character jumping

Hello, I'm having a bit of trouble with getting my character to jump, I've looked around the forums and haven't found a solution to my problem so yeah, here I am :P

So far I have this:

Code:

---

if(GetAsyncKeyState(VK_SPACE)) person1.jump = true;


if(person1.jump == true){
        person1.y += person1.jumpVel;
        person1.jumpVel = (person1.jumpVel - person1.gravity);
   
        if(groundCollision()){
            person1.jumpVel = person1.oldy;
            person1.jump = false;
        }
    }

---

The value of jumpVel is 2; and gravity is 0.2;
That's in my main game loop. The problem is when I hit space the character goes up and doesn't stop, and then the program freezes.

Any help would be most appreciated :).

I am not an expert in Windows programming, but the description of GetAsyncKeyState says the following about the return value:

Quote:

---

... If the most significant bit is set, the key is down ...
...
The return value is zero for the following cases:

The current desktop is not the active desktop
The foreground thread belongs to another process and the desktop does not allow the hook or the journal record.
...

---

Therefore GetAsyncKeyState(VK_SPACE) always returns true, you should instead check the most significant bit of the return value (it's a SHORT not a BOOL).

Jumping is done by applying a force in the +Y direction (if +Y is up in your system) and then letting the physics take care of it from there. Your physics should already be applying a down force on dynamic objects.