[DX Tutorial] Lesson 7: Simple Modeling

1. Building a Quad
Quad라 함은 4각형을 말하는데 아래의 3개는 모두 4각형이다.

Image 7.1 - Various Quads

앞서서 말했다 시피 사실 모든 물체는 삼각형으로 구성이 되는데 바로 다음 그림처럼 구성이 된다.

Image 7.2 - Quads Are Dual Triangles

자 그렇다면 주된 질문인 어떻게 그것을 만들어 내느냐에 대한 대답은... 살펴보자꾸나. 이전 프로그램에서 만든 삼각형 대신 이번에는 4각형을 만들어 볼것이다.

// this is the function that puts the 3D models into video RAM
void init_graphics(void)
{
    // create the vertices using the CUSTOMVERTEX struct
    CUSTOMVERTEX t_vert[] =
    {
        { -3.0f, 3.0f, 0.0f, D3DCOLOR_XRGB(0, 0, 255), },
        { 3.0f, 3.0f, 0.0f, D3DCOLOR_XRGB(0, 255, 0), },
        { -3.0f, -3.0f, 0.0f, D3DCOLOR_XRGB(255, 0, 0), },
        { 3.0f, -3.0f, 0.0f, D3DCOLOR_XRGB(0, 255, 255), },
    };

    // create a vertex buffer interface called t_buffer
    d3ddev->CreateVertexBuffer(4*sizeof(CUSTOMVERTEX),    // change to 4, instead of 3
                               0,
                               CUSTOMFVF,
                               D3DPOOL_MANAGED,
                               &t_buffer,
                               NULL);

    VOID* pVoid;    // a void pointer

    // lock t_buffer and load the vertices into it
    t_buffer->Lock(0, 0, (void**)&pVoid, 0);
    memcpy(pVoid, t_vert, sizeof(t_vert));
    t_buffer->Unlock();

    return;
}

바뀐 부분을 보면 다만 점이 4개라는 것뿐, 그리고 VertexBuffer 사이즈가 하나 더 늘었다는 것 외에는 없다. 이제 바꿔줘야 할 중요한 부분이 있는데 바로 2개의 삼각형을 이용해서 사각형을 구성하라는 명령인 다음 명령이다.

d3ddev->SetStreamSource(0, t_buffer, 0, sizeof(CUSTOMVERTEX));

d3ddev->DrawPrimitive(D3DPT_TRIANGLESTRIP, 0, 2);

보시다시피 바뀐 부분은 아래쪽 명령인데 첫 인자가 D3DPT_TRIANGLESTRIP으로 바뀌어 있다. 이것은 이전에 들어가 있던 인자인 D3DPT_TRIANGLELIST에서 바뀐 것으로 삼각형의 strip으로 구성하겠다는 의미이며 마지막 숫자인 2가 몇개의 strip이 들어가는지를 말해준다.

다음 그림이 간단한 설명을 해주는데 매우 간략하고 보기도 좋다.

Image 7.3 - Making Triangles

2. Combining Quads To Make a Cube
이제 요 사각형들을 조합해서 Cube를 만들어보자.

// create the vertices using the CUSTOMVERTEX struct
CUSTOMVERTEX t_vert[] =
{
    // side 1
    { -3.0f, 3.0f, -3.0f, D3DCOLOR_XRGB(0, 0, 255), },
    { 3.0f, 3.0f, -3.0f, D3DCOLOR_XRGB(0, 255, 0), },
    { -3.0f, -3.0f, -3.0f, D3DCOLOR_XRGB(255, 0, 0), },
    { 3.0f, -3.0f, -3.0f, D3DCOLOR_XRGB(0, 255, 255), },

    // side 2
    { -3.0f, 3.0f, 3.0f, D3DCOLOR_XRGB(0, 0, 255), },
    { -3.0f, -3.0f, 3.0f, D3DCOLOR_XRGB(0, 255, 0), },
    { 3.0f, 3.0f, 3.0f, D3DCOLOR_XRGB(255, 0, 0), },
    { 3.0f, -3.0f, 3.0f, D3DCOLOR_XRGB(0, 255, 255), },

    // side 3
    { -3.0f, 3.0f, 3.0f, D3DCOLOR_XRGB(0, 0, 255), },
    { 3.0f, 3.0f, 3.0f, D3DCOLOR_XRGB(0, 255, 0), },
    { -3.0f, 3.0f, -3.0f, D3DCOLOR_XRGB(255, 0, 0), },
    { 3.0f, 3.0f, -3.0f, D3DCOLOR_XRGB(0, 255, 255), },

    // side 4
    { -3.0f, -3.0f, 3.0f, D3DCOLOR_XRGB(0, 0, 255), },
    { -3.0f, -3.0f, -3.0f, D3DCOLOR_XRGB(0, 255, 0), },
    { 3.0f, -3.0f, 3.0f, D3DCOLOR_XRGB(255, 0, 0), },
    { 3.0f, -3.0f, -3.0f, D3DCOLOR_XRGB(0, 255, 255), },

    // side 5
    { 3.0f, 3.0f, -3.0f, D3DCOLOR_XRGB(0, 0, 255), },
    { 3.0f, 3.0f, 3.0f, D3DCOLOR_XRGB(0, 255, 0), },
    { 3.0f, -3.0f, -3.0f, D3DCOLOR_XRGB(255, 0, 0), },
    { 3.0f, -3.0f, 3.0f, D3DCOLOR_XRGB(0, 255, 255), },

    // side 6
    { -3.0f, 3.0f, -3.0f, D3DCOLOR_XRGB(0, 0, 255), },
    { -3.0f, -3.0f, -3.0f, D3DCOLOR_XRGB(0, 255, 0), },
    { -3.0f, 3.0f, 3.0f, D3DCOLOR_XRGB(255, 0, 0), },
    { -3.0f, -3.0f, 3.0f, D3DCOLOR_XRGB(0, 255, 255), },
};

// create a vertex buffer interface called t_buffer
d3ddev->CreateVertexBuffer(24*sizeof(CUSTOMVERTEX),
                           0,
                           CUSTOMFVF,
                           D3DPOOL_MANAGED,
                           &t_buffer,
                           NULL);

생각보다 복잡시럽다. 이것은 OpenGL에서도 마찬가지다. 상당히 번거롭다. 이제 이걸 그려줘야 하는데 하나의 명령을 쓱싹 그려질줄 알았는데 아니다. 왜냐면 중복되는 점들이 있기 때문이라는데... 그래서 각 면을 2개의 삼각형으로 그려내라는 명령을 따로 따로 각각의 면에 대해서 (총 6개 면) 삼각형을 두개씩 그리라는 명령을 다음과 같이 주면 효율적이다.

d3ddev->SetStreamSource(0, t_buffer, 0, sizeof(CUSTOMVERTEX));

d3ddev->DrawPrimitive(D3DPT_TRIANGLESTRIP, 0, 2);
d3ddev->DrawPrimitive(D3DPT_TRIANGLESTRIP, 4, 2);
d3ddev->DrawPrimitive(D3DPT_TRIANGLESTRIP, 8, 2);
d3ddev->DrawPrimitive(D3DPT_TRIANGLESTRIP, 12, 2);
d3ddev->DrawPrimitive(D3DPT_TRIANGLESTRIP, 16, 2);
d3ddev->DrawPrimitive(D3DPT_TRIANGLESTRIP, 20, 2);

이 코드를 삽입해서 실행해 보면 다음과 같은 결과를 얻을수 있다.

Image 7.4 - A Rotating Cube

3. More Shapes
A Square Pyramid

Image 7.5 - A Square Pyramid

// create the vertices using the CUSTOMVERTEX
struct CUSTOMVERTEX t_vert[] =
{
    // base
    { -3.0f, 0.0f, 3.0f, D3DCOLOR_XRGB(0, 255, 0), },
    { -3.0f, 0.0f, -3.0f, D3DCOLOR_XRGB(255, 0, 0), },
    { 3.0f, 0.0f, 3.0f, D3DCOLOR_XRGB(0, 0, 255), },
    { 3.0f, 0.0f, -3.0f, D3DCOLOR_XRGB(0, 255, 255), },

    // triangle 1
    { -3.0f, 0.0f, 3.0f, D3DCOLOR_XRGB(0, 0, 255), },
    { 3.0f, 0.0f, 3.0f, D3DCOLOR_XRGB(255, 0, 0), },
    { 0.0f, 7.0f, 0.0f, D3DCOLOR_XRGB(0, 255, 0), },

    // triangle 2
    { 3.0f, 0.0f, 3.0f, D3DCOLOR_XRGB(0, 0, 255), },
    { 3.0f, 0.0f, -3.0f, D3DCOLOR_XRGB(255, 0, 0), },
    { 0.0f, 7.0f, 0.0f, D3DCOLOR_XRGB(0, 255, 0), },

    // triangle 3
    { 3.0f, 0.0f, -3.0f, D3DCOLOR_XRGB(0, 0, 255), },
    { -3.0f, 0.0f, -3.0f, D3DCOLOR_XRGB(255, 0, 0), },
    { 0.0f, 7.0f, 0.0f, D3DCOLOR_XRGB(0, 255, 0), },

    // triangle 4
    { -3.0f, 0.0f, -3.0f, D3DCOLOR_XRGB(0, 0, 255), },
    { -3.0f, 0.0f, 3.0f, D3DCOLOR_XRGB(255, 0, 0), },
    { 0.0f, 7.0f, 0.0f, D3DCOLOR_XRGB(0, 255, 0), },
};

// create a vertex buffer interface called t_buffer
d3ddev->CreateVertexBuffer(16*sizeof(CUSTOMVERTEX),
                           0,
                           CUSTOMFVF,
                           D3DPOOL_MANAGED,
                           &t_buffer,
                           NULL);

d3ddev->SetStreamSource(0, t_buffer, 0, sizeof(CUSTOMVERTEX));

d3ddev->DrawPrimitive(D3DPT_TRIANGLESTRIP, 0, 2);    // base
d3ddev->DrawPrimitive(D3DPT_TRIANGLESTRIP, 4, 1);    // triangle 1
d3ddev->DrawPrimitive(D3DPT_TRIANGLESTRIP, 7, 1);    // triangle 2
d3ddev->DrawPrimitive(D3DPT_TRIANGLESTRIP, 10, 1);    // triangle 3
d3ddev->DrawPrimitive(D3DPT_TRIANGLESTRIP, 13, 1);    // triangle 4

The Hypercraft

Image 7.6 - The Hypercraft

// create the vertices using the CUSTOMVERTEX
struct CUSTOMVERTEX t_vert[] =
{
    // fuselage
    { 3.0f, 0.0f, 0.0f, D3DCOLOR_XRGB(0, 255, 0), },
    { 0.0f, 3.0f, -3.0f, D3DCOLOR_XRGB(0, 0, 255), },
    { 0.0f, 0.0f, 10.0f, D3DCOLOR_XRGB(255, 0, 0), },
    { -3.0f, 0.0f, 0.0f, D3DCOLOR_XRGB(0, 255, 255), },

    // left gun
    { 3.2f, -1.0f, -3.0f, D3DCOLOR_XRGB(0, 0, 255), },
    { 3.2f, -1.0f, 11.0f, D3DCOLOR_XRGB(0, 255, 0), },
    { 2.0f, 1.0f, 2.0f, D3DCOLOR_XRGB(255, 0, 0), },

    // right gun
    { -3.2f, -1.0f, -3.0f, D3DCOLOR_XRGB(0, 0, 255), },
    { -3.2f, -1.0f, 11.0f, D3DCOLOR_XRGB(0, 255, 0), },
    { -2.0f, 1.0f, 2.0f, D3DCOLOR_XRGB(255, 0, 0), },

    // bottom of fuselage
    { 0.0f, 3.0f, -3.0f, D3DCOLOR_XRGB(0, 0, 255), },
    { 3.0f, 0.0f, 0.0f, D3DCOLOR_XRGB(0, 255, 0), },
    { -3.0f, 0.0f, 0.0f, D3DCOLOR_XRGB(0, 255, 255), },
    { 0.0f, 0.0f, 10.0f, D3DCOLOR_XRGB(255, 0, 0), },

    // opposite side of left gun
    { 3.2f, -1.0f, -3.0f, D3DCOLOR_XRGB(0, 0, 255), },
    { 2.0f, 1.0f, 2.0f, D3DCOLOR_XRGB(255, 0, 0), },
    { 3.2f, -1.0f, 11.0f, D3DCOLOR_XRGB(0, 255, 0), },

    // opposite side of right gun
    { -3.2f, -1.0f, -3.0f, D3DCOLOR_XRGB(0, 0, 255), },
    { -2.0f, 1.0f, 2.0f, D3DCOLOR_XRGB(255, 0, 0), },
    { -3.2f, -1.0f, 11.0f, D3DCOLOR_XRGB(0, 255, 0), },
};

// create a vertex buffer interface called t_buffer
d3ddev->CreateVertexBuffer(20*sizeof(CUSTOMVERTEX),
                                     0,
                                     CUSTOMFVF,
                                     D3DPOOL_MANAGED,
                                     &t_buffer,
                                     NULL);

d3ddev->SetStreamSource(0, t_buffer, 0, sizeof(CUSTOMVERTEX));

d3ddev->DrawPrimitive(D3DPT_TRIANGLESTRIP, 0, 2);    // fuselage
d3ddev->DrawPrimitive(D3DPT_TRIANGLESTRIP, 4, 1);    // left gun
d3ddev->DrawPrimitive(D3DPT_TRIANGLESTRIP, 7, 1);    // right gun
d3ddev->DrawPrimitive(D3DPT_TRIANGLESTRIP, 10, 2);    // bottom of fuselage
d3ddev->DrawPrimitive(D3DPT_TRIANGLESTRIP, 14, 1);    // other side of left gun
d3ddev->DrawPrimitive(D3DPT_TRIANGLESTRIP, 17, 1);    // other side of right gun

4. The Finished Program
완성된 코드를 보자... 간단하다.

// include the basic windows header files and the Direct3D header file
#include <windows.h>
#include <windowsx.h>
#include <d3d9.h>
#include <d3dx9.h>

// define the screen resolution and keyboard macros
#define SCREEN_WIDTH 640
#define SCREEN_HEIGHT 480
#define KEY_DOWN(vk_code) ((GetAsyncKeyState(vk_code) & 0x8000) ? 1 : 0)
#define KEY_UP(vk_code) ((GetAsyncKeyState(vk_code) & 0x8000) ? 0 : 1)

// include the Direct3D Library files
#pragma comment (lib, "d3d9.lib")
#pragma comment (lib, "d3dx9.lib")

// global declarations
LPDIRECT3D9 d3d;    // the pointer to our Direct3D interface
LPDIRECT3DDEVICE9 d3ddev;    // the pointer to the device class
LPDIRECT3DVERTEXBUFFER9 t_buffer = NULL;    // the pointer to the vertex buffer

// function prototypes
void initD3D(HWND hWnd);    // sets up and initializes Direct3D
void render_frame(void);    // renders a single frame
void cleanD3D(void);    // closes Direct3D and releases memory
void init_graphics(void);    // 3D declarations

struct CUSTOMVERTEX {FLOAT X, Y, Z; DWORD COLOR;};
#define CUSTOMFVF (D3DFVF_XYZ | D3DFVF_DIFFUSE)

// the WindowProc function prototype
LRESULT CALLBACK WindowProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam);


// the entry point for any Windows program
int WINAPI WinMain(HINSTANCE hInstance,
                   HINSTANCE hPrevInstance,
                   LPSTR lpCmdLine,
                   int nCmdShow)
{
    HWND hWnd;
    WNDCLASSEX wc;

    ZeroMemory(&wc, sizeof(WNDCLASSEX));

    wc.cbSize = sizeof(WNDCLASSEX);
    wc.style = CS_HREDRAW | CS_VREDRAW;
    wc.lpfnWndProc = (WNDPROC)WindowProc;
    wc.hInstance = hInstance;
    wc.hCursor = LoadCursor(NULL, IDC_ARROW);
    wc.lpszClassName = L"WindowClass";

    RegisterClassEx(&wc);

    hWnd = CreateWindowEx(NULL, L"WindowClass", L"Our Direct3D Program",
                          WS_EX_TOPMOST | WS_POPUP, 0, 0, SCREEN_WIDTH, SCREEN_HEIGHT,
                          NULL, NULL, hInstance, NULL);

    // set up and initialize Direct3D
    initD3D(hWnd);

    // enter the main loop:

    MSG msg;

    while(TRUE)
    {
        DWORD starting_point = GetTickCount();

        if (PeekMessage(&msg, NULL, 0, 0, PM_REMOVE))
        {
            if (msg.message == WM_QUIT)
                break;

            TranslateMessage(&msg);
            DispatchMessage(&msg);
        }

        render_frame();

        // check the 'escape' key
        if(KEY_DOWN(VK_ESCAPE))
            PostMessage(hWnd, WM_DESTROY, 0, 0);

        while ((GetTickCount() - starting_point) < 25);
    }

    // clean up DirectX and COM
    cleanD3D();

    return msg.wParam;
}


// this is the main message handler for the program
LRESULT CALLBACK WindowProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
    switch(message)
    {
        case WM_DESTROY:
            {
                PostQuitMessage(0);
                return 0;
            } break;
    }

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


// this function initializes and prepares Direct3D for use
void initD3D(HWND hWnd)
{
    d3d = Direct3DCreate9(D3D_SDK_VERSION);

    D3DPRESENT_PARAMETERS d3dpp;

    ZeroMemory(&d3dpp, sizeof(d3dpp));
    d3dpp.Windowed = FALSE;
    d3dpp.SwapEffect = D3DSWAPEFFECT_DISCARD;
    d3dpp.hDeviceWindow = hWnd;
    d3dpp.BackBufferFormat = D3DFMT_X8R8G8B8;
    d3dpp.BackBufferWidth = SCREEN_WIDTH;
    d3dpp.BackBufferHeight = SCREEN_HEIGHT;
    d3dpp.EnableAutoDepthStencil = TRUE;
    d3dpp.AutoDepthStencilFormat = D3DFMT_D16;

    // create a device class using this information and the info from the d3dpp stuct
    d3d->CreateDevice(D3DADAPTER_DEFAULT,
                      D3DDEVTYPE_HAL,
                      hWnd,
                      D3DCREATE_SOFTWARE_VERTEXPROCESSING,
                      &d3dpp,
                      &d3ddev);

    init_graphics();    // call the function to initialize the Hypercraft

    d3ddev->SetRenderState(D3DRS_LIGHTING, FALSE);    // turn off the 3D lighting
    d3ddev->SetRenderState(D3DRS_ZENABLE, TRUE);    // turn on the z-buffer

    return;
}


// this is the function used to render a single frame
void render_frame(void)
{
    d3ddev->Clear(0, NULL, D3DCLEAR_TARGET, D3DCOLOR_XRGB(0, 0, 0), 1.0f, 0);
    d3ddev->Clear(0, NULL, D3DCLEAR_ZBUFFER, D3DCOLOR_XRGB(0, 0, 0), 1.0f, 0);

    d3ddev->BeginScene();

    // select which vertex format we are using
    d3ddev->SetFVF(CUSTOMFVF);

    // set the view transform
    D3DXMATRIX matView;    // the view transform matrix
    D3DXMatrixLookAtLH(&matView,
    &D3DXVECTOR3 (0.0f, 8.0f, 25.0f),    // the camera position
    &D3DXVECTOR3 (0.0f, 0.0f, 0.0f),      // the look-at position
    &D3DXVECTOR3 (0.0f, 1.0f, 0.0f));    // the up direction
    d3ddev->SetTransform(D3DTS_VIEW, &matView);    // set the view transform to matView

    // set the projection transform
    D3DXMATRIX matProjection;    // the projection transform matrix
    D3DXMatrixPerspectiveFovLH(&matProjection,
                               D3DXToRadian(45),    // the horizontal field of view
                               (FLOAT)SCREEN_WIDTH / (FLOAT)SCREEN_HEIGHT, // aspect ratio
                               1.0f,   // the near view-plane
                               100.0f);    // the far view-plane
    d3ddev->SetTransform(D3DTS_PROJECTION, &matProjection); // set the projection

    // set the world transform
    static float index = 0.0f; index+=0.03f; // an ever-increasing float value
    D3DXMATRIX matRotateY;    // a matrix to store the rotation for each triangle
    D3DXMatrixRotationY(&matRotateY, index);    // the rotation matrix
    d3ddev->SetTransform(D3DTS_WORLD, &(matRotateY));    // set the world transform

    // select the vertex buffer to display
    d3ddev->SetStreamSource(0, t_buffer, 0, sizeof(CUSTOMVERTEX));

    // draw the Hypercraft
    d3ddev->DrawPrimitive(D3DPT_TRIANGLESTRIP, 0, 2);    // fuselage
    d3ddev->DrawPrimitive(D3DPT_TRIANGLESTRIP, 4, 1);    // left gun
    d3ddev->DrawPrimitive(D3DPT_TRIANGLESTRIP, 7, 1);    // right gun
    d3ddev->DrawPrimitive(D3DPT_TRIANGLESTRIP, 10, 2);    // bottom of fuselage
    d3ddev->DrawPrimitive(D3DPT_TRIANGLESTRIP, 14, 1);    // other side of left gun
    d3ddev->DrawPrimitive(D3DPT_TRIANGLESTRIP, 17, 1);    // other side of right gun

    d3ddev->EndScene();

    d3ddev->Present(NULL, NULL, NULL, NULL);

    return;
}


// this is the function that cleans up Direct3D and COM
void cleanD3D(void)
{
    t_buffer->Release();    // close and release the vertex buffer
    d3ddev->Release();    // close and release the 3D device
    d3d->Release();    // close and release Direct3D

    return;
}


// this is the function that puts the 3D models into video RAM
void init_graphics(void)
{
    // create the vertices using the CUSTOMVERTEX
    struct CUSTOMVERTEX t_vert[] =
    {
        // fuselage
        { 3.0f, 0.0f, 0.0f, D3DCOLOR_XRGB(0, 255, 0), },
        { 0.0f, 3.0f, -3.0f, D3DCOLOR_XRGB(0, 0, 255), },
        { 0.0f, 0.0f, 10.0f, D3DCOLOR_XRGB(255, 0, 0), },
        { -3.0f, 0.0f, 0.0f, D3DCOLOR_XRGB(0, 255, 255), },

        // left gun
        { 3.2f, -1.0f, -3.0f, D3DCOLOR_XRGB(0, 0, 255), },
        { 3.2f, -1.0f, 11.0f, D3DCOLOR_XRGB(0, 255, 0), },
        { 2.0f, 1.0f, 2.0f, D3DCOLOR_XRGB(255, 0, 0), },

        // right gun
        { -3.2f, -1.0f, -3.0f, D3DCOLOR_XRGB(0, 0, 255), },
        { -3.2f, -1.0f, 11.0f, D3DCOLOR_XRGB(0, 255, 0), },
        { -2.0f, 1.0f, 2.0f, D3DCOLOR_XRGB(255, 0, 0), },

        // bottom of fuselage
        { 0.0f, 3.0f, -3.0f, D3DCOLOR_XRGB(0, 0, 255), },
        { 3.0f, 0.0f, 0.0f, D3DCOLOR_XRGB(0, 255, 0), },
        { -3.0f, 0.0f, 0.0f, D3DCOLOR_XRGB(0, 255, 255), },
        { 0.0f, 0.0f, 10.0f, D3DCOLOR_XRGB(255, 0, 0), },

        // opposite side of left gun
        { 3.2f, -1.0f, -3.0f, D3DCOLOR_XRGB(0, 0, 255), },
        { 2.0f, 1.0f, 2.0f, D3DCOLOR_XRGB(255, 0, 0), },
        { 3.2f, -1.0f, 11.0f, D3DCOLOR_XRGB(0, 255, 0), },

        // opposite side of right gun
        { -3.2f, -1.0f, -3.0f, D3DCOLOR_XRGB(0, 0, 255), },
        { -2.0f, 1.0f, 2.0f, D3DCOLOR_XRGB(255, 0, 0), },
        { -3.2f, -1.0f, 11.0f, D3DCOLOR_XRGB(0, 255, 0), },
    };

    // create a vertex buffer interface called t_buffer
    d3ddev->CreateVertexBuffer(20*sizeof(CUSTOMVERTEX),
                               0,
                               CUSTOMFVF,
                               D3DPOOL_MANAGED,
                               &t_buffer,
                               NULL);

    VOID* pVoid;    // a void pointer

    // lock t_buffer and load the vertices into it
    t_buffer->Lock(0, 0, (void**)&pVoid, 0);
    memcpy(pVoid, t_vert, sizeof(t_vert));
    t_buffer->Unlock();

    return;
}