problem with stacking "KeyHits"

Blitz3D Forums/Blitz3D Beginners Area/problem with stacking "KeyHits"

DeadSquirrel

(Posted 2004) [#1]

I've just encounter an odd problem, never happened to me before.
It seems that "KeyHits" for the same key, no longer stack.

Say ou have two "If" loops, both need a KeyHit(28) [enter],
but both have differing conditions needed...

	If selectpos = 3 And KeyHit(28) ; For options
		Goto options
	EndIf
	
	If selectpos = 1 And KeyHit(28) ; For game start
		Goto gamestart
	EndIf

Only the first one will work when Enter is hit with the right conditions (goto otpions).
The second loop ignores your keyhit(28), even if selectpos = 1.

I tried inversing the order of the loops:

	If selectpos = 1 And KeyHit(28) ; For game start
		Goto gamestart
	EndIf

        If selectpos = 3 And KeyHit(28) ; For options
		Goto options
	EndIf

Now only the "Goto gamestart" loop works, when KeyHit(28) happens.
The second loops is yet again, ignored.

As if the KeyHit(28) worked only for the first loop, and was ignored for any following loops.

Is this a bug? or am I missing something?

Thanks for any insight :)

WolRon

(Posted 2004) [#2]

That's normal.

What you have to do is set the returned value from KeyHit(28) to a variable and then test the variable.

Like so:

KH28 = KeyHit(28)
If selectpos = 1 And KH28 ; For game start
  Goto gamestart
EndIf

If selectpos = 3 And KH28 ; For options
  Goto options
EndIf

or a little more optimized:

KH28 = KeyHit(28)
If KH28
  If selectpos = 1 ; For game start
    Goto gamestart
  EndIf

  If selectpos = 3 ; For options
    Goto options
  EndIf
EndIf

(A little note: The KeyHit command actually returns the NUMBER of keyhits since the last time it was checked. So, in my example above, KH28 could actually contain a value higher than 1 depending on how often you check it's returned value.)

DeadSquirrel

(Posted 2004) [#3]

Ah I see, thanks :). I'm surprised I never came across this same problem before though.
Never replaced keyhits with variables before.. guess it's a habit I need to get used to.

jhocking

(Posted 2004) [#4]

The problem is that KeyHit returns the number of times the key was hit since last time you called the command. If you call KeyHit multiple times a frame, it'll return the keypress the first time but none of the other times (ie. the key was hit 0 times since the last time you called KeyHit.) Thus it is vital to only call KeyHit once a frame.

Either do what WolRon suggested of storing the keyhits in variables, or nest your if statements. His second code snippet uses nested if statements; storing KeyHit in a variable is unnecessary in that case. It would look like:

If KeyHit(28)

If something
If something else

EndIf

Thus KeyHit is only called once.