freeglut (./a.out): ERROR: No display callback registered for window 1

Question

I'm trying to get started in learning how to make graphics with C.

#include <GL/glut.h>
int main(int argc, char **argv, char **envp) {                                                   
  glutInit(&argc, argv);     
  glutCreateWindow("test");
  glutMainLoop();
  return 0;
}

This was compiled with gcc test.c -l glut. Upon execution, the following error is printed: freeglut (./a.out): ERROR: No display callback registered for window 1. What can be the cause of this, and what could be done to fix it?

Answer 1

You have to sets the display callback for the current window with glutDisplayFunc before you enter the event processing loop with glutMainLoop:

#include <GL/glut.h>

void display(void);

int main(int argc, char **argv, char **envp) {                                                   
  glutInit(&argc, argv);     
  glutCreateWindow("test");
  glutDisplayFunc(display);
  glutMainLoop();
  return 0;
}

void display(void)
{
  /* ... */
}