Small c++ game using graphics.h , calling multiple functions at once ? (multi threading?)

Question

I'm writing a small ball game. I have a function called gravity and I also have a while loop that checks whether the user wants to move the ball using wsad keys.

Do I need to multi thread this or is there another way out? I cut out some of the irrelevant code for setting up the program. Here is just the stuff that matters:

while(1) {
enableGravity();
char ch = getch();// i know getch() is not going to cut it
//maybe 2 different f() multi threaded , for gravity and position, 
f(ch == 'w' || ch == 'W')
                updateObjPosition('U');       
          else if(ch == 's' || ch == 'S')
                updateObjPosition('D');
          else if(ch == 'a' || ch == 'A')
                updateObjPosition('L');
          else  if(ch == 'd' || ch == 'D')
                updateObjPosition('R');

          }

I have these functions in main. I need the program to enable gravity and also be able to accept input to move the ball through updateObjPosition() simultaneously .

Answer 1

You could use multiple threads. A more obvious possibility would be a non-blocking keyboard read.

If you're doing this on Windows, you probably have a _kbhit in your standard library that will tell you if a key on the keyboard has been pressed. If you're using curses, you can use nodelay to tell getch to return immediately, whether a key has been pressed or not. Other systems may do things in different ways still, but you get the general idea...

Answer 2

You don't need to multi-thread. You just need an API that returns TRUE if a specified key is currently pressed down. That will likely be platform dependent. What platform are you building/running on?

For example on Win32: GetAsyncKeyState

Answer 3

As you have mentioned you are using old Borland compiler on TC 3.1 in the old conio.h there was a function

   kbhit(); 

the function was a one shot solution for getting if any key is pressed on the keyboard so here is your loop to get key input

  int getKey(){
     if(kbhit){
        return getch();
     }
     return -1;
 }

By they way you should upgrade to VC 08 Atleast!

For your simple project where the logic loop i guess will be quite small this will handle all the pain for you but if you write a longer application with hard logic then you will have to use better and Asynchronous methods for IO and those methods basically involve working on 2 threads 1 getting Input and the other doing logic operations ..