPRESENT_PARAMETERS type holds a description of the way

' in which DirectX will display it's rendering



Dim D3Dpp As D3DPRESENT_PARAMETERS



' The D3DMATERIAL8 type stores information on the material our

' polygons are rendered with, such as color



Dim Material As D3DMATERIAL8



' The Direct3DTexture8 object represents a piece of memory used to

' store a texture to be mapped onto our polygons



Dim Texture As Direct3DTexture8



' The Direct3DVertexBuffer8 object stores an array of vertices from which

' our polygons are made



Dim VertexBuffer As Direct3DVertexBuffer8



' The D3DVERTEX type stores vertices temporarily before we copy

' them into the vertex buffer



Dim Vertex(1 To 24) As D3DVERTEX



' The Direct3DIndexBuffer8 object stores the order in which our

' vertices are rendered



Dim IndexBuffer As Direct3DIndexBuffer8



' These integers are used to temporarily store indices before they

' are copied into the index buffer



Dim Index(1 To 36) As Integer



' This stores the rotation of the cubes



Dim Rotation As Single













' FORM_LOAD



' The whole program is started and controlled from here



Private Sub Form_Load()

    On Error Resume Next

    ' initialize directx

    If Init = False Then

        ' display error message

        MsgBox "Error! Could not initialize DirectX!"

    Else

        ' show form

        Show

        ' do main program loop

        MainLoop

        End If

    ' unload form and clean up directx

    Unload Me

End Sub





' FORM_UNLOAD



' Before the program ends, call the cleanup function



Private Sub Form_Unload(Cancel As Integer)

  CleanUp

End Sub











' INITIALIZATION



' In this function we initialize all the global DirectX objects. We

' basically get the DirectInput, DirectSound, and DirectGraphics

' engines started up, and retrieve pointers so we can manipulate them



Function Init() As Boolean



    'On Error GoTo InitFailed



    ' DIRECTINPUT



    ' Get a pointer to DirectInput

    Set DI = DX.DirectInputCreate()

    ' Check to see if the pointer is valid

    If DI Is Nothing Then GoTo InitFailed



    ' Get a pointer to keyboard and mouse device objects

    Set Keyboard = DI.CreateDevice("GUID_SysKeyboard")

    Set Mouse = DI.CreateDevice("guid_SysMouse")

    ' Check to see if pointers are valid

    If Keyboard Is Nothing Then GoTo InitFailed

    If Mouse Is Nothing Then GoTo InitFailed



    ' Set the data formats to the commmonly used keyboard and mouse

    Keyboard.SetCommonDataFormat DIFORMAT_KEYBOARD

    Mouse.SetCommonDataFormat DIFORMAT_MOUSE



    ' Set cooperative level, this tells DI how much control we need

    Keyboard.SetCooperativeLevel hWnd, DISCL_NONEXCLUSIVE Or DISCL_BACKGROUND

    Mouse.SetCooperativeLevel hWnd, DISCL_NONEXCLUSIVE Or DISCL_BACKGROUND



    ' Now we are ready to aquire (erm, get) our input devices

    Keyboard.Acquire

    Mouse.Acquire



    ' DIRECTSOUND



    ' Get a pointer to DirectSound

    Set DS = DX.DirectSoundCreate("")

    ' Check the pointer is valid

    If DS Is Nothing Then GoTo InitFailed



    ' Set cooperative level, we only need normal functionality

    DS.SetCooperativeLevel hWnd, DSSCL_NORMAL



    ' Create a sound buffer from a .wav file. We provide a filename

    ' and a DSBUFFER type, which stores any special information

    ' about the buffer we might need to know (not used here)

    Set Sound = DS.CreateSoundBufferFromFile(App.Path & "sound.wav", SoundDesc)

    ' Check the pointer is valid

    If Sound Is Nothing Then GoTo InitFailed



    ' DIRECT3D



    ' Get a pointer to Direct3D

    Set D3D = DX.Direct3DCreate()

    ' Check the pointer is valid

    If D3D Is Nothing Then GoTo InitFailed



    ' Fill the D3DPRESENT_PARAMETERS type, describing how DirectX should

    ' display it's renders



    With D3Dpp

        ' set the most common fullscreen display mode

        .Windowed = False ' the app is not in a window

        .BackBufferWidth = 640 '
the size of the screen

        .BackBufferHeight = 480

        .BackBufferFormat = D3DFMT_R5G6B5 ' the color depth format (16 bit)

        ' the swap effect determines how the graphics get from

        ' the backbuffer to the screen - note : D3DSWAPEFFECT_DISCARD

        ' means that every time the render is presented, the backbuffer

        ' image is destroyed, so everything must be rendered again

        .SwapEffect = D3DSWAPEFFECT_DISCARD

        ' request a 16 bit z-buffer - this depth sorts the scene

        ' so we can't see polygons that are behind other polygons

        .EnableAutoDepthStencil = 1

        .AutoDepthStencilFormat = D3DFMT_D16

        ' 1 backbuffer

        .BackBufferCount = 1

       End With



    ' Create the rendering device. Here we request a hardware rasterization.

    ' If your computer does not have this, the request may fail, so use

    ' D3DDEVTYPE_REF instead of D3DDEVTYPE_HAL if this happens. A real

    ' program would be able to detect an error and automatically switch device.

    ' We also request software vertex processing, which means the CPU has to

    ' transform and light our geometry

    Set D3Ddevice = D3D.CreateDevice(D3DADAPTER_DEFAULT, D3DDEVTYPE_HAL,
hWnd,  D3DCREATE_SOFTWARE_VERTEXPROCESSING, D3Dpp)

    ' check the pointer is valid

    If D3Ddevice Is Nothing Then GoTo InitFailed



    ' Set rendering options

    D3Ddevice.SetRenderState D3DRS_CULLMODE, D3DCULL_NONE

    D3Ddevice.SetRenderState D3DRS_ZENABLE, D3DZB_TRUE ' enable z buffering

    D3Ddevice.SetRenderState D3DRS_FILLMODE, D3DFILL_SOLID ' render solid polygons

    D3Ddevice.SetRenderState D3DRS_LIGHTING, True ' enable lighting

    D3Ddevice.SetRenderState D3DRS_AMBIENT, vbWhite ' use ambient white light

    

    ' Set the material properties

    With Material.Ambient

        .a = 1: .r = 1: .g = 1: .b = 1

    End With



    ' Create a texture surface from a file

    Set Texture = D3DX.CreateTextureFromFile(D3Ddevice, App.Path & " exture.bmp")

    ' Check the pointer is valid

    If Texture Is Nothing Then GoTo InitFailed



    ' Set the material and texture as the current ones to render from

    D3Ddevice.SetMaterial Material

    D3Ddevice.SetTexture 0, Texture



    ' Create a vertex buffer, using default usage and specifying enough memory for 24 vertices of format        
D3DFVF_VERTEX

    Set VertexBuffer = D3Ddevice.CreateVertexBuffer(24 * Len(Vertex(1)), 0, D3DFVF_VERTEX, D3DPOOL_DEFAULT)

    ' Check pointer is valid

    If VertexBuffer Is Nothing Then GoTo InitFailed



    ' Create an index buffer, using default uage and specifying enough memory for 36 16 bit integers

    Set IndexBuffer = D3Ddevice.CreateIndexBuffer(36 * Len(Index(1)), 0, D3DFMT_INDEX16, D3DPOOL_DEFAULT)

    ' Check pointer is valid

    If IndexBuffer Is Nothing Then GoTo InitFailed



    ' Now we make a cube shape out of our vetices

    Vertex(1) = MakeVertex(-1, 1, -1, 0, 0, -1, 0, 0)

    Vertex(2) = MakeVertex(1, 1, -1, 0, 0, -1, 1, 0)

    Vertex(3) = MakeVertex(-1, -1, -1, 0, 0, -1, 0, 1)

    Vertex(4) = MakeVertex(1, -1, -1, 0, 0, -1, 1, 1)

    Vertex(5) = MakeVertex(1, 1, -1, 0, 0, 1, 0, 0)

    Vertex(6) = MakeVertex(-1, 1, -1, 0, 0, 1, 1, 0)

    Vertex(7) = MakeVertex(1, -1, -1, 0, 0, 1, 0, 1)

    Vertex(8) = MakeVertex(-1, -1, -1, 0, 0, 1, 1, 1)



    Vertex(9) = MakeVertex(-1, 1, 1, -1, 0, 0, 0, 0)

    Vertex(10) = MakeVertex(-1, 1, -1, -1, 0, 0, 1, 0)

    Vertex(11) = MakeVertex(-1, -1, 1, -1, 0, 0, 0, 1)

    Vertex(12) = MakeVertex(-1, -1, -1, -1, 0, 0, 1, 1)

    Vertex(13) = MakeVertex(1, 1, -1, 1, 0, 0, 0, 0)

    Vertex(14) = MakeVertex(1, 1, 1, 1, 0, 0, 1, 0)

    Vertex(15) = MakeVertex(1, -1, -1, 1, 0, 0, 0, 1)

    Vertex(16) = MakeVertex(1, -1, 1, 1, 0, 0, 1, 1)



    Vertex(17) = MakeVertex(-1, 1, -1, 0, 1, 0, 0, 0)

    Vertex(18) = MakeVertex(1, 1, -1, 0, 1, 0, 1, 0)

    Vertex(19) = MakeVertex(-1, 1, 1, 0, 1, 0, 0, 1)

    Vertex(20) = MakeVertex(1, 1, 1, 0, 1, 0, 1, 1)

    Vertex(21) = MakeVertex(-1, -1, -1, 0, -1, 0, 0, 0)

    Vertex(22) = MakeVertex(1, -1, -1, 0, -1, 0, 1, 0)

    Vertex(23) = MakeVertex(-1, -1, 1, 0, -1, 0, 0, 1)

    Vertex(24) = MakeVertex(1, -1, 1, 0, -1, 0, 1, 1)



    ' Copy the vertices into the vertex buffer

  D3DVertexBuffer8SetData VertexBuffer, 0, 24 * Len(Vertex(1)), 0, Vertex(1)



    ' Make a list which tells the order in which to render these vertices

    MakeIndices 1, 2, 3, 3, 2, 4, 5, 6, 7, 7, 6, 8, 9, 10, 11, 11, 10, 12, 13, 14, 15, 15, 14, 16, 17, 18, 19, 19, 18, 20, 21, 22, 23, 23, 22, 24



    ' Copy the indices into the index buffer

    D3DIndexBuffer8SetData IndexBuffer, 0, 36 * Len(Index(1)), 0, Index(1)



    ' Set the vertex format

    D3Ddevice.SetVertexShader D3DFVF_VERTEX



    ' Set the vertex and index buffers as current ones to render from

    D3Ddevice.SetStreamSource 0, VertexBuffer, Len(Vertex(1))

    D3Ddevice.SetIndices IndexBuffer, -1



    ' Initializtion is complete!

    Init = True

    Exit Function



InitFailed: ' the initialization function has failed

    Init = False



End Function











' MAKEVECTOR



' This function creates vectors



Function MakeVector(x As Single, y As Single, z As Single) As D3DVECTOR

    With MakeVector

        .x = x

        .y = y

        .z = z

    End With

End Function











' MAKEVERTEX



' This function creates vertices



Function MakeVertex(x As Single, y As Single, z As Single, nx As Single, ny As Single, nz As Single, tu As Single, tv As Single) As D3DVERTEX

    With MakeVertex

        .x = x

        .y = y

        .z = z

        .nx = nx

        .ny = ny

        .nz = nz

        .tu = tu

        .tv = tv

    End With

End Function











' MAKEINDICES



' This function creates a list of indices



Function MakeIndices(ParamArray Indices()) As Integer()

    Dim i As Integer

    For i = LBound(Indices) To UBound(Indices)

        Index(i + 1) = Indices(i)

    Next

End Function











' MAINLOOP



' This sub animates the scene by moving the positions of the

' cubes and the camera position, then renders the cubes. It

' checks to see if the escape key has been pressed and loops

' if it has not.



Sub MainLoop()

' the mathematical constant pi

Const PI = 3.1415

' the speed of animation

Const SPEED = 0.01

' matrices for animation and cameras

Dim matTranslation As D3DMATRIX, matRotation As D3DMATRIX, matScaling As D3DMATRIX, matView As D3DMATRIX, matProjection As D3DMATRIX, matTransform As D3DMATRIX

' camera position

Dim CameraPos As D3DVECTOR

On Error Resume Next

    Do

        ' let Windows messages be executed

        DoEvents

        ' get keyboard and mouse data

        Keyboard.GetDeviceStateKeyboard KeyboardState

        Mouse.GetDeviceStateMouse MouseState

        ' if escape was pressed, exit program

        If KeyboardState.Key(DIK_ESCAPE) Then Exit Do

        ' move camera with mouse

        CameraPos.y = CameraPos.y + MouseState.lY / 10

        CameraPos.z = -2

        ' set camera position, using mouse data

        D3DXMatrixLookAtLH matView, MakeVector(CameraPos.x, CameraPos.y, CameraPos.z), MakeVector(0, 0, 0), MakeVector(0, 1, 0)

        D3Ddevice.SetTransform D3DTS_VIEW, matView

        D3DXMatrixPerspectiveFovLH matProjection, PI / 3, 0.75, 0.1, 10000

        D3Ddevice.SetTransform D3DTS_PROJECTION, matProjection

        ' move the rotation angle

        Rotation = Rotation + SPEED

        If Rotation > 2 * PI Then

            Rotation = Rotation - 2 * PI

           
' once per rotation, play a sound

            Sound.Play DSBPLAY_DEFAULT

        End If

        ' clear the rendering device backbuffer and z-buffer

        D3Ddevice.Clear 0, ByVal 0, D3DCLEAR_TARGET Or D3DCLEAR_ZBUFFER, vbWhite, 1#, 0

        ' start rendering

        D3Ddevice.BeginScene

        ' create rotation matrix

        D3DXMatrixRotationYawPitchRoll matTransform, Rotation * 2, Rotation, Rotation

        ' set the world matrix to normal

        D3Ddevice.SetTransform D3DTS_WORLD, matTransform

        ' draw the medium cube

        DrawCube

        ' create movement, rotation and scale matrices

        D3DXMatrixTranslation matTranslation, 0, 0, 4

        D3DXMatrixRotationYawPitchRoll matRotation, 0, Rotation * 2, Rotation * 4

        D3DXMatrixScaling matScaling, 0.5, 0.5, 0.5

        ' combine them

        D3DXMatrixMultiply matTransform, matRotation, matTranslation

        D3DXMatrixMultiply matTransform, matTransform, matScaling

        ' transform the world matrix

        D3Ddevice.MultiplyTransform D3DTS_WORLD, matTransform

        ' draw the small cube

        DrawCube

        ' create movement, rotation and scale matrices

        D3DXMatrixTranslation matTranslation, -3, -3, -3

        D3DXMatrixRotationYawPitchRoll matRotation, Rotation * 8, 0, Rotation * 6

        D3DXMatrixScaling matScaling, 0.5, 0.5, 0.5

        ' combine them

        D3DXMatrixMultiply matTransform, matTranslation, matRotation

        D3DXMatrixMultiply matTransform, matTransform, matScaling

        ' transform the world matrix

        D3Ddevice.MultiplyTransform D3DTS_WORLD, matTransform

        ' draw the small cube

        DrawCube

        ' end rendering

        D3Ddevice.EndScene

        ' present the contents of the backbuffer by flipping it to the screen

        D3Ddevice.Present ByVal 0, ByVal 0, 0, ByVal 0

    Loop

End Sub











' DRAWCUBE



' Draws the cube



Sub DrawCube()

On Error Resume Next

    ' draw 12 triangles, in a cube shape, onto the backbuffer of the rendering device

    D3Ddevice.DrawIndexedPrimitive D3DPT_TRIANGLELIST, 0, 36, 0, 12

End Sub









' CLEANUP



' This unloads all the DirectX objects - we destroy objects we

' have created, an disassociate our pointers from objects

' create by DirectX, so then DirectX can destroy them. Failing

' to call this sub can cause memory to be lost.



Sub CleanUp()



On Error Resume Next



    Set Keyboard = Nothing

    Set Mouse = Nothing

    Set DI = Nothing



    Set Sound = Nothing

    Set DS = Nothing



    Set Texture = Nothing

    Set D3Ddevice = Nothing

    Set D3DX = Nothing

    Set D3D = Nothing



End Sub

---***---SOURCE CODE ENDS HERE---***---

Hey - does somebody have a HTML VB syntax color highlighter? As you can see,
I got fed up and didn't color in the keywords!

What you have learnt

• Initialization - getting DirectX objects - loading textures, sounds,
    geometry, vertex and index buffers, getting input devices


• Rendering - How to draw and present texture mapped triangles


• Sound - erm, how to play one


• Input - how to read the keyboard and mouse


• Animation - how to use matrices to perform complex animation


• Alot of keywords and terms

What you should do next

• I've left a bug in the program for you on purpose! One face of each cube
    is not rendered! Find the bug and kill it! I do know the answer, honestly,
    but I'm not telling because debugging is a major part of programming for you
    to learn!


• Try some different shapes, animation, colors, textures, sounds, camera
    movements


• Try adding a background


• Make the program more interactive, maybe even make a puzzle or game


• See some of my other programs on my website for more ideas

Future Tutorials

There's still lots more to learn and more advanced tutorials will come when I
get the time. Some major topics include 3D sound, lighting, and loading model
files. Give me some feedback on what you need to know.

What I'd like you to do now

• Visit my website : www.VBgames.co.uk
    - and if you have your own programming site please swap links with me


• Please vote for me - on www.planet-source-code.com 


• Give me some feedback - go to www.planet-source-code.com
    and tell me what was good and what was bad, suggestions, comments, anything.
    Tell me why you voted the rating that you did.


• Hey, my request to write a book got turned down! (erm, private joke with
    someone)

Credits

There are lots of sources from where my information came from. Mainly
Microsoft's DirectX SDK (as much as I hate them, DirectX rules!). Many tutorials
on www.planet-source-code.com
and www.gamedev.net , and also thanks to
Richard Hayden for his example program.

Disclaimer

This tutorial might be totally wrong so it's not my fault if something goes
wrong. You've been warned (right at the end, after you messed up your PC)!