Question

I’ve created a structure called panel which render in OpenGL,works fine,but I want to add this to panel:

int flags;

then I define this in header :

#define PANEL_TITLE    0x0001
#define PANEL_MOVEABLE 0x0002
#define PANEL_SHADOW   0x0003

to use the flags value like this:

panel.flags = PANEL_TITLE | PANEL_MOVEABLE;

instead of have a lot :(which looks not good)

bool panel_has_title;
bool panel_moveable;
bool panel_shadow;

then check bool value,instead I can just have single int to achieve same result.I have read a lot open source stuff,that use flags,like the code above.
however my problem is it doesn’t work,when I check the flags with:

panel.flags = PANEL_TITLE | PANEL_MOVEABLE;
if(panel.flags & PANEL_TITLE) //this one works
{

}
if(panel.flags & PANEL_MOVEABLE) //this one doesn't work
{
  //not gets called
}

---

edit:
ok,now I’ve change it to

#define PANEL_TITLE    0x0002
#define PANEL_MOVEABLE 0x0004
#define PANEL_SHADOW   0x0008

are they intersect with each other again?
the new problem is if I set

panel.flags = PANEL_TITLE;

then every functions inside of it gets called

if(panel.flags & PANEL_TITLE)  
{
  //called which is normal
}
if(panel.flags & PANEL_MOVEABLE)  
{
  //called ..
}
if(panel.flags & PANEL_SHADOW)  
{
  //called ..
}

is it normal?

Answer 1

The problem here is that the bitmasks intersect with each other.
e.g. (simplefied for 8 bit)

#define PANEL_TITLE    0x0001 // 0b00000001
#define PANEL_MOVEABLE 0x0002 // 0b00000010
#define PANEL_SHADOW   0x0003 // 0b00000011

What you want is this:

#define PANEL_TITLE    0x0001 // 0b00000001
#define PANEL_MOVEABLE 0x0002 // 0b00000010
#define PANEL_SHADOW   0x0004 // 0b00000100

edit to your edit:

you don’t set them like that, you set them with:

panel.flags |= PANEL_TITLE;

And for the last problem, I can’t see anything wrong at first sight, try to step over it with a debugger and output the variable, that will give you a much clearer view of the problem