Assignment 4 OpenGL中正十二面体追踪球实现（平移、旋转、多面体线框体切换）

/*
 * 正十二面体追踪球，鼠标左键控制旋转，鼠标右键控制平移，鼠标中键打开菜单选择多面体或者线框体。
 * 键盘wsad或者↑↓←→控制平移，F1和F2键选择多面体或者线框体。 
**/

#include <math.h>
#include <GL/glut.h>

#ifndef M_PI
#define M_PI 3.1415926535898
#endif

//绘制多面体或者线框图的标识符
#define POLYHEDRAL 0
#define WIREFRAME 1

int winWidth, winHeight;//窗口的宽高

GLfloat angle = 0.0;//旋转角度累积值
GLfloat axis[] = {0.0, 0.0, 0.0};// 记录累计旋转后的坐标轴向量

bool trackingMouse = false;//跟踪鼠标是否有点击并移动
bool startLocate = true;//每次点击鼠标时开始定位

bool isRotate = false;//标识是否在进行旋转
bool isTranslate = false;//标识是否在进行平移

GLdouble viewer[] = {0.0, 0.0, 6.0};//用于设置视点位置gluLookAt()，参数要求为GLdouble

int curx, cury;// 记录当前鼠标坐标
GLfloat lastPos[3] = {0.0, 0.0, 0.0};// 记录鼠标上一次位置向量

// 正十二面体点的坐标
GLfloat vertices[][3] = {
    {1.214124, 0.000000, 1.589309},
    {0.375185, 1.154701, 1.589309},
    {-0.982247, 0.713644, 1.589309},
    {-0.982247, -0.713644, 1.589309},
    {0.375185, -1.154701, 1.589309},
    {1.964494, 0.000000, 0.375185},
    {0.607062, 1.868345, 0.375185},
    {-1.589309, 1.154701, 0.375185},
    {-1.589309, -1.154701, 0.375185},
    {0.607062, -1.868345, 0.375185},
    {1.589309, 1.154701, -0.375185},
    {-0.607062, 1.868345, -0.375185},
    {-1.964494, 0.000000, -0.375185},
    {-0.607062, -1.868345, -0.375185},
    {1.589309, -1.154701, -0.375185},
    {0.982247, 0.713644, -1.589309},
    {-0.375185, 1.154701, -1.589309},
    {-1.214124, 0.000000, -1.589309},
    {-0.375185, -1.154701, -1.589309},
    {0.982247, -0.713644, -1.589309}
};

// 正十二面体的颜色
// GLfloat colors[][3] = {
//     {0.8,0.2,0.2}, {1.0,0.0,0.0}, {1.0,1.0,0.0}, {0.0,1.0,0.0},
//     {0.0,0.0,0.5}, {1.0,0.0,1.0}, {1.0,1.0,1.0}, {0.0,1.0,1.0},
//     {0.0,0.0,1.0}, {1.0,0.5,1.0}, {0.5,0.5,0.5}, {0.0,0.5,0.5}
// };
GLfloat colors[][3] = {
    {1.0, 0.0, 0.0}, {0.0, 1.0, 0.0}, {0.0, 0.0, 1.0}, {1.0, 1.0, 0.0},
    {1.0, 0.0, 1.0}, {0.0, 1.0, 1.0}, {1.0, 1.0, 1.0}, {0.6, 0.6, 0.6},
    {0.6, 0.0, 0.0}, {0.0, 0.6, 0.0}, {0.0, 0.0, 0.6}, {0.6, 0.2, 0.2}
};

//根据顶点和颜色参数画出面
void polygon(int a, int b, int c, int d, int e, int f)
{
    glBegin(GL_POLYGON);
    glColor3fv(colors[a]);
    glVertex3fv(vertices[b]);
    glVertex3fv(vertices[c]);
    glVertex3fv(vertices[d]);
    glVertex3fv(vertices[e]);
    glVertex3fv(vertices[f]);
    glEnd();
}

//根据顶点索引参数画正十二面体，分十二个面画
void colorcube(void) {
    polygon(0, 0, 1, 2, 3, 4);
    polygon(1, 0, 5, 10, 6, 1);
    polygon(2, 1, 6, 11, 7, 2);
    polygon(3, 2, 7, 12, 8, 3);
    polygon(4, 3, 8, 13, 9, 4);
    polygon(5, 4, 9, 14, 5, 0);
    polygon(6, 15, 10, 5, 14, 19);
    polygon(7, 16, 11, 6, 10, 15);
    polygon(8, 17, 12, 7, 11, 16);
    polygon(9, 18, 13, 8, 12, 17);
    polygon(10, 19, 14, 9, 13, 18);
    polygon(11, 19, 18, 17, 16, 15);
}

void trackball_ptov(int x, int y, int width, int height, GLfloat v[3]) {
    GLfloat d, a;
    // 将x， y投影到在width，height内的半球中心
    v[0] = (2.0F * x - width) / width;
    v[1] = (height - 2.0F * y) / height;
    d = (GLfloat)sqrt(v[0] * v[0] + v[1] * v[1]);
    v[2] = (GLfloat)cos((M_PI / 2.0F) * ((d < 1.0F) ? d : 1.0F));
    a = 1.0F / (GLfloat)sqrt(v[0] * v[0] + v[1] * v[1] + v[2] * v[2]);
    v[0] *= a;
    v[1] *= a;
    v[2] *= a;
}

//记录旋转参数
void rotate(GLfloat curPos[3]) {
    GLfloat dx, dy, dz;
    dx = curPos[0] - lastPos[0];
    dy = curPos[1] - lastPos[1];
    dz = curPos[2] - lastPos[2];
    
    angle += 100.0f * sqrt(dx * dx + dy * dy + dz * dz);
    axis[0] += lastPos[1] * curPos[2] - lastPos[2] * curPos[1];
    axis[1] += lastPos[2] * curPos[0] - lastPos[0] * curPos[2];
    axis[2] += lastPos[0] * curPos[1] - lastPos[1] * curPos[0];
    
    lastPos[0] = curPos[0];
    lastPos[1] = curPos[1];
    lastPos[2] = curPos[2];
}

//记录平移位置
void translate(GLfloat x, GLfloat y) {
    GLfloat dx = 10.0 * (x - curx) / winWidth;
    GLfloat dy = 10.0 * (cury - y) / winHeight;
    
    //反向移动视点位置来实现物体平移
    viewer[0] -= dx;
    viewer[1] -= dy;
    
    curx = x;
    cury = y;
}

// 鼠标划动时回调函数
void mouseMotion(int x, int y) {
    GLfloat curPos[3];
    trackball_ptov(x, y, winWidth, winHeight, curPos);
    
    //若第一次点击，则重新定位初始坐标
    if (startLocate) {
        lastPos[0] = curPos[0];
        lastPos[1] = curPos[1];
        lastPos[2] = curPos[2];
        curx = x;
        cury = y;
        
        startLocate = false;
    }
    
    //跟踪鼠标
    if (trackingMouse) {
        if (isTranslate) {//跟踪平移
            translate(x, y);
        } else if (isRotate) {//跟踪旋转
            rotate(curPos);
        }
    }
    glutPostRedisplay();
}

// 开始跟踪旋转
void startRotation(int x, int y) {
    trackingMouse = true;
    trackball_ptov(x, y, winWidth, winHeight, lastPos);
    isRotate = true;
    startLocate = true;
}

// 停止跟踪旋转
void stopRotation(int x, int y) {
    trackingMouse = false;
}

// 开始跟踪平移
void startTranslation(int x, int y) {
    trackingMouse = true;
    trackball_ptov(x, y, winWidth, winHeight, lastPos);
    isTranslate = true;
    startLocate = true;
}

// 停止跟踪平移
void stopTranslation(int x, int y) {
    trackingMouse = false;
    isTranslate = false;
}

//处理左右鼠标按钮事件
void mouseButton(int btn, int state, int x, int y) {
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    
    if (btn == GLUT_LEFT_BUTTON) {// 左键则跟踪旋转
        switch (state) {
            case GLUT_DOWN:
                y = winHeight - y;
                startRotation(x, y);
                break;
            case GLUT_UP:
                stopRotation(x, y);
                break;
        }
    } else if (btn == GLUT_RIGHT_BUTTON) {//右键则跟踪平移
        switch (state) {
            case GLUT_DOWN:
                y = winHeight - y;
                startTranslation(x, y);
                break;
            case GLUT_UP:
                stopTranslation(x, y);
                break;
        }
    }
}

void myDisplay(void) {
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    
    // 重新加载原矩阵
    glLoadIdentity();
    
    // 设定视点位置、焦点，达到平移的效果
    gluLookAt(viewer[0], viewer[1], viewer[2],
              viewer[0], viewer[1], viewer[2] - 5,
              0.0, 1.0, 0.0);
    
    // 旋转
    if (isRotate) {
        glRotatef(angle, axis[0], axis[1], axis[2]);
    }
    
    colorcube();
    glFlush();
    glutSwapBuffers();
}

void myReshape(int w, int h) {
    glViewport(0, 0, w, h);
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    //透视投影
    gluPerspective(85.0, w/h, 4.0, 15.0);
    winWidth = w;
    winHeight = h;
    glMatrixMode(GL_MODELVIEW);
}

void myIdle() {
    glutPostRedisplay();
}

//处理按键函数wsad四个方向
void processKeys(unsigned char key, int x, int y) {
    switch (key) {
        case ‘w‘:
        case ‘W‘:
            viewer[1] -= 0.3;
            break;
        case ‘s‘:
        case ‘S‘:
            viewer[1] += 0.3;
            break;
        case ‘a‘:
        case ‘A‘:
            viewer[0] += 0.3;
            break;
        case ‘d‘:
        case ‘D‘:
            viewer[0] -= 0.3;
            break;
    }
    myDisplay();
}

//处理特殊按键上下左右四个方向
void processSpecialKeys(int key, int x, int y) {
    switch (key) {
        case GLUT_KEY_UP:
            viewer[1] -= 0.3;
            break;
        case GLUT_KEY_DOWN:
            viewer[1] += 0.3;
            break;
        case GLUT_KEY_LEFT:
            viewer[0] += 0.3;
            break;
        case GLUT_KEY_RIGHT:
            viewer[0] -= 0.3;
            break;
        case GLUT_KEY_F1:
            glPolygonMode(GL_FRONT_AND_BACK, GL_FILL);
            break;
        case GLUT_KEY_F2:
            glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);
            break;
    }
    myDisplay();
}

//处理菜单条目事件
void processMenuEvents(int option) {
    switch (option) {
        case POLYHEDRAL:
            glPolygonMode(GL_FRONT_AND_BACK, GL_FILL);//设置为多面体绘制
            break;

        case WIREFRAME:
            glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);//设置为线框体绘制
            break;
    }   
}

//创建菜单，供选择两种绘制模式
void createGLUTMenus() {
    glutCreateMenu(processMenuEvents);
    glutAddMenuEntry("Polyhedral", POLYHEDRAL);
    glutAddMenuEntry("Wireframe", WIREFRAME);
    glutAttachMenu(GLUT_MIDDLE_BUTTON);//与鼠标中间的按钮连接
}

int main(int argc, char **argv) {
    glutInit(&argc, argv);
    glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH);
    glutInitWindowSize(650, 650);
    glutCreateWindow("Dodecahedron");
    
    glutReshapeFunc(myReshape);
    glutDisplayFunc(myDisplay);
    glutIdleFunc(myIdle);

    glutMouseFunc(mouseButton);
    glutMotionFunc(mouseMotion);

    glutKeyboardFunc(processKeys);
    glutSpecialFunc(processSpecialKeys);

    glEnable(GL_DEPTH_TEST);

    createGLUTMenus();

    glutMainLoop();
    return 0;
}