OpengGL - 旋转彩色立方体（glDrawElements & 鼠标键盘操作 & 三维图形变换）

程序运行效果：

---

代码如下：

#include<gl/glut.h>
#include<math.h>
#include<windows.h>
#include<algorithm>
using namespace std;
const GLubyte index[] = { 0, 3, 2, 1, 2, 3, 7, 6, 0, 4, 7, 3, 0, 1, 5, 4, 1, 2, 6, 5, 4, 5, 6, 7 };
const float vertex[] = { -1.0, -1.0, -1.0, 1.0, -1.0, -1.0, 1.0, 1.0, -1.0, -1.0, 1.0, -1.0,-1.0, -1.0, 1.0, 1.0, -1.0, 1.0, 1.0, 1.0, 1.0, -1.0, 1.0, 1.0 };
const float color[] = { 0, 0, 0, 1.0, 0, 0, 1.0, 1.0, 0, 0, 1.0, 0,0, 0, 1.0, 1.0, 0, 1.0, 1.0, 1.0, 1.0, 0, 1.0, 1.0 };
float speed = 0.1;
int der = 3;        //0x轴，1y轴，2z轴
float angle[] = { 0, 0, 0, 0 };
int pr_x, pr_y;     //上次鼠标位置
void myDisplay()
{
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);    //清除颜色缓存和深度缓存
    glLoadIdentity();

    glTranslated(0, 0, -6);
    glRotatef(angle[0], 1, 0, 0);
    glRotatef(angle[1], 0, 1, 0);
    glRotatef(angle[2], 0, 0, 1);

    glDrawElements(GL_QUADS, 24, GL_UNSIGNED_BYTE, index);      //绘制正方体

    glutSwapBuffers();
}
void idle()
{
    if (der == 3)
        return;
    angle[der] += speed;
    if (angle[der] > 360)
        angle[der] -= 360;
    if (angle[der] < 0)
        angle[der] += 360;
    glutPostRedisplay();
}
void keyboard(unsigned char key, int x, int y)
{   
    if (key == 27)      //按ESC退出程序
        exit(0);
    else if (key == '+')
        speed = min(1.0, speed + 0.02);
    else if (key == '-')
        speed = max(0.01, speed - 0.02);
    else if (key == 'x')
        der = 0;
    else if (key == 'y')
        der = 1;
    else if (key == 'z')
        der = 2;
    else if (key == 'p')
        der = 3;
}
void motion(int x,int y)
{
    if (der != 3)
        return;
    if (x > pr_x)
        angle[1] += 1.5;
    if (x < pr_x)
        angle[1] -= 1.5;
    if (y > pr_y)
        angle[0] += 1.5;
    if (y < pr_y)
        angle[0] -= 1.5;
    pr_x = x;
    pr_y = y;
    glutPostRedisplay();
}
void Reshape(int w, int h)      //两个参数：窗口被移动后大小
{
    glViewport(0, 0, w, h);
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    gluPerspective(45.0f, (GLfloat)w / (GLfloat)h, 0.1f, 100.0f);
    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity();
}

void initWindow(int &argc, char *argv[], int width, int height, char *title)    //初始化并显示到屏幕中央
{
    glutInit(&argc, argv);
    glutInitDisplayMode(GLUT_DOUBLE|GLUT_RGB|GLUT_DEPTH);       //使用双缓存模式和深度缓存
    glutInitWindowPosition((GetSystemMetrics(SM_CXSCREEN) - width) >> 1, (GetSystemMetrics(SM_CYSCREEN) - height) >> 1);       //指定窗口位置
    glutInitWindowSize(width, height);       //指定窗口大小
    glutCreateWindow(title);

    glClearColor(1, 1, 1, 0);
    glShadeModel(GL_SMOOTH);
    glEnable(GL_DEPTH_TEST);//激活深度测试

    glEnableClientState(GL_COLOR_ARRAY);
    glEnableClientState(GL_VERTEX_ARRAY);
    glVertexPointer(3, GL_FLOAT, 0, vertex);
    glColorPointer(3, GL_FLOAT, 0, color);

    pr_x = width / 2.0;
    pr_y = height / 2.0;
}

int main(int argc, char *argv[])
{
    initWindow(argc, argv, 600, 600, "彩色立方体");

    puts("\n键盘操作: \n\t+加速，-减速，p暂停旋转\n\tx围x轴旋转，y围y轴旋转，z围z轴旋转");
    puts("\n鼠标操作: 左键拖动实现旋转");

    glutDisplayFunc(myDisplay);
    glutReshapeFunc(Reshape);
    glutIdleFunc(idle);
    glutMotionFunc(motion);
    glutKeyboardFunc(keyboard);

    glutMainLoop();

    return 0;
}