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outdated: 37.Cel-Shading

卡通人物的贴图及阴影实现。

在抗锯齿方面,OpenGL中只需glEnable(GL_LINE_SMOOTH)。

对于一个向量的旋转,直接乘以旋转矩阵可以得出。下面为代码,

void RotateVector(MATRIX &M, VECTOR &V, VECTOR &D)            // Rotate a vector{    D.X = M.Data[0] * V.X + M.Data[4] * V.Y + M.Data[8] * V.Z;    // Rotate round the x axis    D.Y = M.Data[1] * V.X + M.Data[5] * V.Y + M.Data[9] * V.Z;    // Rotate round the y axis    D.Z = M.Data[2] * V.X + M.Data[6] * V.Y + M.Data[10] * V.Z;   // Rotate round the z axis}

灯光设置为Z轴正方向(0,0,1),然后计算其法向量normal,接着再和旋转后的向量来个点积得到shade值。若小于零,就设置为零。这个shade值可以作为一维贴图坐标。

对于边框线条,首先得开启glEnable(GL_BLEND),然后设置blend mode即glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA),接着glPolygonMode(GL_BACK, GL_LINE)画反面多边形,最后是深度缓存glDepthFunc(GL_LEQUAL)。

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下面为代码,

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#ifndef GL_FRAMEWORK_INCLUDED#define GL_FRAMEWORK_INCLUDED#include <windows.h>typedef struct {                                   // Structure for keyboard stuff    BOOL keyDown[256];} Keys;typedef struct {                                   // Contains information vital to applications     HMODULE hInstance;                             // Application Instance    const char* className;} Application;typedef struct {                                   // Window creation info    Application* application;    char* title;    int width;    int height;    int bitsPerPixel;    BOOL isFullScreen;} GL_WindowInit;typedef struct {                                   // Contains information vital to a window    Keys* keys;    HWND hWnd;                                     // Windows handle    HDC hDC;                                       // Device context    HGLRC hRC;                                     // Rendering context    GL_WindowInit init;    BOOL isVisible;                                // Window visiable?    DWORD lastTickCount;                           // Tick counter} GL_Window;void TerminateApplication(GL_Window* window);      // Terminate the applicationvoid ToggleFullscreen(GL_Window* window);          // Toggle fullscreen / Windowed modeBOOL Initialize(GL_Window* window, Keys* keys);void Deinitialize(void);void Update(DWORD milliseconds);void Draw(void);#endif
Previous.h
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#include <Windows.h>#include <GL\glew.h>#include <GL\glut.h>#include "Previous.h"#define WM_TOGGLEFULLSCREEN (WM_USER+1)                   // Application define message for toggling // between fulscreen / windowed modestatic BOOL g_isProgramLooping;                           // Window creation loop, for fullscreen / windowed modestatic BOOL g_createFullScreen;                           // If true, then create windowvoid TerminateApplication(GL_Window* window)              // Terminate the application{    PostMessage(window->hWnd, WM_QUIT, 0, 0);             // Send a WM_QUIT message    g_isProgramLooping = FALSE;                           // Stop looping of the program}void ToggleFullscreen(GL_Window* window)                  // Toggle fullscreen /windowed mode{    PostMessage(window->hWnd, WM_TOGGLEFULLSCREEN, 0, 0); // Send a WM_TOGGLEFULLSCREEN message}void ReshapeGL(int width, int height)                     // Reshape the window  when it‘s moved or resized{    glViewport(0, 0, (GLsizei)(width), (GLsizei)(height)); // Reset the current viewport    glMatrixMode(GL_PROJECTION);    glLoadIdentity();    // Calcutate the aspect ratio of the window    gluPerspective(45.0f, (GLfloat)(width) / (GLfloat)(height), 1.0, 100.0f);    glMatrixMode(GL_MODELVIEW);    glLoadIdentity();}BOOL ChangeScreenResolution(int width, int height, int bitsPerPixel)     // Change the screen resolution{    DEVMODE dmScreenSettings;                              // Device mode    ZeroMemory(&dmScreenSettings, sizeof(DEVMODE));        // Make sure memory is cleared    dmScreenSettings.dmSize = sizeof(DEVMODE);             // Size of the devmode structure    dmScreenSettings.dmPelsWidth = width;    dmScreenSettings.dmPelsHeight = height;    dmScreenSettings.dmBitsPerPel = bitsPerPixel;    dmScreenSettings.dmFields = DM_BITSPERPEL | DM_PELSWIDTH | DM_PELSHEIGHT;    if (ChangeDisplaySettings(&dmScreenSettings, CDS_FULLSCREEN) != DISP_CHANGE_SUCCESSFUL) {        return FALSE;                                      // Display change failed    }    return TRUE;}BOOL CreateWindowGL(GL_Window* window){    DWORD windowStyle = WS_OVERLAPPEDWINDOW;                // Define window style    DWORD windowExtendedStyle = WS_EX_APPWINDOW;            // Define the window‘s extended style    PIXELFORMATDESCRIPTOR pdf = {        sizeof(PIXELFORMATDESCRIPTOR),                      // Size of this pixel format descriptor        1,                                                  // Version Number        PFD_DRAW_TO_WINDOW |                                // Format must support window        PFD_SUPPORT_OPENGL |                                // Format must support openGL        PFD_DOUBLEBUFFER,                                   // Must support double buffering        PFD_TYPE_RGBA,                                      // Request an RGBA format        window->init.bitsPerPixel,                          // Select color depth        0, 0, 0, 0, 0, 0,                                   // Color bits ignored        0,                                                  // No alpha buffer        0,                                                  // Shift bit ignored        0,                                                  // No accumulation buffer        0, 0, 0, 0,                                         // Accumulation bits ignored        16,                                                 // 16bits Z-buffer (depth buffer)        0,                                                  // No stencil buffer        0,                                                  // No auxiliary buffer        PFD_MAIN_PLANE,                                     // Main drawing layer        0,                                                  // Reserved        0, 0, 0                                             // Layer masks ignored    };    RECT windowRect = { 0, 0, window->init.width, window->init.height };   // Window coordiantes    GLuint PixelFormat;    if (window->init.isFullScreen == TRUE) {        if (ChangeScreenResolution(window->init.width, window->init.height, window->init.bitsPerPixel) == FALSE)        {            // Fullscreen mode failed, run in windowed mode instead            MessageBox(HWND_DESKTOP, "Mode Switch Failed.\nRuning In Windowed Mode.",                "Error", MB_OK | MB_ICONEXCLAMATION);            window->init.isFullScreen = FALSE;        }        else {            ShowCursor(FALSE);            windowStyle = WS_POPUP;                         // Popup window            windowExtendedStyle |= WS_EX_TOPMOST;        }    }    else {        // Adjust window, account for window borders        AdjustWindowRectEx(&windowRect, windowStyle, 0, windowExtendedStyle);    }    // Create Opengl window    window->hWnd = CreateWindowEx(windowExtendedStyle,      // Extended style        window->init.application->className,                // Class name        window->init.title,                                 // Window title        windowStyle,                                        // Window style        0, 0,                                               // Window X,Y position        windowRect.right - windowRect.left,                 // Window width        windowRect.bottom - windowRect.top,                 // Window height        HWND_DESKTOP,                                       // Desktop is window‘s parent        0,                                                  // No menu        window->init.application->hInstance,                // Pass the window instance        window);    if (window->hWnd == 0) {                                // Was window creation a success?        return FALSE;    }    window->hDC = GetDC(window->hWnd);    if (window->hDC == 0) {        DestroyWindow(window->hWnd);        window->hWnd = 0;        return FALSE;    }    PixelFormat = ChoosePixelFormat(window->hDC, &pdf);     // Find a compatible pixel format    if (PixelFormat == 0) {        ReleaseDC(window->hWnd, window->hDC);               // Release device context        window->hDC = 0;        DestroyWindow(window->hWnd);        window->hWnd = 0;        return FALSE;    }    if (SetPixelFormat(window->hDC, PixelFormat, &pdf) == FALSE) {   // Try to set the pixel format        ReleaseDC(window->hWnd, window->hDC);        window->hDC = 0;        DestroyWindow(window->hWnd);        window->hWnd = 0;        return FALSE;    }    window->hRC = wglCreateContext(window->hDC);            // Try to get a rendering context    if (window->hRC == 0) {        ReleaseDC(window->hWnd, window->hDC);        window->hDC = 0;        DestroyWindow(window->hWnd);        window->hWnd = 0;        return FALSE;    }    // Make the rendering context our current rendering context    if (wglMakeCurrent(window->hDC, window->hRC) == FALSE) {        wglDeleteContext(window->hRC);                      //  Delete the rendering context        window->hRC = 0;        ReleaseDC(window->hWnd, window->hDC);        window->hDC = 0;        DestroyWindow(window->hWnd);        window->hWnd = 0;        return FALSE;    }    ShowWindow(window->hWnd, SW_NORMAL);                    // Make the window visiable    window->isVisible = TRUE;    ReshapeGL(window->init.width, window->init.height);     // Reshape our GL window    ZeroMemory(window->keys, sizeof(Keys));                 // Clear all keys    window->lastTickCount = GetTickCount();    return TRUE;}BOOL DestoryWindowGL(GL_Window* window){    if (window->hWnd != 0) {        if (window->hDC != 0) {            wglMakeCurrent(window->hDC, 0);                 // Setting current active rendering context to zero            if (window->hRC != 0) {                wglDeleteContext(window->hRC);                window->hRC = 0;            }            ReleaseDC(window->hWnd, window->hDC);            window->hDC = 0;        }        DestroyWindow(window->hWnd);        window->hWnd = 0;    }    if (window->init.isFullScreen) {        ChangeDisplaySettings(NULL, 0);                     // Switch back to desktop resolution        ShowCursor(TRUE);    }    return TRUE;}// Process window message callbackLRESULT CALLBACK WindowProc(HWND hWnd, UINT uMsg, WPARAM wParam, LPARAM lParam){    // Get the window context    GL_Window* window = (GL_Window*)(GetWindowLong(hWnd, GWL_USERDATA));    switch (uMsg) {                                         // Evaluate window message    case WM_SYSCOMMAND:                                     // Intercept system commands    {        switch (wParam) {                                   // Check system calls        case SC_SCREENSAVE:                                 // Screensaver trying to start?        case SC_MONITORPOWER:                               // Mointer trying to enter powersave?            return 0;                                           // Prevent form happening        }        break;    }    return 0;    case WM_CREATE:    {        CREATESTRUCT* creation = (CREATESTRUCT*)(lParam);   // Store window structure pointer        window = (GL_Window*)(creation->lpCreateParams);        SetWindowLong(hWnd, GWL_USERDATA, (LONG)(window));    }    return 0;    case WM_CLOSE:        TerminateApplication(window);        return 0;    case WM_SIZE:        switch (wParam) {        case SIZE_MINIMIZED:                                 // Was window minimized?            window->isVisible = FALSE;            return 0;        case SIZE_MAXIMIZED:            window->isVisible = TRUE;            ReshapeGL(LOWORD(lParam), HIWORD(lParam));            return 0;        case SIZE_RESTORED:            window->isVisible = TRUE;            ReshapeGL(LOWORD(lParam), HIWORD(lParam));            return 0;        }        break;    case WM_KEYDOWN:        if ((wParam >= 0) && (wParam <= 255)) {            window->keys->keyDown[wParam] = TRUE;            // Set the selected key(wParam) to true            return 0;        }        break;    case WM_KEYUP:        if ((wParam >= 0) && (wParam <= 255)) {            window->keys->keyDown[wParam] = FALSE;            return 0;        }        break;    case WM_TOGGLEFULLSCREEN:        g_createFullScreen = (g_createFullScreen == TRUE) ? FALSE : TRUE;        PostMessage(hWnd, WM_QUIT, 0, 0);        break;    }    return DefWindowProc(hWnd, uMsg, wParam, lParam);        // Pass unhandle message to DefWindowProc}BOOL RegisterWindowClass(Application* application){    WNDCLASSEX windowClass;    ZeroMemory(&windowClass, sizeof(WNDCLASSEX));            // Make sure memory is cleared    windowClass.cbSize = sizeof(WNDCLASSEX);                 // Size of the windowClass structure    windowClass.style = CS_HREDRAW | CS_VREDRAW | CS_OWNDC;  // Redraws the window for any movement / resizing    windowClass.lpfnWndProc = (WNDPROC)(WindowProc);         // WindowProc handles message    windowClass.hInstance = application->hInstance;          // Set the instance    windowClass.hbrBackground = (HBRUSH)(COLOR_APPWORKSPACE);// Class background brush color    windowClass.hCursor = LoadCursor(NULL, IDC_ARROW);       // Load the arrow pointer    windowClass.lpszClassName = application->className;      // Sets the application className    if (RegisterClassEx(&windowClass) == 0) {        MessageBox(HWND_DESKTOP, "RegisterClassEx Failed!", "Error", MB_OK | MB_ICONEXCLAMATION);        return FALSE;    }    return TRUE;}int WINAPI WinMain(HINSTANCE hIstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nCmdShow){    Application application;    GL_Window window;    Keys keys;    BOOL isMessagePumpActive;    MSG msg;    DWORD tickCount;    application.className = "OpenGL";    application.hInstance = hIstance;    ZeroMemory(&window, sizeof(GL_Window));    window.keys = &keys;                                     // Window key structure    window.init.application = &application;                  // Window application    window.init.title = "Cel-Shading";                       // Window title    window.init.width = 640;                                 // Window width    window.init.height = 480;                                // Window height    window.init.bitsPerPixel = 16;                           // Bits per pixel    window.init.isFullScreen = TRUE;                         // Fullscreen? (set to TRUE)    ZeroMemory(&keys, sizeof(Keys));    if (MessageBox(HWND_DESKTOP, "Would You Like To Run In Fullscreen Mode?", "Start FullScreen?",        MB_YESNO | MB_ICONQUESTION) == IDNO)    {        window.init.isFullScreen = FALSE;    }    if (RegisterWindowClass(&application) == FALSE)    {        MessageBox(HWND_DESKTOP, "Error Registering Window Class!", "Error", MB_OK | MB_ICONEXCLAMATION);        return -1;    }    g_isProgramLooping = TRUE;    g_createFullScreen = window.init.isFullScreen;    while (g_isProgramLooping) {                             // Loop until WM_QUIT is received        window.init.isFullScreen = g_createFullScreen;       // Set init param of window creation to fullscreen?        if (CreateWindowGL(&window) == TRUE) {               // Was window creation successful?                                                             // At this point we should have a window that is setup to render OpenGL            if (Initialize(&window, &keys) == FALSE) {                TerminateApplication(&window);               // Close window, this will handle the shutdown            }            else {                isMessagePumpActive = TRUE;                while (isMessagePumpActive == TRUE) {                    // Success creating window. Check for window messages                    if (PeekMessage(&msg, window.hWnd, 0, 0, PM_REMOVE) != 0) {                        if (msg.message != WM_QUIT) {                            DispatchMessage(&msg);                        }                        else {                            isMessagePumpActive = FALSE;     // Terminate the message pump                        }                    }                    else {                        if (window.isVisible == FALSE) {                            WaitMessage();                   // Application is minimized wait for a message                        }                        else {                            // Process application loop                            tickCount = GetTickCount();      // Get the tick count                            Update(tickCount - window.lastTickCount); // Update the counter                            window.lastTickCount = tickCount;// Set last count to current count                            Draw();                          // Draw screen                            SwapBuffers(window.hDC);                        }                    }                }            }            // Application is finished            Deinitialize();            DestoryWindowGL(&window);        }        else {            MessageBox(HWND_DESKTOP, "Error Creating OpenGL Window", "Error", MB_OK | MB_ICONEXCLAMATION);            g_isProgramLooping = FALSE;        }    }    UnregisterClass(application.className, application.hInstance);    // UnRegister window class    return 0;}
Previous.cpp
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#include <Windows.h>#include <GL/glew.h>#include <GL/glut.h>#include <GL/GLUAX.H>#include <math.h>#include <stdio.h>#include "Previous.h"#pragma comment(lib, "legacy_stdio_definitions.lib")#ifndef CDS_FULLSCREEN#define CDS_FULLSCREEN 4#endifGL_Window* g_window;Keys* g_keys;typedef struct tagMATRIX {    float Data[16];                  // Matrix format} MATRIX;typedef struct tagVECTOR {    float X, Y, Z;} VECTOR;typedef struct tagVERTEX {    VECTOR Nor;                      // Normal    VECTOR Pos;                      // Position} VERTEX;typedef struct tagPOLYGON {          // Polygon    VERTEX Verts[3];} POLYGON;bool outlineDraw = true;             // Flag to draw the outlinebool outlineSmooth = false;          // Flag to Anti-Alias the linesfloat outlineColor[3] = { 0.0f, 0.0f, 0.0f };     // Color of the linefloat outlineWidth = 3.0f;           // Width of the linesVECTOR lightAngle;                   // The direction of the lightbool lightRotate = false;            // Flag to see if rotate the lightfloat modelAngle = 0.0f;             // Y-axis angle of the modelbool modelRotate = false;            // Flag to rotate the modelPOLYGON* polyData = http://www.mamicode.com/NULL;            // Polygon dataint polyNum = 0;                     // Number of polygonGLuint shaderTexture[1];             // Storage for one textureBOOL ReadMesh(){    FILE* In = fopen("Data/model.txt", "rb");    if (!In) {        return FALSE;    }    fread(&polyNum, sizeof(int), 1, In);    // Read the header (number of polygon)    polyData = http://www.mamicode.com/(POLYGON*)malloc(sizeof(POLYGON) * polyNum);    fread(&polyData[0], sizeof(POLYGON) * polyNum, 1, In);    fclose(In);    return TRUE;}inline float DotProduct(VECTOR &V1, VECTOR &V2){    return V1.X * V2.X + V1.Y * V2.Y + V1.Z * V2.Z;}inline float Magnitude(VECTOR &V)                    // The length of the vector{    return sqrt(V.X * V.X + V.Y * V.Y + V.Z * V.Z);}void Normalize(VECTOR &V)                            // Create a vector with a unit length of 1{    float M = Magnitude(V);    if (M != 0.0f) {        V.X /= M;        V.Y /= M;        V.Z /= M;    }}void RotateVector(MATRIX &M, VECTOR &V, VECTOR &D)            // Rotate a vector{    D.X = M.Data[0] * V.X + M.Data[4] * V.Y + M.Data[8] * V.Z;    // Rotate round the x axis    D.Y = M.Data[1] * V.X + M.Data[5] * V.Y + M.Data[9] * V.Z;    // Rotate round the y axis    D.Z = M.Data[2] * V.X + M.Data[6] * V.Y + M.Data[10] * V.Z;   // Rotate round the z axis}BOOL Initialize(GL_Window* window, Keys* keys){    char Line[255];    float shaderData[32][3];    FILE *In = NULL;    g_window = window;    g_keys = keys;    glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST);     // Realy nice perspective calculations    glClearColor(0.1f, 0.1f, 0.1f, 0.0f);    glClearDepth(1.0f);        glEnable(GL_DEPTH_TEST);    glDepthFunc(GL_LESS);    glShadeModel(GL_SMOOTH);    glDisable(GL_LINE_SMOOTH);    glEnable(GL_CULL_FACE);    glDisable(GL_LIGHTING);    In = fopen("Data/shader.txt", "r");    if (In) {        for (int i = 0; i < 32; i++) {            if (feof(In)) break;            fgets(Line, 255, In);            shaderData[i][0] = shaderData[i][1] = shaderData[i][2] = float(atof(Line));        }        fclose(In);    }    else {        return FALSE;    }    glGenTextures(1, &shaderTexture[0]);    glBindTexture(GL_TEXTURE_1D, shaderTexture[0]);    glTexParameteri(GL_TEXTURE_1D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);    glTexParameteri(GL_TEXTURE_1D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);    glTexImage1D(GL_TEXTURE_1D, 0, GL_RGB, 32, 0, GL_RGB, GL_FLOAT, shaderData);    lightAngle.X = 0.0f;    lightAngle.Y = 0.0f;    lightAngle.Z = 1.0f;    Normalize(lightAngle);    return ReadMesh();}void Deinitialize(void){    glDeleteTextures(1, &shaderTexture[0]);    free(polyData);}void Update(DWORD milliseconds){    if (g_keys->keyDown[ ] == TRUE) {        modelRotate = !modelRotate;                  // Toggle model rotation        g_keys->keyDown[ ] = FALSE;    }    if (g_keys->keyDown[1] == TRUE) {        outlineDraw = !outlineDraw;                  // Tpggle outline drawing        g_keys->keyDown[1] = FALSE;    }    if (g_keys->keyDown[2] == TRUE) {        outlineSmooth = !outlineSmooth;              // Toggle Anti-Aliasing        g_keys->keyDown[2] = FALSE;    }    if (g_keys->keyDown[VK_UP] == TRUE) {        outlineWidth++;                              // Line width        g_keys->keyDown[VK_UP] = FALSE;    }    if (g_keys->keyDown[VK_DOWN] == TRUE) {        outlineWidth--;                              // Line width        g_keys->keyDown[VK_DOWN] = FALSE;    }    if (modelRotate) {        modelAngle += (float)(milliseconds) / 10.0f;    }}void Draw(){    float TmpShade;                // Temporary shader value    MATRIX TmpMatrix;    VECTOR TmpVector, TmpNormal;    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);    glLoadIdentity();    if (outlineSmooth) {           // Check        glHint(GL_LINE_SMOOTH_HINT, GL_NICEST);        glEnable(GL_LINE_SMOOTH);                // Enable Anti-Aliasing    }    else {        glDisable(GL_LINE_SMOOTH);    }    glTranslatef(0.0f, 0.0f, -2.0f);    glRotatef(modelAngle, 0.0f, 1.0f, 0.0f);    glGetFloatv(GL_MODELVIEW_MATRIX, TmpMatrix.Data);      // Get the generatef matrix    // Cel-shading code    glEnable(GL_TEXTURE_1D);    glBindTexture(GL_TEXTURE_1D, shaderTexture[0]);    glColor3f(0.8f, 0.2f, 0.2f);    glBegin(GL_TRIANGLES);    for (int i = 0; i < polyNum; ++i) {        for (int j = 0; j < 3; ++j) {            TmpNormal.X = polyData[i].Verts[j].Nor.X;            TmpNormal.Y = polyData[i].Verts[j].Nor.Y;            TmpNormal.Z = polyData[i].Verts[j].Nor.Z;            RotateVector(TmpMatrix, TmpNormal, TmpVector);     // Rotate            Normalize(TmpVector);                        TmpShade = DotProduct(TmpVector, lightAngle);            if (TmpShade < 0.0f) {                TmpShade = 0.0f;            }            glTexCoord1f(TmpShade);          // Set the texture coordinate as the shade value            glVertex3fv(&polyData[i].Verts[j].Pos.X);        }    }    glEnd();    glDisable(GL_TEXTURE_1D);    if (outlineDraw) {             // Check        glEnable(GL_BLEND);        glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);   // Blend mode        glPolygonMode(GL_BACK, GL_LINE);           // Draw backfacing polygon as wireframes        glLineWidth(outlineWidth);        glCullFace(GL_FRONT);                      // Don‘t draw any front-face polygon        glDepthFunc(GL_LEQUAL);        glColor3fv(&outlineColor[0]);              // Set the outline color        glBegin(GL_TRIANGLES);        for (int i = 0; i < polyNum; ++i) {            for (int j = 0; j < 3; ++j) {                glVertex3fv(&polyData[i].Verts[j].Pos.X);            }        }        glEnd();        glDepthFunc(GL_LESS);               // Reset        glCullFace(GL_BACK);                // Reset        glPolygonMode(GL_BACK, GL_FILL);    // Reset        glDisable(GL_BLEND);    }}
Main.cpp

Thanks for Nehe‘s tutorials, this is his home.

outdated: 37.Cel-Shading