6. D3DXMatrixOrthoLH +正交投影矩阵

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

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

#define WINDOW_CLASS    "UGPDX"
#define WINDOW_NAME     "Ortho Projection 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_ortho;

// 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()
{
    // 生成正交投影矩阵
    //正交投影中，投影向量和观察平面垂直，物体坐标沿观察坐标系的z轴平行投影到观察平面上，
    //观察点和观察平面间的距离不会影响物体的投影大小
    //对于正交投影来说，它的取景范围是一个长方体，只有在这个长方体中的景物才会被绘制出来。
    // Set the projection matrix.
    D3DXMatrixOrthoLH(&g_ortho, WINDOW_WIDTH, WINDOW_HEIGHT, 0.1f, 1000.0f);
    g_D3DDevice->SetTransform(D3DTS_PROJECTION, &g_ortho);

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

    //代表是否绘制三角形的反面。
    // D3DCULL_MODE是背面隐藏消除的意思. 
    //SetRenderState( D3DRS_CULLMODE, D3DCULL_NONE )则正反面都绘制。 
    //SetRenderState( D3DRS_CULLMODE, D3DCULL_CW ); //绘制顺时针三角形。 
    //SetRenderState( D3DRS_CULLMODE, D3DCULL_CCW )绘制逆时针三角形。
    g_D3DDevice->SetRenderState(D3DRS_CULLMODE, D3DCULL_NONE);

    // Fill in our structure to draw an object.
    // x, y, z, color.
    stD3DVertex objData[] =
    {
        {-150.0f, -150.0f, 0.1f, D3DCOLOR_XRGB(255,0,0)},
        {150.0f, -150.0f, 0.1f, D3DCOLOR_XRGB(0,255,0)},
        {0.0f, 150.0f, 0.1f, 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();

    // Bind data to the stream, set fvf so D3D knows how our data
    // is made up, then render 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();
}