Problem with Type in a Function
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| If I have 5 targets created as types ie target_1, target_2 etc and I want to find the x,y postion of any of those targets how can I write an if statement to check the target I want I wrote this but am unable to add a variable after 'target_'. If I want 'target_3' how can I add the '3' to the end of 'target_'? Also how do the variables I pass into the function get returned? Function check_target_pos(target_num,x,y) ; If target_ \x=0 End End Function Many thanks for reading Graham, UK |
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Have a look:
type example
field x
end type
o.example=new example
o\x=50
function something()
print o\x
end function
will not work because you've declared "o" as a local (by default) and you cannot access it in functions. But you can access types using a built in list for each type... erm.. type. If you want to individualise instances of types then it's a good idea to give them a unique ID you can use later to identify them. Regard:
type example
field x,y
field id ; unique ID (it's your responsibility to make them unique)
end type
; create two local example. These aren't accessable in functions.
o.example=new example
o\id=1
o\x=50
o2.example=new example
o2\id=2
o2\x=100
; run a program
Check_Target_Pos(1) ; try and check ID 1
waitkey
end
function Check_Target_Pos(number)
local found.example=null
found=getTypeByID(number) ; try and find 'number'
if found <> null ; check to see whether it's found it.
; do whatever you want with 'found'
; if found\x=0 then end
else
Print("Could not find example "+number)
endif
end function
function getTypeByID.example(idNumber)
; this function will cycle the list
; of examples currently created within your game
; if the example type we're cycling through
; has the same ID number as the parameter,
; it's the type we want. We return it. Note the return
; value of this function
for i.example=each example
if i\id = idNumber then return i
next
end function
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Or you can do like this:
Type Target
Field X,Y
End Type
Target_1.Target=New Target
Target_2.Target=New Target
Target_1\X=5
Check_Target_Pos(Target_1,5,5)
Function Check_Target_Pos(Target_Num.Target,X,Y)
If Target_Num\X=5 Then Print("Target\x=5"):WaitKey
End Function
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| Yeah, or you could do it like that. ;) |
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| ;create globals Global gfx_x=640 Global gfx_y=480 Global gfx_colour_depth=16 Global id ;========================================================================================== ;create window Graphics gfx_x,gfx_y,gfx_colour_depth,2 ;screen =640,480,16 bit colour, always windowed AppTitle="Shape Shoot" SetBuffer BackBuffer() ;========================================================================================== ;create types Type target Field x=0 ;x pos Field y=0 ; y pos Field id ; id number of target Field hit=False ;target hit/miss Field image ;target graphic End Type ;========================================================================================== ;create objects from types target_1.target=New target target_1\x=0 target_1\y=0 target_1\id=1 target_1\hit=False target_1\image=LoadImage("target.bmp") ;x40,y40 pixels MaskImage (target_1\image,255,255,255) ;get rid of the surrounding white of the image ;========================================================================================== ;main loop While Not KeyHit (1) Cls Gosub debug_output ;draw the target on the screen DrawImage target_1\image,target_1\x,target_1\y ;increase x and y co-ordinates of the target target_1\x=target_1\x+5 target_1\y=target_1\y+5 ;slight delay in the movement of target Delay(100) ;check the onscreen position of target check_target_pos(1) ;flip the buffer screen Flip Wend End ;========================================================================================== ;create functions Function check_target_pos(id) ;used to check the position of any targets on screen Local found.target=Null found=get_target_id(id) ; try and find 'number' If found <> Null ; check to see whether it's found it. Text(0,0,"found "+id) ;ok so i found that it is number 1 so how can i now say ;If target_1\x < 0 Then etc etc ;i cannot use target_id as it is not a declared type Else Text(0,0,"Could not find example "+id) EndIf End Function Function get_target_id.target(id) ;cycle through all availible targets and return the id For i.target=Each target If i\id = id Then Return i Next End Function ;========================================================================================== ;debug .debug_output Text(0,400,"target 1 x="+target_1\x+" y="+target_1\y) Return |
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| Please read the comments in Function check_target_pos(id) and try and help me pleeeeeaaase! |
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You use "found" instead. Basically, what it's doing is this:
Function check_target_pos(id)
; here, you're finding the instance of the target type
; that has the id you're looking for and putting it into
; found.
; It's the same as saying:
; j.target=new target
; a.target=null
; a = j
; You're basically pointing to it. It's not being copied,
; just being pointed to with a different name.
; This is what you're doing below. You're declaring "found"
; and then making it point to the target with
; the ID you're looking for.
Local found.target=Null
found=get_target_id(id)
If found <> Null ; check to see whether it's found it.
Text(0,0,"found "+found\id+", "+found\x+", "+found\y)
;If found\x < 0 Then etc etc
Else
Text(0,0,"Could not find example "+id)
EndIf
End Function
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| Check this out, ( Lol I'm to slow, some one was faster ) Function check_target_pos(id) ;used to check the position of any targets on screen Local found.target=Null found=get_target_id(id) ; try and find 'number' If found <> Null ; check to see whether it's found it. Text(0,0,"found "+id) ;ok so i found that it is number 1 so how can i now say ;If target_1\x < 0 Then etc etc ;Like This...... If found\x < 0 Then ;etc etc Else Text(0,0,"Could not find example "+id) EndIf End Function bye... |
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| Sorry tiger! |
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| thanks guys, its so much clearer now!! really appreciated |
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| If you want the X-value of a specific type-instance, there are two options: - you add a field (i.e. InstanceNumber%) to your type and when you want to get the X-value of a certain type, you can loop through all types of type "Target" (with First, Each, Before, After, ...) and check if the field matches the one you want the X-value from - use arrays of types (my favorite choice, instant access, no looping needed) Arrays are always global, so you have access to them at any time. Like this: Type Target Field X% Field Y% End Type dim ArrayOfTargets.Target(5) ; Creates an array with indexes 0-5 and prepares it to hold pointers to "Target"-type-instances. ; Create all instances and put the pointers into the array For i = 1 to 5 ArrayOfTypes(i) = New Target Next ; Now all (5) type-instances are created and each (index 1-5) index of the array points to such an instance. ; Your function: Function check_target_pos(target_num,x,y) ; If ArrayOfTargets(target_num)\x=0 End End Function |
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