Matrices

 

//-----------------------------------------------------------------------------
// File: Matrices.cpp
//
// Desc: Now that we know how to create a device and render some 2D vertices,
//       this tutorial goes the next step and renders 3D geometry. To deal with
//       3D geometry we need to introduce the use of 4x4 matrices to transform
//       the geometry with translations, rotations, scaling, and setting up our
//       camera.
//
//       Geometry is defined in model space. We can move it (translation),
//       rotate it (rotation), or stretch it (scaling) using a world transform.
//       The geometry is then said to be in world space. Next, we need to
//       position the camera, or eye point, somewhere to look at the geometry.
//       Another transform, via the view matrix, is used, to position and
//       rotate our view. With the geometry then in view space, our last
//       transform is the projection transform, which "projects" the 3D scene
//       into our 2D viewport.
//
//       Note that in this tutorial, we are introducing the use of D3DX, which
//       is a set of helper utilities for D3D. In this case, we are using some
//       of D3DX's useful matrix initialization functions. To use D3DX, simply
//       include <d3dx9.h> and link with d3dx9.lib.
//
// Copyright (c) Microsoft Corporation. All rights reserved.
//-----------------------------------------------------------------------------
#include <Windows.h>
#include <mmsystem.h>
#include <d3dx9.h>

 

//-----------------------------------------------------------------------------
// Global variables
//-----------------------------------------------------------------------------
LPDIRECT3D9             g_pD3D       = NULL; // Used to create the D3DDevice
LPDIRECT3DDEVICE9       g_pd3dDevice = NULL; // Our rendering device
LPDIRECT3DVERTEXBUFFER9 g_pVB        = NULL; // Buffer to hold vertices

// A structure for our custom vertex type
struct CUSTOMVERTEX
{
    FLOAT x, y, z;      // The untransformed, 3D position for the vertex
    DWORD color;        // The vertex color
};

// Our custom FVF, which describes our custom vertex structure
#define D3DFVF_CUSTOMVERTEX (D3DFVF_XYZ|D3DFVF_DIFFUSE)

 

//-----------------------------------------------------------------------------
// Name: InitD3D()
// Desc: Initializes Direct3D
//-----------------------------------------------------------------------------
HRESULT InitD3D( HWND hWnd )
{
    // Create the D3D object.
    if( NULL == ( g_pD3D = Direct3DCreate9( D3D_SDK_VERSION ) ) )
        return E_FAIL;

    // Set up the structure used to create the D3DDevice
    D3DPRESENT_PARAMETERS d3dpp;
    ZeroMemory( &d3dpp, sizeof(d3dpp) );
    d3dpp.Windowed = TRUE;
    d3dpp.SwapEffect = D3DSWAPEFFECT_DISCARD;
    d3dpp.BackBufferFormat = D3DFMT_UNKNOWN;

    // Create the D3DDevice
    if( FAILED( g_pD3D->CreateDevice( D3DADAPTER_DEFAULT, D3DDEVTYPE_HAL, hWnd,
                                      D3DCREATE_SOFTWARE_VERTEXPROCESSING,
                                      &d3dpp, &g_pd3dDevice ) ) )
    {
        return E_FAIL;
    }

    // Turn off culling, so we see the front and back of the triangle
 // 컬링 기능을 끈다. 삼각형의 앞 뒷면을 모두 렌더링 한다.
    g_pd3dDevice->SetRenderState( D3DRS_CULLMODE, D3DCULL_NONE );

    // Turn off D3D lighting, since we are providing our own vertex colors
 // 정점에 색깔값이 잇으므로 광원 기능르 끈다.
    g_pd3dDevice->SetRenderState( D3DRS_LIGHTING, FALSE );

    return S_OK;
}

 

//-----------------------------------------------------------------------------
// Name: InitGeometry()
// Desc: Creates the scene geometry
//-----------------------------------------------------------------------------
HRESULT InitGeometry()
{
    // Initialize three vertices for rendering a triangle
    CUSTOMVERTEX g_Vertices[] =
    {
        { -1.0f,-1.0f, 0.0f, 0xffff0000, },
        {  1.0f,-1.0f, 0.0f, 0xff0000ff, },
        {  0.0f, 1.0f, 0.0f, 0xffffffff, },
    };

    // Create the vertex buffer.
    if( FAILED( g_pd3dDevice->CreateVertexBuffer( 3*sizeof(CUSTOMVERTEX),
                                                  0, D3DFVF_CUSTOMVERTEX,
                                                  D3DPOOL_DEFAULT, &g_pVB, NULL ) ) )
    {
        return E_FAIL;
    }

    // Fill the vertex buffer.
    VOID* pVertices;
    if( FAILED( g_pVB->Lock( 0, sizeof(g_Vertices), (void**)&pVertices, 0 ) ) )
        return E_FAIL;
    memcpy( pVertices, g_Vertices, sizeof(g_Vertices) );
    g_pVB->Unlock();

    return S_OK;
}

 

//-----------------------------------------------------------------------------
// Name: Cleanup()
// Desc: Releases all previously initialized objects
//-----------------------------------------------------------------------------
VOID Cleanup()
{
    if( g_pVB != NULL )
        g_pVB->Release();

    if( g_pd3dDevice != NULL )
        g_pd3dDevice->Release();

    if( g_pD3D != NULL )
        g_pD3D->Release();
}

 

//-----------------------------------------------------------------------------
// Name: SetupMatrices()
// Desc: Sets up the world, view, and projection transform matrices.
//-----------------------------------------------------------------------------
VOID SetupMatrices()
{
    // For our world matrix, we will just rotate the object about the y-axis.
 // 월드 행렬
    D3DXMATRIXA16 matWorld;

    // Set up the rotation matrix to generate 1 full rotation (2*PI radians)
    // every 1000 ms. To avoid the loss of precision inherent in very high
    // floating point numbers, the system time is modulated by the rotation
    // period before conversion to a radian angle.
 // float연산의 정밀도를 위해서 1000으로 나머지 연산한다.
    UINT  iTime  = timeGetTime() % 1000;
 // 1000 밀리초마다 한바퀴씩 (2 * pi)회전 애니메이션 행렬을 만든다.
    FLOAT fAngle = iTime * (2.0f * D3DX_PI) / 1000.0f;
 // Y축을 회전축을 회전 행렬을 생성한다.
    D3DXMatrixRotationY( &matWorld, fAngle );
 // 생성한 회전 행렬을 월드행렬로 디바이스에 설정한다. 
    g_pd3dDevice->SetTransform( D3DTS_WORLD, &matWorld );

    // Set up our view matrix. A view matrix can be defined given an eye point,
    // a point to lookat, and a direction for which way is up. Here, we set the
    // eye five units back along the z-axis and up three units, look at the
    // origin, and define "up" to be in the y-direction.
 // 뷰행렬을 정의하기 위해서는 3가지 값이 필요하다.
    D3DXVECTOR3 vEyePt( 0.0f, 3.0f,-5.0f );  // 1. 눈의 위치 ( 0, 3.0, -5 )
    D3DXVECTOR3 vLookatPt( 0.0f, 0.0f, 0.0f ); // 2. 눈이 바라보는 위치 ( 0, 0, 0 )
    D3DXVECTOR3 vUpVec( 0.0f, 1.0f, 0.0f );  // 3. 천정 방향을 나타내는 상방 벡터 ( 0, 1, 0 )
    D3DXMATRIXA16 matView;
    D3DXMatrixLookAtLH( &matView, &vEyePt, &vLookatPt, &vUpVec ); // 1, 2, 3 의 값으로 뷰 행렬 생성
    g_pd3dDevice->SetTransform( D3DTS_VIEW, &matView ); // 생성한 뷰 행렬을 디바이스에 설정

    // For the projection matrix, we set up a perspective transform (which
    // transforms geometry from 3D view space to 2D viewport space, with
    // a perspective divide making objects smaller in the distance). To build
    // a perpsective transform, we need the field of view (1/4 pi is common),
    // the aspect ratio, and the near and far clipping planes (which define at
    // what distances geometry should be no longer be rendered).

 // 프로젝션 행렬을 정의하기 위해서는 시야각( FOV:Field Of View )과 종횡비( aspect ratio ),
 // 클리핑 평면의 값이 필요하다
    D3DXMATRIXA16 matProj;
 // matProj  : 값이 설정될 행렬
 // D3DX_PI / 4 : FOV( D3DX_PI / 4 = 45도 )
 // 1.0f   : 종횡비
 // 1.0f   : 근접 클리핑 평면( near clipping plane )
 // 100.0f  : 원거리 클리핑 평면( far clipping plane )
    D3DXMatrixPerspectiveFovLH( &matProj, D3DX_PI/4, 1.0f, 1.0f, 100.0f );
 // 생성한 프로젝션 행렬을 디바이스에 설정
    g_pd3dDevice->SetTransform( D3DTS_PROJECTION, &matProj );
}

 

//-----------------------------------------------------------------------------
// Name: Render()
// Desc: Draws the scene
//-----------------------------------------------------------------------------
VOID Render()
{
    // Clear the backbuffer to a black color
    g_pd3dDevice->Clear( 0, NULL, D3DCLEAR_TARGET, D3DCOLOR_XRGB(0,0,0), 1.0f, 0 );
 
    // Begin the scene
    if( SUCCEEDED( g_pd3dDevice->BeginScene() ) )
    {
        // Setup the world, view, and projection matrices
  // 월드, 뷰, 프로젝션 행렬을 설정한다
        SetupMatrices();
  // 속도 최적화를 생각한다면 SetupMatrices()를 BeginScene()전에 먼저 호출하는게 더 효율적
  // BeginScene()과 EndScene() 함수 사이는 짧고 간결할 수록 좋다.

        // Render the vertex buffer contents
        g_pd3dDevice->SetStreamSource( 0, g_pVB, 0, sizeof(CUSTOMVERTEX) );
        g_pd3dDevice->SetFVF( D3DFVF_CUSTOMVERTEX );
        g_pd3dDevice->DrawPrimitive( D3DPT_TRIANGLESTRIP, 0, 1 );

        // End the scene
        g_pd3dDevice->EndScene();
    }

    // Present the backbuffer contents to the display
    g_pd3dDevice->Present( NULL, NULL, NULL, NULL );
}

 

//-----------------------------------------------------------------------------
// Name: MsgProc()
// Desc: The window's message handler
//-----------------------------------------------------------------------------
LRESULT WINAPI MsgProc( HWND hWnd, UINT msg, WPARAM wParam, LPARAM lParam )
{
    switch( msg )
    {
        case WM_DESTROY:
            Cleanup();
            PostQuitMessage( 0 );
            return 0;
    }

    return DefWindowProc( hWnd, msg, wParam, lParam );
}

 

//-----------------------------------------------------------------------------
// Name: WinMain()
// Desc: The application's entry point
//-----------------------------------------------------------------------------
INT WINAPI WinMain( HINSTANCE hInst, HINSTANCE, LPSTR, INT )
{
    // Register the window class
    WNDCLASSEX wc = { sizeof(WNDCLASSEX), CS_CLASSDC, MsgProc, 0L, 0L,
                      GetModuleHandle(NULL), NULL, NULL, NULL, NULL,
                      "D3D Tutorial", NULL };
    RegisterClassEx( &wc );

    // Create the application's window
    HWND hWnd = CreateWindow( "D3D Tutorial", "D3D Tutorial 03: Matrices",
                              WS_OVERLAPPEDWINDOW, 100, 100, 256, 256,
                              GetDesktopWindow(), NULL, wc.hInstance, NULL );

    // Initialize Direct3D
    if( SUCCEEDED( InitD3D( hWnd ) ) )
    {
        // Create the scene geometry
        if( SUCCEEDED( InitGeometry() ) )
        {
            // Show the window
            ShowWindow( hWnd, SW_SHOWDEFAULT );
            UpdateWindow( hWnd );

            // Enter the message loop
            MSG msg;
            ZeroMemory( &msg, sizeof(msg) );
            while( msg.message!=WM_QUIT )
            {
                if( PeekMessage( &msg, NULL, 0U, 0U, PM_REMOVE ) )
                {
                    TranslateMessage( &msg );
                    DispatchMessage( &msg );
                }
                else
                    Render();
            }
        }
    }

    UnregisterClass( "D3D Tutorial", wc.hInstance );
    return 0;
}