Cannot move objects at variable speeds.

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Interplanetary Funk

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Posted: 1st May 2010 20:17

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I've run into another snag while teaching myself DarkBasic, this time I'm trying to make an object accelerate when the up key is pressed. however, when I do press it nothing happens, it just stays still. Here's my code for the acceleration:

+ Code Snippet

FUNCTION Accelerate()
	if upkey()
		inc speed, (acceleration/(speed+1))
	else
		dec speed, (acceleration/(speed+1))
	endif
	move object 2, speed
ENDFUNCTION

the acceleration variable is set to a value of 70 (and is not changed anywhere in the program after being initialized) and speed is initialized at a value of 0.

the thing is, when I tell the object to move at a fixed value, e.g. "move object 2, 30" it will move fine, it's only when I try to use a variable it won't.

Massively confused as to why this is happening, I've just upgraded to v1.075 if that might be causing this otherwise I'm drawing blanks. any help would be great =)

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Indicium

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Posted: 1st May 2010 20:21

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You need to use floats for starts, and as those variables are in a function, you need to make them global.

Rawwrr. Sig Fail.
Newcastle is awesome

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Interplanetary Funk

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Posted: 1st May 2010 22:18

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The variables are global, and changing them to floats doesn't do anything =(

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Indicium

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Posted: 1st May 2010 23:39

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Can I see the rest of your code?

Rawwrr. Sig Fail.
Newcastle is awesome

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Interplanetary Funk

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Posted: 1st May 2010 23:50

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+ Code Snippet

sync on : sync rate 60
autocam off : color backdrop rgb(255, 255, 255)

load object "Track.dbo", 1 : set object collision to polygons 1

make object sphere 2, 10 : position object 2, 0, 100, -50 : hide object 2

acceleration as float = 70.0
speed as float = 0.0

make camera 1 : set current camera 1 : position camera 1, 0, 20, 0

DO
	position camera 1, object position x(2), object position y(2), object position z(2)
	
	accelerate()
	gravity()
	
	sync
LOOP

FUNCTION Accelerate()
	if upkey()
		inc speed, (acceleration/(speed+1.0))
	else
		dec speed, (acceleration/(speed+1.0))
	endif
	move object 2, speed
ENDFUNCTION

FUNCTION Gravity()
	origXrot= object angle x(2)
	origYrot= object angle y(2)
	origZrot= object angle z(2)
	
	rotate object 2, 90, 0, 0
	
	move object 2, 2
	if object collision(2, 0) then move object 2, -2
	
	rotate object 2, origXrot, origYrot, origZrot
ENDFUNCTION

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HowDo

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Posted: 1st May 2010 23:54 Edited at: 2nd May 2010 00:00

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if there isn't any other code then with the above bit if you do nothing then the object should start moving backwards, however if it was doing that you would not be posting about how to make it move.

qiuck look try knocking out this line and see what it does.

+ Code Snippet

FUNCTION Gravity()
	origXrot= object angle x(2)
	origYrot= object angle y(2)
	origZrot= object angle z(2)
	
	rotate object 2, 90, 0, 0
	
	rem  move object 2, 2
	if object collision(2, 0) then move object 2, -2
	
	rotate object 2, origXrot, origYrot, origZrot
ENDFUNCTION

Dark Physics makes any hot drink go cold.

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Interplanetary Funk

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Posted: 2nd May 2010 00:28

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Nope, makes no changes to anything, just doesn't make the object fall. =( (and that's my entire code for it atm)

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Sixty Squares

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Posted: 2nd May 2010 01:32

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Quote: "The variables are global, and changing them to floats doesn't do anything =( "

No they aren't

To make them global you have to write "global" when you declare them. So this:

+ Code Snippet

acceleration as float = 70.0
speed as float = 0.0

Should be this:

+ Code Snippet

GLOBAL acceleration as float = 70.0
GLOBAL speed as float = 0.0

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Garion

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Posted: 2nd May 2010 01:38 Edited at: 2nd May 2010 01:40

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for functions you need to define the variables as global... like this, Mad Nightmare has mentioned it but I can't see it in your code.

+ Code Snippet

global acceleration as float = 70.0
global speed as float = 0.0

By the way you can just use camera 0, the default one

And remember to position it above/next to the object and point camera at it or you won't see anything.

Edit:
Oops, too slow

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Interplanetary Funk

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Posted: 2nd May 2010 01:46

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Oh, I didn't know there was a global keyword, I presumed global variables worked as they do in c++ (the only language I actually know a bit about) anyway, it now works, so thank you very much =)

also, I know I can use the default camera, I just find it makes my code clearer to understand if I declare a camera 1 =)

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Garion

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Posted: 2nd May 2010 01:53

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Cool, keep coding

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TDK

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Posted: 2nd May 2010 17:06 Edited at: 2nd May 2010 17:08

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You wouldn't have that problem if you used a subroutine instead of a function (a void function in C++ terms I suppose).

Functions have a purpose - and IMHO the code you have in accelerate() and gravity() doesn't really warrant being in a function.

TDK

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DarkBASIC Professional Discussion / Cannot move objects at variable speeds.