8. 世界矩阵使物体移动

#include<d3d9.h>
#include<d3dx9.h>

#pragma comment(lib, "d3d9.lib")
#pragma comment(lib, "d3dx9.lib")

#define WINDOW_CLASS    "UGPDX"
#define WINDOW_NAME     "World Matrix"
#define WINDOW_WIDTH    640
#define WINDOW_HEIGHT   480

// Function Prototypes...
bool InitializeD3D(HWND hWnd, bool fullscreen);
bool InitializeObjects();
void RenderScene();
void Shutdown();


// Direct3D object and device.
LPDIRECT3D9 g_D3D = NULL;
LPDIRECT3DDEVICE9 g_D3DDevice = NULL;

D3DXMATRIX g_projection;
D3DXMATRIX g_worldMatrix;
D3DXMATRIX g_translation;
D3DXMATRIX g_rotation;

float g_angle = 0.0f;

// Vertex buffer to hold the geometry.
LPDIRECT3DVERTEXBUFFER9 g_VertexBuffer = NULL;

// A structure for our custom vertex type
struct stD3DVertex
{
    float x, y, z;
    unsigned long color;
};

// Our custom FVF, which describes our custom vertex structure
#define D3DFVF_VERTEX (D3DFVF_XYZ | D3DFVF_DIFFUSE)


LRESULT WINAPI MsgProc(HWND hWnd, UINT msg, WPARAM wParam, LPARAM lParam)
{
    switch(msg)
    {
    case WM_DESTROY:
        PostQuitMessage(0);
        return 0;
        break;

    case WM_KEYUP:
        if(wParam == VK_ESCAPE) PostQuitMessage(0);
        break;
    }

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


int WINAPI WinMain(HINSTANCE hInst, HINSTANCE prevhInst, LPSTR cmdLine, int show)
{
    // Register the window class
    WNDCLASSEX wc = { sizeof(WNDCLASSEX), CS_CLASSDC, MsgProc, 0L, 0L,
        GetModuleHandle(NULL), NULL, NULL, NULL, NULL,
        WINDOW_CLASS, NULL };
    RegisterClassEx(&wc);

    // Create the application's window
    HWND hWnd = CreateWindow(WINDOW_CLASS, WINDOW_NAME, WS_OVERLAPPEDWINDOW,
        100, 100, WINDOW_WIDTH, WINDOW_HEIGHT, GetDesktopWindow(),
        NULL, wc.hInstance, NULL);

    // Initialize Direct3D
    if(InitializeD3D(hWnd, false))
    {
        // 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
                RenderScene();
        }
    }

    // Release any and all resources.
    Shutdown();

    // Unregister our window.
    UnregisterClass(WINDOW_CLASS, wc.hInstance);
    return 0;
}


bool InitializeD3D(HWND hWnd, bool fullscreen)
{
    D3DDISPLAYMODE displayMode;

    // Create the D3D object.
    g_D3D = Direct3DCreate9(D3D_SDK_VERSION);
    if(g_D3D == NULL) return false;

    // Get the desktop display mode.
    if(FAILED(g_D3D->GetAdapterDisplayMode(D3DADAPTER_DEFAULT, &displayMode)))
        return false;

    // Set up the structure used to create the D3DDevice
    D3DPRESENT_PARAMETERS d3dpp;
    ZeroMemory(&d3dpp, sizeof(d3dpp));

    if(fullscreen)
    {
        d3dpp.Windowed = FALSE;
        d3dpp.BackBufferWidth = WINDOW_WIDTH;
        d3dpp.BackBufferHeight = WINDOW_HEIGHT;
    }
    else
        d3dpp.Windowed = TRUE;
    d3dpp.SwapEffect = D3DSWAPEFFECT_DISCARD;
    d3dpp.BackBufferFormat = displayMode.Format;

    // Create the D3DDevice
    if(FAILED(g_D3D->CreateDevice(D3DADAPTER_DEFAULT, D3DDEVTYPE_HAL, hWnd,
        D3DCREATE_SOFTWARE_VERTEXPROCESSING, &d3dpp, &g_D3DDevice)))
    {
        return false;
    }

    // Initialize any objects we will be displaying.
    if(!InitializeObjects()) return false;

    return true;
}


bool InitializeObjects()
{
    // Set the projection matrix.
    D3DXMatrixPerspectiveFovLH(&g_projection, D3DX_PI / 4,
        WINDOW_WIDTH/WINDOW_HEIGHT, 0.1f, 1000.0f);

    g_D3DDevice->SetTransform(D3DTS_PROJECTION, &g_projection);

    // Set default rendering states.
    g_D3DDevice->SetRenderState(D3DRS_LIGHTING, FALSE);
    g_D3DDevice->SetRenderState(D3DRS_CULLMODE, D3DCULL_NONE);

    // Fill in our structure to draw an object.
    // x, y, z, color.
    stD3DVertex objData[] =
    {
        {-0.3f, -0.3f, 1.0f, D3DCOLOR_XRGB(255,255,0)},
        {0.3f, -0.3f, 1.0f, D3DCOLOR_XRGB(255,0,0)},
        {0.0f, 0.3f, 1.0f, D3DCOLOR_XRGB(0,0,255)}
    };

    // Create the vertex buffer.
    if(FAILED(g_D3DDevice->CreateVertexBuffer(3 * sizeof(stD3DVertex), 0,
        D3DFVF_VERTEX, D3DPOOL_DEFAULT, &g_VertexBuffer, NULL))) return false;

    // Fill the vertex buffer.
    void *ptr;
    if(FAILED(g_VertexBuffer->Lock(0, sizeof(objData), (void**)&ptr, 0))) return false;
    memcpy(ptr, objData, sizeof(objData));
    g_VertexBuffer->Unlock();

    return true;
}


void RenderScene()
{
    // Clear the backbuffer.
    g_D3DDevice->Clear(0, NULL, D3DCLEAR_TARGET, D3DCOLOR_XRGB(0,0,0), 1.0f, 0);

    // Begin the scene.  Start rendering.
    g_D3DDevice->BeginScene();

    // Build translation and rotation matrices.
    // 要使物体移动就需要每帧改变世界矩阵
    // 所以将世界矩阵放到这里来设置，透视投影矩阵每帧都保持不变所以在前面一次性设置好
    // 物体在世界坐标系中的初始位置是（0,0,0）即物体的初始世界坐标为（0,0,0），下面的平移矩阵将物体
    // 移动到（0,0,3.0）。
    // 平移旋转的实现：每一帧绘制的时候都将物体位置移到（0,0,3.0），然后开始绕Y轴旋转
    // 一定的角度，由于每一帧的角度大小是逐渐变大的，所以是每一帧都从一个相同的位置开始
    // 旋转，每帧旋转的度数逐渐变大，看上去旋转
    D3DXMatrixTranslation(&g_translation, 0.0f, 0.0f, 3.0f);
    D3DXMatrixRotationY(&g_rotation, g_angle);

    // Build the world matrix and update angle.
    g_worldMatrix = g_rotation * g_translation;
    g_angle += 0.01f;
    if(g_angle >= 360) g_angle = 0.0f;

    // Set the world matrix.
    g_D3DDevice->SetTransform(D3DTS_WORLD, &g_worldMatrix);

    // Draw the object.
    g_D3DDevice->SetStreamSource(0, g_VertexBuffer, 0, sizeof(stD3DVertex));
    g_D3DDevice->SetFVF(D3DFVF_VERTEX);
    g_D3DDevice->DrawPrimitive(D3DPT_TRIANGLELIST, 0, 1);

    // End the scene.  Stop rendering.
    g_D3DDevice->EndScene();

    // Display the scene.
    g_D3DDevice->Present(NULL, NULL, NULL, NULL);
}


void Shutdown()
{
    if(g_D3DDevice != NULL) g_D3DDevice->Release();
    if(g_D3D != NULL) g_D3D->Release();
    if(g_VertexBuffer != NULL) g_VertexBuffer->Release();

    g_D3DDevice = NULL;
    g_D3D = NULL;
    g_VertexBuffer = NULL;
}
/*
在游戏编程中使物体可以在场景中移动，这很重要。下面将介绍改变当前世界矩阵或模型矩阵的方法。
世界矩阵控制物体位置的参考点。开始时，起点位于(0,0)。通过指定要绘制的新几何图形集合的新起点，
改动世界矩阵，就可以在3D空间中四处移动。例如，使用如D3DXMatrixTranslation()这样的函数就可以改变
世界位置。D3DXMatrixTranslation()函数的参数包括创建不同于D3DXMATRIX类型的世界矩阵的矩阵、要移动世
界矩阵的X、Y和Z的值。如果要将新的世界矩阵位置从(0,0,0)设置为(0,0,-5)，那么只要使用程序清单1.23中
的几行代码即可。
D3DXMATRIX world;
D3DXMatrixRotationY(&world, 30.0f);
g_D3DDevice->SetTransform(D3DTS_WORLD, &g_world);
*/