3D Graphics APIs Part II: DirectX Graphics rel' 9'0

1
Fac. of Comp., Eng. Tech. Staffordshire
University
3D Computer Graphics
3D Graphics APIs Part II DirectX Graphics
(rel. 9.0)
Dr. Claude C. Chibelushi
2
Outline

• Introduction
• Programming Basics
• Initialisation
• Polygonal shape modelling
• Geometric transformations
• Hidden surface removal
• Illumination and shading
• Rendering and display
• Summary

3
Introduction

• DirectX
• Set of APIs for developing games and other
  multimedia applications for MS Windows platform
• Supports
• 2-D, 3-D graphics
• sound, music (control of sound mixing, sound
  output )
• user input (joystick, keyboard, mouse), force
  feedback
• multimedia streaming, network communication
• multiplayer games

4
Introduction

• DirectX
• DirectX APIs
• DirectX Graphics
• integration of Direct3D (3D graphics) and
  DirectDraw (access to video card)
• DirectPlay
• multiplayer games via network
• DirectInput
• access to input devices
• DirectX Audio
• integration of DirectSound and DirectMusic
• DirectShow, DirectAnimation

5
Introduction

• DirectX
• Portability
• provides hardware abstraction layer (HAL)
• uses software drivers for communication between
  multimedia software and computer hardware
• Components of DirectX Graphics
• Direct3D (D3D)
• core rendering functions, types, and constants
• Direct3DX (D3DX)
• utility library

6
Introduction

• DirectX Graphics sample features
• Programmable vertex and pixel processing
  languages
• developer can write custom shaders
• Multisampling rendering
• full-scene anti-aliasing, motion blur,
  depth-of-field blur
• Point sprite support
• particle systems
• Higher-order primitives
• smoother geometric shapes

7
Introduction

• DirectX Graphics
• Layered architecture of graphics system

8
Programming Basics

• Win32 programming
• run-time requirements for DirectX 9
• Microsoft Windows 98, Windows Me, Windows 2000,
  Windows XP
• dynamic link libraries d3d.dll
• libraries d3d9.lib, d3dx9dt.lib,
• header files d3d9.h, d3dx9.h,

9
Programming Basics

• Typical program steps
• create application window
• create and initialise Direct3D objects
• invoke appropriate instructions / commands for
• event handling
• defining and rendering synthetic worlds

10
Programming Basics

• Initialisation of Direct3D
• create and initialise Direct3D objects
• e.g. D3D rendering device, D3D vertex buffer
• COM interface of object used for
• object manipulation
• creation of other objects required for scene
  rendering

11
Initialisation

• Sample code
• LPDIRECT3D9 g_pD3D NULL
  // object used to create D3DDevice
• LPDIRECT3DDEVICE9 g_pd3dDevice NULL //
  rendering device
• g_pD3D Direct3DCreate9( D3D_SDK_VERSION )
• g_pD3D-gtCreateDevice( D3DADAPTER_DEFAULT,
  D3DDEVTYPE_HAL, hWnd, D3DCREATE_SOFTWARE_VERTE
  XPROCESSING, d3dpp, g_pd3dDevice )

12
Graphics Pipeline

• DirectX 8
• graphics pipeline

13
Graphics Pipeline

• DirectX 9 graphics pipeline

14
Polygonal shape modelling

• Polygon defined as group of vertices
• support for custom vertex type
• flexible vertex format (FVF) each vertex may
  consist of
• x, y, z coordinates
• colour
• vertex normal
• texture map coordinates
• light map coordinates
• vertex buffers for geometry storage

15
Polygonal shape modelling

• Mesh data architecture
• vertex buffer
• face index buffer face has 3 vertex indexes
• attribute buffer
• materials, textures
• index into attributes table
• adjacency buffer face has index to adjacent faces

16
Polygonal shape modelling

• Simple general procedure
• Specify vertex format
• Create array of vertices
• Store array in vertex buffer
• May explicitly specify drawing as
• point list, line list / strip, triangle list /
  strip / fan
• Alternative
• Use D3DX to load mesh from file

17
Polygonal shape modelling

• Definition of custom vertex type sample code
• LPDIRECT3DVERTEXBUFFER9 g_pVB NULL //
  buffer to hold vertices
• // structure for custom vertex type
• struct CUSTOMVERTEX
• FLOAT x, y, z, rhw // vertex position
• D3DXVECTOR3 normal // surface normal for
  vertex
• // custom FVF (describes custom vertex structure)
  
• define D3DFVF_CUSTOMVERTEX (D3DFVF_XYZD3DFVF_NOR
  MAL)

18
Polygonal shape modelling

• Definition of custom vertex type sample code
• LPDIRECT3DVERTEXBUFFER9 g_pVB NULL //
  buffer to hold vertices
• // structure for custom vertex type
• struct CUSTOMVERTEX
• FLOAT x, y, z, rhw // vertex position
• DWORD color // vertex color
• // custom FVF (describes custom vertex structure)
• define D3DFVF_CUSTOMVERTEX (D3DFVF_XYZRHWD3DFVF_
  DIFFUSE)

19
Polygonal shape modelling

• Setting up vertex buffer sample code
• CUSTOMVERTEX g_Vertices
• 150.0f, 50.0f, 0.5f, 1.0f, 0xffff0000,
  , // x, y, z, rhw, color
• 250.0f, 250.0f, 0.5f, 1.0f, 0xff00ff00,
  ,
• 50.0f, 250.0f, 0.5f, 1.0f, 0xff00ffff,
  ,
• g_pd3dDevice-gtCreateVertexBuffer(
  3sizeof(CUSTOMVERTEX),
• 
  0, D3DFVF_CUSTOMVERTEX,
• 
  D3DPOOL_DEFAULT, g_pVB )
• VOID pVertices
• g_pVB-gtLock( 0, sizeof(g_Vertices),
  (BYTE)pVertices, 0 ) )
• memcpy( pVertices, g_Vertices, sizeof(g_Vertices)
  )

20
Geometric Transformations

• Homogeneous matrices
• 4 x 4 transformation matrices
• declared using structures
• D3DMATRIX, D3DXMATRIX, ...
• vM notation, hence
• left-to-right matrix concatenation order
• see e.g. translation matrix on next slide

21
Geometric Transformations

• Homogeneous matrices

22
Geometric Transformations

• Homogeneous matrices
• Sample functions
• D3DXMatrixIdentity(), D3DXMatrixScaling(),
  D3DXMatrixTranslation(), D3DXMatrixRotationY(),
  D3DXMatrixTransformation(), ...
• D3DXMatrixMultiply(), D3DXMatrixTranspose(),
  D3DXMatrixInverse(), ...

23
Geometric Transformations

• Homogeneous matrices (sample code)
• Declaring and initialising scaling matrix
• D3DMATRIX scMat
• sX, 0.0f, 0.0f, 0.0f,
• 0.0f, sY, 0.0f, 0.0f,
• 0.0f, 0.0f, sZ, 0.0f,
• 0.0f, 0.0f, 0.0f, 1.0f

24
Geometric Transformations

• Homogeneous matrices (sample code)
• Declaring and setting translation matrix
• D3DXMATRIX trMat
• float tx 10.0, ty 0.0, tz 0.0
• D3DXMatrixTranslation (trMat, tx, ty, tz)

25
Geometric Transformations

• Homogeneous matrices (sample code)
• Declaring and setting rotation matrix
• D3DXMATRIX rotMat
• float thetaX 30.0 / Pitch /, thetaY 0.0 /
  Yaw /, thetaZ 45.0 / Roll /
• / e.g. rotation about x-axis /
• D3DXMatrixRotationX(rotMat, thetaX)
• / e.g. rotation about all 3 axes /
• D3DXMatrixRotationYawPitchRoll(rotMat, thetaY,
  thetaX, thetaZ)

26
Geometric Transformations

• Homogeneous matrices (sample code)
• Matrix concatenation
• D3DXMATRIX resMat
• / declare / initialise matrices rotMat and
  trMat /
• / rotation followed by translation /
• D3DXMatrixMultiply(resMat, rotMat, trMat)

27
Geometric Transformations

• Viewing pipeline
• Three main matrices in pipeline
• world matrix
• model-to-world transformation
• view matrix
• world-to-view transformation
• projection matrix
• projection and viewport transformation

28
Geometric Transformations

• Viewing pipeline
• Transformation matrices
• automatic concatenation of pipeline matrices
• order in which matrices defined not important
• but combination order always world x view x
  projection
• flags used for setting matrix in rendering device
  object
• D3DTS_WORLD, D3DTS_VIEW, D3DTS_PROJECTION

29
Geometric Transformations

• Viewing pipeline
• Specification of camera
• D3DXMatrixLookAtLH()
• defines position, view-plane normal, and view-up
  vector
• builds left-handed camera coordinate system
• sets left-handed, look-at matrix
• Specification of projection e.g. perspective
• D3DXMatrixPerspectiveFovLH(...)
• sets left-handed perspective projection matrix

30
Geometric Transformations

• Viewing pipeline sample code
• (world matrix)
• // Set up world matrix
• D3DXMATRIX matWorld
• D3DXMatrixRotationY( matWorld,
  timeGetTime()/150.0f ) // for rotation about
  y-axis
• g_pd3dDevice-gtSetTransform( D3DTS_WORLD,
  matWorld )

31
Geometric Transformations

• Viewing pipeline sample code
• (view matrix)
• // Set up our view matrix (give eye point,
  look-at point, and up direction)
• D3DXMATRIX matView
• D3DXMatrixLookAtLH( matView, D3DXVECTOR3(
  0.0f, 3.0f,-5.0f ),
• D3DXVECTOR3(
  0.0f, 0.0f, 0.0f ),
• D3DXVECTOR3(
  0.0f, 1.0f, 0.0f ) )
• g_pd3dDevice-gtSetTransform( D3DTS_VIEW,
  matView )

32
Geometric Transformations

• Viewing pipeline sample code
• (projection matrix)
• // Set up projection matrix (give field of view,
  aspect ratio, near and far clipping planes
• D3DXMATRIX matProj
• D3DXMatrixPerspectiveFovLH( matProj,
  D3DX_PI/4, 1.0f, 1.0f, 100.0f )
• g_pd3dDevice-gtSetTransform( D3DTS_PROJECTION,
  matProj )

33
Hidden Surface Removal

• Face culling
• enabling / disabling
• g_pd3dDevice-gtSetRenderState( D3DRS_CULLMODE,
  D3DCULL_NONE ) // turn off culling
• z-buffer
• enabling / disabling
• g_pd3dDevice-gtSetRenderState( D3DRS_ZENABLE, TRUE
  ) // turn on the zbuffer
• initialisation
• specify value for clearing colour, depth, and
  stencil buffers
• g_pd3dDevice-gtClear(...)

34
Illumination and Shading

• Specification of surface orientation / material
• specification of normals
• see polygonal shape modelling
• specification of material
• data type D3DMATERIAL9
• Specification of lights
• data type D3DLIGHT9

35
Illumination and Shading

• Lighting enabling / disabling
• g_pd3dDevice-gtSetRenderState( D3DRS_LIGHTING,
  FALSE ) // turn off D3D lighting
• g_pd3dDevice-gtSetRenderState( D3DRS_AMBIENT,
  0xffffffff ) // turn on ambient lighting

36
Illumination and Shading

• Sample code (materials)
• // set up material (diffuse and ambient colours)
• D3DMATERIAL9 mtrl
• ZeroMemory( mtrl, sizeof(D3DMATERIAL9) )
• mtrl.Diffuse.r mtrl.Ambient.r
  mtrl.Diffuse.g mtrl.Ambient.g 1.0f
• mtrl.Diffuse.b mtrl.Ambient.b 0.0f
  mtrl.Diffuse.a mtrl.Ambient.a 1.0f
• g_pd3dDevice-gtSetMaterial( mtrl )

37
Illumination and Shading

• Sample code (lights)
• // set up directional light and set
  D3DRS_LIGHTING renderstate to enable lighting
• D3DXVECTOR3 vecDir D3DLIGHT9 light
• ZeroMemory( light, sizeof(D3DLIGHT9) )
• light.Type D3DLIGHT_DIRECTIONAL
• light.Diffuse.r 1.0f light.Diffuse.g
  1.0f light.Diffuse.b 1.0f
• vecDir D3DXVECTOR3(1.0f, 1.0f, 0.5f)
• D3DXVec3Normalize( (D3DXVECTOR3)light.Direct
  ion, vecDir )
• light.Range 1000.0f
• g_pd3dDevice-gtSetLight( 0, light )
  g_pd3dDevice-gtLightEnable( 0, TRUE )
• g_pd3dDevice-gtSetRenderState( D3DRS_LIGHTING,
  TRUE )
• g_pd3dDevice-gtSetRenderState( D3DRS_AMBIENT,
  0x00202020 )

38
Rendering and Display

• Sample code
• // Clear the backbuffer to a blue color
• g_pd3dDevice-gtClear( 0, NULL,
  D3DCLEAR_TARGET, D3DCOLOR_XRGB(0,0,255), 1.0f, 0
  )
• g_pd3dDevice-gtBeginScene() // Begin the
  scene
• SetupLights() // set up lights and
  materials
• SetupMatrices() // set up world, view, and
  projection matrices
• // Draw the triangles in the vertex buffer
• g_pd3dDevice-gtSetStreamSource( 0, g_pVB, 0,
  sizeof(CUSTOMVERTEX) )
• g_pd3dDevice-gtSetFVF( D3DFVF_CUSTOMVERTEX )
• g_pd3dDevice-gtDrawPrimitive(
  D3DPT_TRIANGLELIST, 0, 1 )
• g_pd3dDevice-gtEndScene() // End the scene
• g_pd3dDevice-gtPresent( NULL, NULL, NULL, NULL
  ) // send back-buffer content to display

39
Rendering and Display

• Sample code
• Mesh display mode
• wireframe
• g_pd3dDevice-gtSetRenderState(D3DRS_FILLMODE,
  D3DFILL_WIREFRAME) // wireframe display
• solid
• g_pd3dDevice-gtSetRenderState(D3DRS_FILLMODE,
  D3DFILL_SOLID) // solid mesh display

40
Suggested Reading

• http//www.microsoft.com/directx/default.asp

41
Summary

• DirectX set of APIs for MS Windows games and
  multimedia applications
• Sample features of Direct3D
• polygonal shape modelling flexible vertex format
• hidden surface removal
• back-face culling
• z-buffer / clipping
• illumination and shading
• ambient, diffuse, specular illumination models
• programmable vertex / pixel shaders