Hello World with OpenGL and GLUT

So I followed the spin shape function (somewhat modified) from the OpenGL Programming Guide, a.k.a. the Red Book, and followed Chapters 1 and 2.

What it does is spin a square slowly. The original Red Book version spun really fast. And since I'm using a MacBook Pro, which only has a trackpad, the spinning pauses on Right-Click instead of Middle-Click.

Then, I modified the program to spin a 5-vertex polygon instead:

While the rest more or less follows the guide, here's the code that adds a vertex, reduces spin speed and changes button used:

void display()

{

    glClear(GL_COLOR_BUFFER_BIT);

    glPushMatrix();

    glRotatef(spin, 0.0, 0.0, 1.0);

    glColor3f(0.1, .5, .6);

    glBegin(GL_POLYGON);

        glVertex2f(-25, 25);

        glVertex2f(-25, 25);

        glVertex2f(0, 30);

        glVertex2f(25, 25);

        glVertex2f(25, -25);

    glEnd();

    glPopMatrix();

    glutSwapBuffers();

}

void spinDisplay()

{

    spin = spin + .002;

    if (spin > 360)

        spin = spin -360;

    glutPostRedisplay();

}

void mouse(int button, int state, int x, int y)

{

    switch (button)

    {

        case GLUT_LEFT_BUTTON:

            if (state == GLUT_DOWN)

                glutIdleFunc(spinDisplay);

            break;

        case GLUT_RIGHT_BUTTON:

            if (state == GLUT_DOWN)

                glutIdleFunc(NULL);

            break;

        default:

            break;

    }  

}