[OpenGL]课后案例10：立方体旋转程序

//A.10  利用顶点数组旋转立方体程序
/* rotating cube with vertex arrays */
#include <stdlib.h>
#include <GL/glut.h>
GLfloat vertices[] = {-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};
GLfloat colors[] = {0.0,0.0,0.0,1.0,0.0,0.0,
    1.0,1.0,0.0, 0.0,1.0,0.0, 0.0,0.0,1.0,
    1.0,0.0,1.0, 1.0,1.0,1.0, 0.0,1.0,1.0};
GLubyte cubeIndices[]={0,3,2,1,2,3,7,6,0,4,7,3,1,2,6,5,4,5,6,7,0,1,5,4};
static GLfloat theta[] = {0.0,0.0,0.0};
static GLint axis = 2;
void display(void)
{
    /* display callback, clear frame buffer and z buffer,
    rotate cube and draw, swap buffers */
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    glLoadIdentity();
    gluLookAt(1.0,1.0,1.0,0.0,0.0,0.0,0.0,1.0,0.0);
    glTranslatef(0.0, 3.0, 0.0);
    glRotatef(theta[0], 1.0, 0.0, 0.0);
    glRotatef(theta[1], 0.0, 1.0, 0.0);
    glRotatef(theta[2], 0.0, 0.0, 1.0);
    glColorPointer(3,GL_FLOAT, 0, colors);
    glDrawElements(GL_QUADS, 24, GL_UNSIGNED_BYTE, cubeIndices);
    glutSwapBuffers();
}
void spinCube()
{
    /* Idle callback, spin cube 2 degrees about selected axis */
    theta[axis] += 2.0;
    if( theta[axis] > 360.0 ) theta[axis] -= 360.0;
    glutPostRedisplay();
}
void mouse(int btn, int state, int x, int y)
{
    /* mouse callback, selects an axis about which to rotate */
    if(btn==GLUT_LEFT_BUTTON && state == GLUT_DOWN) axis = 0;
    if(btn==GLUT_MIDDLE_BUTTON && state == GLUT_DOWN) axis = 1;
    if(btn==GLUT_RIGHT_BUTTON && state == GLUT_DOWN) axis = 2;
}
void myReshape(int w, int h)
{
    glViewport(0, 0, w, h);
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    if (w <= h)
        glOrtho(-4.0, 4.0, -3.0 * (GLfloat) h / (GLfloat) w,
        5.0 * (GLfloat) h / (GLfloat) w, -10.0, 10.0);
    else
        glOrtho(-4.0 * (GLfloat) w / (GLfloat) h,
        4.0 * (GLfloat) w / (GLfloat) h, -3.0, 5.0, -10.0, 10.0);
    glMatrixMode(GL_MODELVIEW);
}
void main(int argc, char **argv)
{
    /* need both double buffering and z buffer */
    glutInit(&argc, argv);
    glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH);
    glutInitWindowSize(500, 500);
    glutCreateWindow("colorcube");
    glutReshapeFunc(myReshape);
    glutDisplayFunc(display);
    glutIdleFunc(spinCube);
    glutMouseFunc(mouse);
    glEnable(GL_DEPTH_TEST); /* Enable hidden--surface--removal */
    glEnableClientState(GL_COLOR_ARRAY);
    glEnableClientState(GL_VERTEX_ARRAY);
    glVertexPointer(3, GL_FLOAT, 0, vertices);
    glColorPointer(3,GL_FLOAT, 0, colors);
    glClearColor(1.0,1.0,1.0,1.0);
    glColor3f(1.0,1.0,1.0);
    glutMainLoop();
}