通过将函数作为参数而不是函数指针传递的openGL代码如何工作？

Question

The following openGL code APPARENTLY passes display function as an argument to glutDisplayFunction. In reality only a function pointer can be passed as argument to glutDisplayFunction. I wonder how this program is running successfully?

#include <GL/glut.h>
#include<GL/gl.h>// Header File For The GLUT Library

void init(void)
{
    glClearColor (0.0,0.0,0.4,0.0);
    glShadeModel(GL_FLAT);
}

void reshape (int w, int h)
{
    glViewport(0,0, (GLsizei) w, (GLsizei)h);   // indicates the shape of the available screen area into which the scene is mapped
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    glOrtho(-10,10,-10,10,-10,10);


}

void display (void)
{
    int i,j;

    while(1){
    for (i=-10; i <=10; i++){
    glClearColor (1.0,0.0,0.0,0.0);
    glClear(GL_COLOR_BUFFER_BIT);
    glColor3f(0.0, 0.0, 1.0);
    glBegin(GL_TRIANGLES);
        glVertex3f(i,2,5);
        glVertex3f(6,-i,-5);
        glVertex3f(1,9,-1);
    glEnd();
    glFlush();}
    }
}

int main (int argc, char *argv[])
{
    glutInit(&argc, argv);
    glutInitDisplayMode (GLUT_SINGLE | GLUT_RGB);
    glutInitWindowPosition(100,100);
    glutInitWindowSize(500,500);
    glutCreateWindow (argv[0]);
    init ();
    glutDisplayFunc(display);
    glutReshapeFunc(reshape);
    glutMainLoop ();
    return 0;
}

Answer 1

Passing the name of a function without parentheses as an argument implicitly passes a pointer to the function. It is not possible to pass a function by value in C.

Answer 2

We need not use & operator to create a reference to a function.We can pass 'display' to 'glutDisplayFunc' directly. Something Like array name referring to address of first element?

This -glutDisplayFunc(&display) - also should be fine