OpenGL - Left mouse click keeps removing my grid - c++

Question

I have created a drawGrid() function that draws a squared grid along my X and Y axis, which works fine. I have then created a menu() function (called in the main()), that toggles the grid on and off, here's the code for that:
void menu(int item)
{
switch (item)
{
case MENU_SWITCH_OFF_GRID:
{
if (gridActive == true)
{
gridActive = true;
}
}
break;
case MENU_SWITCH_ON_GRID:
{
if (gridActive == true)
{
gridActive = false;
}
}
break;
default:
{ /* Nothing */ }
break;
}
glutPostRedisplay();
return;
}
}
The menu switch works fine, as I have created a global variable called gridActive without a true or false value so it doesn't reset each time, that way it can be accessed in my display() function like so:
if (gridActive != true)
{
drawGrid();
gridActive = true;
}
All of this works just fine.
What's my issue?
My issue is, whenever I click the left mouse button, my grid disappears, which I don't want. So I've made a mouse() function like this:
case GLUT_LEFT_BUTTON: if (state == GLUT_DOWN)
{
exit(0); // this has been added to see if
// my program will exit!
}
break;
To test if my program exits when I click the left mouse, and it does.
So instead of using exit(0); what code can i put here so that my grid doesn't disappear when I click the left mouse button? Or is the issue beyond that?
UPDATE:
Here's the mouse function:
void mouse(int button, int state, int x, int y)
{
// these have simply been set-up for me to use
// in the future
switch (button)
{
case GLUT_LEFT_BUTTON: if (state == GLUT_DOWN)
{
}
break;
case GLUT_RIGHT_BUTTON: if (state == GLUT_DOWN)
{
}
break;
default: break;
}
}

Answer 1

Based on your code:
if (gridActive != true)
{
drawGrid();
gridActive = true;
}
You only draw the grid when gridActive is false. However, after every time you draw it, you set gridActive=true which will then stop it from being drawn.

Answer 2

Without more of your code, it's impossible to tell exactly what's going on, but these lines may not be doing what you think they are, and that may be causing some issues.
This never does anything.
if (gridActive == true)
{
gridActive = true;
}
This:
if (gridActive == true)
{
gridActive = false;
}
is the same as:
gridActive = false;
In order to tell what's going on, though, we need to know what happens when you click your mouse button when the exit call isn't there, but you didn't post that code yet.
Also, i don't quite know what you mean by:
I have created a global variable called gridActive without a true or false value so it doesn't reset each time
but it sounds like you made an uninitialized global variable and expect that it has some specific meaning because it's uninitialized?