网格模型高级技术（7）

增强网格模型是运行镶嵌技术将原始网格模型的三角形面进行细分，形成更加精细（三角形面更多）的网格模型，这对于逐顶点进行的光照效果会更好。网格模型镶嵌技术主要用在层次细节场景中当模型距离观察者较近时，使模型的显示更精细。

增强网格模型可以通过对原始网格模型进行镶嵌细分模型得到，Direct3D提供了功能函数D3DXTessellateNPatches()来完成这一工作。该函数根据指定的参数，由显卡的镶嵌器（tessellator）对网格模型中的多边形进行细分，从而使原来的三维物体表面变得更加光滑细致。该函数声明如下：

Tessellates the given mesh using the N-patch tessellation scheme.

HRESULT D3DXTessellateNPatches(
  LPD3DXMESH pMeshIn,
  CONST DWORD * pAdjacencyIn,
  FLOAT NumSegs,
  BOOL QuadraticInterpNormals,
  LPD3DXMESH * ppMeshOut,
  LPD3DXBUFFER * ppAdjacencyOut
);

Parameters

pMeshIn: [in] Pointer to an ID3DXMesh interface, representing the mesh to tessellate.
pAdjacencyIn: [in] Pointer to an array of three DWORDs per face that specify the three neighbors for each face in the source mesh. This parameter may be NULL.
NumSegs: [in] Number of segments per edge to tessellate.
QuadraticInterpNormals: [in] Set to TRUE to use quadratic interpolation for normals; set to FALSE for linear interpolation.
ppMeshOut: [out] Address of a pointer to an ID3DXMesh interface, representing the returned tessellated mesh.
ppAdjacencyOut: [out] Address of a pointer to an ID3DXBuffer interface. If the value of this parameter is not set to NULL, this buffer will contain an array of three DWORDs per face that specify the three neighbors for each face in the output mesh. This parameter may be NULL.

Return Values

If the function succeeds, the return value is D3D_OK. If the function fails, the return value can be one of the following values: D3DERR_INVALIDCALL, D3DXERR_INVALIDDATA, E_OUTOFMEMORY.

Remarks

This function tessellates by using the N-patch algorithm.

在示例程序EnhancedMesh中，生成增强网格模型的代码如下：

//--------------------------------------------------------------------------------------
// Generate enhanced mesh from original mesh
//--------------------------------------------------------------------------------------
HRESULT GenerateEnhancedMesh(IDirect3DDevice9* device, UINT num_segs)
{
	ID3DXMesh*	enhanced_mesh;
	ID3DXMesh*	cloned_mesh;
	HRESULT		hr;

	// use 32 bit index to avoid vertex indices buffer overflow
	V_RETURN(g_mesh->CloneMeshFVF(D3DXMESH_MANAGED | D3DXMESH_32BIT, g_mesh->GetFVF(), device, &cloned_mesh));

	V_RETURN(D3DXTessellateNPatches(cloned_mesh, (DWORD*) g_adj_buffer->GetBufferPointer(), (float) num_segs,
									FALSE, &enhanced_mesh, NULL));

	release_com(cloned_mesh);
	release_com(g_enhanced_mesh);	// release already used global enhanced mesh

	g_enhanced_mesh = enhanced_mesh;

	return S_OK;
}

在上面的代码中，首先调用函数CloneMeshFVF()在原网格模型基础上进行克隆，这是因为后面将要生成的增强网格模型的顶点和多边形数量相当大，16位索引可能很难满足需求，为了防止意外，使用标志D3DXMESH_32BIT克隆出使用32位索引的新网格模型。接下来调用函数D3DXTessellateNPatches()生成增强网格模型。

运行效果图：

细分前

每边细分为2

每边细分为10

主程序：

#include "dxstdafx.h"
#include "resource.h"

#pragma warning(disable : 4127 4995)

#define IDC_TOGGLE_FULLSCREEN    1
#define IDC_TOGGLE_REF            2
#define IDC_CHANGE_DEVICE        3
#define IDC_SEGMENT                4

#define release_com(p)    do { if(p) { (p)->Release(); (p) = NULL; } } while(0)

ID3DXFont*                    g_font;
ID3DXSprite*                g_text_sprite;
bool                        g_show_help;

CDXUTDialogResourceManager    g_dlg_resource_manager;
CD3DSettingsDlg                g_settings_dlg;
CDXUTDialog                    g_button_dlg;
CDXUTDialog                    g_ui_dlg;

ID3DXMesh*                    g_mesh;
D3DMATERIAL9*                g_mesh_materials;
IDirect3DTexture9**            g_mesh_textures;
DWORD                        g_num_materials;
ID3DXBuffer*                g_adj_buffer;
ID3DXMesh*                    g_enhanced_mesh;
UINT                        g_num_segs = 1;

//--------------------------------------------------------------------------------------
// Rejects any devices that aren't acceptable by returning false
//--------------------------------------------------------------------------------------
bool CALLBACK IsDeviceAcceptable( D3DCAPS9* pCaps, D3DFORMAT AdapterFormat,
                                  D3DFORMAT BackBufferFormat, bool bWindowed, void* pUserContext )
{
    // Typically want to skip backbuffer formats that don't support alpha blending

    IDirect3D9* pD3D = DXUTGetD3DObject();

    if( FAILED( pD3D->CheckDeviceFormat( pCaps->AdapterOrdinal, pCaps->DeviceType, AdapterFormat,
                    D3DUSAGE_QUERY_POSTPIXELSHADER_BLENDING, D3DRTYPE_TEXTURE, BackBufferFormat ) ) )
        return false;

    return true;
}

//--------------------------------------------------------------------------------------
// Before a device is created, modify the device settings as needed.
//--------------------------------------------------------------------------------------
bool CALLBACK ModifyDeviceSettings( DXUTDeviceSettings* pDeviceSettings, const D3DCAPS9* pCaps, void* pUserContext )
{
    // If video card does not support hardware vertex processing, then uses sofaware vertex processing.
    if((pCaps->DevCaps & D3DDEVCAPS_HWTRANSFORMANDLIGHT) == 0)
        pDeviceSettings->BehaviorFlags = D3DCREATE_SOFTWARE_VERTEXPROCESSING;

    static bool is_first_time = true;

    if(is_first_time)
    {
        is_first_time = false;

        // if using reference device, then pop a warning message box.
        if(pDeviceSettings->DeviceType == D3DDEVTYPE_REF)
            DXUTDisplaySwitchingToREFWarning();
    }

    return true;
}

//--------------------------------------------------------------------------------------
// Remove path from fullname, and convert filename from multibyte to wchar.
//--------------------------------------------------------------------------------------
void RemovePathFromFileName(LPSTR fullname, LPWSTR wfilename)
{
    WCHAR wbuf[MAX_PATH]  = {0};
    MultiByteToWideChar(CP_ACP, 0, fullname, -1, wbuf, MAX_PATH);

    LPWSTR w_last_back_slash = wcsrchr(wbuf, '\\');

    if(w_last_back_slash)
        lstrcpy(wfilename, ++w_last_back_slash);
    else
        lstrcpy(wfilename, wbuf);
}

//--------------------------------------------------------------------------------------
// Generate enhanced mesh from original mesh
//--------------------------------------------------------------------------------------
HRESULT GenerateEnhancedMesh(IDirect3DDevice9* device, UINT num_segs)
{
    ID3DXMesh*    enhanced_mesh;
    ID3DXMesh*    cloned_mesh;
    HRESULT        hr;

    // use 32 bit index to avoid vertex indices buffer overflow
    V_RETURN(g_mesh->CloneMeshFVF(D3DXMESH_MANAGED | D3DXMESH_32BIT, g_mesh->GetFVF(), device, &cloned_mesh));

    V_RETURN(D3DXTessellateNPatches(cloned_mesh, (DWORD*) g_adj_buffer->GetBufferPointer(), (float) num_segs,
                                    FALSE, &enhanced_mesh, NULL));

    release_com(cloned_mesh);
    release_com(g_enhanced_mesh);    // release already used global enhanced mesh

    g_enhanced_mesh = enhanced_mesh;

    return S_OK;
}

//--------------------------------------------------------------------------------------
// Create any D3DPOOL_MANAGED resources here
//--------------------------------------------------------------------------------------
HRESULT CALLBACK OnCreateDevice( IDirect3DDevice9* pd3dDevice,
                                 const D3DSURFACE_DESC* pBackBufferSurfaceDesc,
                                 void* pUserContext )
{
    HRESULT    hr;

    V_RETURN(g_dlg_resource_manager.OnCreateDevice(pd3dDevice));
    V_RETURN(g_settings_dlg.OnCreateDevice(pd3dDevice));

    D3DXCreateFont(pd3dDevice, 18, 0, FW_BOLD, 1, FALSE, DEFAULT_CHARSET, OUT_DEFAULT_PRECIS, DEFAULT_QUALITY,
                   DEFAULT_PITCH | FF_DONTCARE, L"Arial", &g_font);

    ID3DXBuffer* material_buffer;

    V_RETURN(D3DXLoadMeshFromXW(L"cube.x", D3DXMESH_MANAGED, pd3dDevice, &g_adj_buffer, &material_buffer, NULL,
                                &g_num_materials, &g_mesh));

    D3DXMATERIAL* xmaterials = (D3DXMATERIAL*) material_buffer->GetBufferPointer();
    g_mesh_materials = new D3DMATERIAL9[g_num_materials];
    g_mesh_textures  = new IDirect3DTexture9*[g_num_materials];

    for(DWORD i = 0; i < g_num_materials; i++)
    {
        g_mesh_materials[i] = xmaterials[i].MatD3D;
        g_mesh_materials[i].Ambient = g_mesh_materials[i].Diffuse;

        WCHAR wfilename[256];
        RemovePathFromFileName(xmaterials[i].pTextureFilename, wfilename);

        g_mesh_textures[i] = NULL;

        if(xmaterials[i].pTextureFilename != NULL && lstrlen(wfilename) > 0)
        {
            V_RETURN(D3DXCreateTextureFromFileW(pd3dDevice, wfilename, &g_mesh_textures[i]));
        }
    }

    material_buffer->Release();

    V_RETURN(GenerateEnhancedMesh(pd3dDevice, g_num_segs));

    return S_OK;
}

//--------------------------------------------------------------------------------------
// Create any D3DPOOL_DEFAULT resources here
//--------------------------------------------------------------------------------------
HRESULT CALLBACK OnResetDevice( IDirect3DDevice9* pd3dDevice,
                                const D3DSURFACE_DESC* pBackBufferSurfaceDesc,
                                void* pUserContext )
{
    HRESULT hr;

    V_RETURN(g_dlg_resource_manager.OnResetDevice());
    V_RETURN(g_settings_dlg.OnResetDevice());
    V_RETURN(g_font->OnResetDevice());
    V_RETURN(D3DXCreateSprite(pd3dDevice, &g_text_sprite));

    // set dialog position and size

    g_button_dlg.SetLocation(pBackBufferSurfaceDesc->Width - 170, 0);
    g_button_dlg.SetSize(170, 170);

    g_ui_dlg.SetLocation(0, pBackBufferSurfaceDesc->Height - 60);
    g_ui_dlg.SetSize(pBackBufferSurfaceDesc->Width, 50);
    g_ui_dlg.GetControl(IDC_SEGMENT)->SetSize(pBackBufferSurfaceDesc->Width - 20, 16);

    // setup view matrix

    D3DXMATRIX mat_view;
    D3DXVECTOR3 eye(0.0f, 0.0f,  6.0f);
    D3DXVECTOR3  at(0.0f, 0.0f,  0.0f);
    D3DXVECTOR3  up(0.0f, 1.0f,  0.0f);

    D3DXMatrixLookAtLH(&mat_view, &eye, &at, &up);
    pd3dDevice->SetTransform(D3DTS_VIEW, &mat_view);

    // set projection matrix
    D3DXMATRIX mat_proj;
    float aspect = (float)pBackBufferSurfaceDesc->Width / pBackBufferSurfaceDesc->Height;
    D3DXMatrixPerspectiveFovLH(&mat_proj, D3DX_PI/4, aspect, 1.0f, 100.0f);
    pd3dDevice->SetTransform(D3DTS_PROJECTION, &mat_proj);

    return S_OK;
}

//--------------------------------------------------------------------------------------
// Release resources created in the OnResetDevice callback here
//--------------------------------------------------------------------------------------
void CALLBACK OnLostDevice( void* pUserContext )
{
    g_dlg_resource_manager.OnLostDevice();
    g_settings_dlg.OnLostDevice();
    g_font->OnLostDevice();

    release_com(g_text_sprite);
}

//--------------------------------------------------------------------------------------
// Release resources created in the OnCreateDevice callback here
//--------------------------------------------------------------------------------------
void CALLBACK OnDestroyDevice( void* pUserContext )
{
    g_dlg_resource_manager.OnDestroyDevice();
    g_settings_dlg.OnDestroyDevice();

    delete[] g_mesh_materials;
    g_mesh_materials = NULL;

    if(g_mesh_textures)
    {
        for(DWORD i = 0; i < g_num_materials; i++)
            release_com(g_mesh_textures[i]);

        delete[] g_mesh_textures;
        g_mesh_textures = NULL;
    }

    release_com(g_font);
    release_com(g_adj_buffer);
    release_com(g_mesh);
    release_com(g_enhanced_mesh);
}

//--------------------------------------------------------------------------------------
// Handle updates to the scene
//--------------------------------------------------------------------------------------
void CALLBACK OnFrameMove( IDirect3DDevice9* pd3dDevice, double fTime, float fElapsedTime, void* pUserContext )
{
    D3DXMATRIX mat_world;
    float time = timeGetTime() / 1000.0f;
    D3DXMatrixRotationYawPitchRoll(&mat_world, time, time, time);

    pd3dDevice->SetTransform(D3DTS_WORLD, &mat_world);
}

//--------------------------------------------------------------------------------------
// Render the helper information
//--------------------------------------------------------------------------------------
void RenderText()
{
    CDXUTTextHelper text_helper(g_font, g_text_sprite, 20);

    text_helper.Begin();

    // show frame and device states
    text_helper.SetInsertionPos(5, 5);
    text_helper.SetForegroundColor( D3DXCOLOR(1.0f, 0.475f, 0.0f, 1.0f) );
    text_helper.DrawTextLine( DXUTGetFrameStats(true) );
    text_helper.DrawTextLine( DXUTGetDeviceStats() );

    // show other simple information
    text_helper.SetForegroundColor( D3DXCOLOR(1.0f, 1.0f, 1.0f, 1.0f) );
    text_helper.DrawFormattedTextLine(L"Divide every edge of original mesh into part: %d\n", g_num_segs);
    text_helper.DrawFormattedTextLine(L"Enhanced mesh's faces number: %d\n", g_enhanced_mesh->GetNumFaces());
    text_helper.DrawFormattedTextLine(L"Enhanced mesh's vertices number: %d\n", g_enhanced_mesh->GetNumVertices());

    // show helper information

    const D3DSURFACE_DESC* surface_desc = DXUTGetBackBufferSurfaceDesc();

    if(g_show_help)
    {
        text_helper.SetInsertionPos(10, surface_desc->Height - 15 * 6);
        text_helper.SetForegroundColor( D3DXCOLOR(1.0f, 0.475f, 0.0f, 1.0f) );
        text_helper.DrawTextLine(L"Controls (F1 to hide):");

        text_helper.SetInsertionPos(40, surface_desc->Height - 15 * 4);
        text_helper.DrawTextLine(L"Quit: ESC");
    }
    else
    {
        text_helper.SetInsertionPos(10, surface_desc->Height - 15 * 4);
        text_helper.SetForegroundColor( D3DXCOLOR(1.0f, 1.0f, 1.0f, 1.0f) );
        text_helper.DrawTextLine(L"Press F1 for help");
    }

    text_helper.End();
}

//--------------------------------------------------------------------------------------
// Render the scene
//--------------------------------------------------------------------------------------
void CALLBACK OnFrameRender( IDirect3DDevice9* pd3dDevice, double fTime, float fElapsedTime, void* pUserContext )
{
    HRESULT hr;

    if(g_settings_dlg.IsActive())
    {
        g_settings_dlg.OnRender(fElapsedTime);
        return;
    }

    // Clear the render target and the zbuffer
    V( pd3dDevice->Clear(0, NULL, D3DCLEAR_TARGET | D3DCLEAR_ZBUFFER, D3DCOLOR_ARGB(0, 0, 92, 92), 1.0f, 0) );

    // Render the scene
    if( SUCCEEDED( pd3dDevice->BeginScene() ) )
    {
        for(DWORD i = 0; i < g_num_materials; i++)
        {
            pd3dDevice->SetMaterial(&g_mesh_materials[i]);
            pd3dDevice->SetTexture(0, g_mesh_textures[i]);
            g_enhanced_mesh->DrawSubset(i);
        }

        RenderText();
        V(g_button_dlg.OnRender(fElapsedTime));
        V(g_ui_dlg.OnRender(fElapsedTime));

        V( pd3dDevice->EndScene() );
    }
}

//--------------------------------------------------------------------------------------
// Handle messages to the application
//--------------------------------------------------------------------------------------
LRESULT CALLBACK MsgProc( HWND hWnd, UINT uMsg, WPARAM wParam, LPARAM lParam,
                          bool* pbNoFurtherProcessing, void* pUserContext )
{
    *pbNoFurtherProcessing = g_dlg_resource_manager.MsgProc(hWnd, uMsg, wParam, lParam);
    if(*pbNoFurtherProcessing)
        return 0;

    if(g_settings_dlg.IsActive())
    {
        g_settings_dlg.MsgProc(hWnd, uMsg, wParam, lParam);
        return 0;
    }

    *pbNoFurtherProcessing = g_button_dlg.MsgProc(hWnd, uMsg, wParam, lParam);
    if(*pbNoFurtherProcessing)
        return 0;

    *pbNoFurtherProcessing = g_ui_dlg.MsgProc(hWnd, uMsg, wParam, lParam);
    if(*pbNoFurtherProcessing)
        return 0;

    return 0;
}

//--------------------------------------------------------------------------------------
// Handle keybaord event
//--------------------------------------------------------------------------------------
void CALLBACK OnKeyboardProc(UINT charater, bool is_key_down, bool is_alt_down, void* user_context)
{
    if(is_key_down)
    {
        switch(charater)
        {
        case VK_F1:
            g_show_help = !g_show_help;
            break;
        }
    }
}

//--------------------------------------------------------------------------------------
// Handle events for controls
//--------------------------------------------------------------------------------------
void CALLBACK OnGUIEvent(UINT event, int control_id, CDXUTControl* control, void* user_context)
{
    switch(control_id)
    {
    case IDC_TOGGLE_FULLSCREEN:
        DXUTToggleFullScreen();
        break;

    case IDC_TOGGLE_REF:
        DXUTToggleREF();
        break;

    case IDC_CHANGE_DEVICE:
        g_settings_dlg.SetActive(true);
        break;

    case IDC_SEGMENT:
        g_num_segs = ((CDXUTSlider*) control)->GetValue();
        GenerateEnhancedMesh(DXUTGetD3DDevice(), g_num_segs);
        break;
    }
}

//--------------------------------------------------------------------------------------
// Initialize dialogs
//--------------------------------------------------------------------------------------
void InitDialogs()
{
    g_settings_dlg.Init(&g_dlg_resource_manager);
    g_button_dlg.Init(&g_dlg_resource_manager);
    g_ui_dlg.Init(&g_dlg_resource_manager);

    g_button_dlg.SetCallback(OnGUIEvent);

    int x = 35, y = 10, width = 125, height = 22;

    g_button_dlg.AddButton(IDC_TOGGLE_FULLSCREEN, L"Toggle full screen", x, y,         width, height);
    g_button_dlg.AddButton(IDC_TOGGLE_REF,          L"Toggle REF (F3)",     x, y += 24, width, height);
    g_button_dlg.AddButton(IDC_CHANGE_DEVICE,      L"Change device (F2)", x, y += 24, width, height, VK_F2);

    g_ui_dlg.SetCallback(OnGUIEvent);
    g_ui_dlg.AddSlider(IDC_SEGMENT, 10, 36, 150, 24, 1, 10, 1);
}

//--------------------------------------------------------------------------------------
// Initialize everything and go into a render loop
//--------------------------------------------------------------------------------------
INT WINAPI WinMain( HINSTANCE, HINSTANCE, LPSTR, int )
{
    // Enable run-time memory check for debug builds.
#if defined(DEBUG) | defined(_DEBUG)
    _CrtSetDbgFlag( _CRTDBG_ALLOC_MEM_DF | _CRTDBG_LEAK_CHECK_DF );
#endif

    // Set the callback functions
    DXUTSetCallbackDeviceCreated( OnCreateDevice );
    DXUTSetCallbackDeviceReset( OnResetDevice );
    DXUTSetCallbackDeviceLost( OnLostDevice );
    DXUTSetCallbackDeviceDestroyed( OnDestroyDevice );
    DXUTSetCallbackMsgProc( MsgProc );
    DXUTSetCallbackFrameRender( OnFrameRender );
    DXUTSetCallbackFrameMove( OnFrameMove );
    DXUTSetCallbackKeyboard(OnKeyboardProc);

    // TODO: Perform any application-level initialization here
    InitDialogs();

    // Initialize DXUT and create the desired Win32 window and Direct3D device for the application
    DXUTInit( true, true, true ); // Parse the command line, handle the default hotkeys, and show msgboxes
    DXUTSetCursorSettings( true, true ); // Show the cursor and clip it when in full screen
    DXUTCreateWindow( L"EnhancedMesh" );
    DXUTCreateDevice( D3DADAPTER_DEFAULT, true, 640, 480, IsDeviceAcceptable, ModifyDeviceSettings );

    // Start the render loop
    DXUTMainLoop();

    // TODO: Perform any application-level cleanup here

    return DXUTGetExitCode();
}

下载示例工程

posted on 2008-05-28 09:33 lovedday 阅读(1233) 评论(0) 编辑收藏引用

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