给一个opengl动画C++的具体的例子

以下是一个简单的OpenGL动画C代码，它通过旋转一个立方体来展示OpenGL的基本功能：

#include <GL/glut.h>

float angle = 0.0f;

void display() {
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    glLoadIdentity();
    glTranslatef(0.0f, 0.0f, -5.0f);
    glRotatef(angle, 1.0f, 1.0f, 1.0f);
    glBegin(GL_QUADS);
    glColor3f(1.0f, 0.0f, 0.0f);
    glVertex3f(-1.0f, 1.0f, -1.0f);
    glVertex3f(-1.0f, -1.0f, -1.0f);
    glVertex3f(1.0f, -1.0f, -1.0f);
    glVertex3f(1.0f, 1.0f, -1.0f);
    glColor3f(0.0f, 1.0f, 0.0f);
    glVertex3f(-1.0f, 1.0f, 1.0f);
    glVertex3f(-1.0f, -1.0f, 1.0f);
    glVertex3f(1.0f, -1.0f, 1.0f);
    glVertex3f(1.0f, 1.0f, 1.0f);
    glColor3f(0.0f, 0.0f, 1.0f);
    glVertex3f(-1.0f, 1.0f, -1.0f);
    glVertex3f(-1.0f, -1.0f, -1.0f);
    glVertex3f(-1.0f, -1.0f, 1.0f);
    glVertex3f(-1.0f, 1.0f, 1.0f);
    glColor3f(1.0f, 1.0f, 0.0f);
    glVertex3f(1.0f, 1.0f, -1.0f);
    glVertex3f(1.0f, -1.0f, -1.0f);
    glVertex3f(1.0f, -1.0f, 1.0f);
    glVertex3f(1.0f, 1.0f, 1.0f);
    glColor3f(0.0f, 1.0f, 1.0f);
    glVertex3f(-1.0f, 1.0f, -1.0f);
    glVertex3f(1.0f, 1.0f, -1.0f);
    glVertex3f(1.0f, 1.0f, 1.0f);
    glVertex3f(-1.0f, 1.0f, 1.0f);
    glColor3f(1.0f, 0.0f, 1.0f);
    glVertex3f(-1.0f, -1.0f, -1.0f);
    glVertex3f(1.0f, -1.0f, -1.0f);
    glVertex3f(1.0f, -1.0f, 1.0f);
    glVertex3f(-1.0f, -1.0f, 1.0f);
    glEnd();
    glutSwapBuffers();
}

void reshape(int w, int h) {
    glViewport(0, 0, w, h);
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    gluPerspective(45.0f, (float)w / (float)h, 0.1f, 100.0f);
    glMatrixMode(GL_MODELVIEW);
}

void timer(int value) {
    angle += 2.0f;
    if (angle > 360.0f) angle -= 360.0f;
    glutPostRedisplay();
    glutTimerFunc(16, timer, 0);
}

int main(int argc, char **argv) {
    glutInit(&argc, argv);
    glutInitDisplayMode(GLUT_DOUBLE | GLUT_DEPTH);
    glutInitWindowSize(640, 480);
    glutCreateWindow("OpenGL Animation");
    glutDisplayFunc(display);
    glutReshapeFunc(reshape);
    glutTimerFunc(0, timer, 0);
    glEnable(GL_DEPTH_TEST);
    glutMainLoop();
    return 0;
}

该代码使用GLUT库创建一个新窗口，并在窗口中绘制一个旋转的立方体。在 `display()` 函数中，我们首先清除颜色缓冲区和深度缓冲区，并设置模型视图矩阵，然后使用 `glRotatef()` 函数旋转立方体。我们使用 `glBegin()` 和 `glEnd()` 函数之间的代码定义立方体的六个面，每个面使用不同的颜色。在 `reshape()` 函数中，我们设置视口和投影矩阵。在 `timer()` 函数中，我们增加角度值并在窗口中重新绘制旋转的立方体。

这是一个基本的OpenGL动画示例，它演示了如何使用OpenGL库创建一个简单的动画。