GLUT's display func called only once

Suppose you have the following code in your main:

void Update(void){_tsp.update();}

void Display(void){_tsp.DrawCities();}

// your other code here

int main(int argc, char * argv[])

{

...

..

// your other code here

...

glutDisplayFunc(Display);  // callback for draw function

glutIdleFunc(Update);  //callbak for update function

You observe that the Display called only once and Update on all loops.

If you want both Display and Update be called, add

glutPostRedisplay(); 

In yor Update function at the end. This will trigger callback for the display-function.