Tweening - GameCreators Forum

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george++

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Joined: 13th May 2007

Location: Thessaloniki, Hellas

Posted: 29th Oct 2016 19:14

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Hi,
Please take a look at the following snippet

+ Code Snippet

SetWindowSize(800, 480, 0)
SetVirtualResolution(800, 480)

my_tween = CreateTweenCustom(2.0)
SetTweenCustomInteger1(my_tween, 1000, 0, 0)
begin = GetTweenCustomInteger1(my_tween)

do
	// press left mouse button or tap screen to start
	if GetPointerPressed() = 1
		PlayTweenCustom(my_tween,0.0)
	endif
	// get the tween value
	tween_value = GetTweenCustomInteger1(my_tween)
	Print("begin=" + str(begin))
	print(tween_value)
	UpdateAllTweens( getframetime() )
	sync()
loop

what is the proper behavior of the following command:

+ Code Snippet

GetTweenCustomInteger1(my_tween)

Why the 'begin' variable does not equal to 1000 after the following code:

+ Code Snippet

begin = GetTweenCustomInteger1(my_tween)

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BatVink

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Joined: 4th Apr 2003

Location: Gods own County, UK

Posted: 29th Oct 2016 22:54

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The initial value doesn't get set until you play the tween.

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Quidquid latine dictum sit, altum sonatur
TutCity is being rebuilt

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george++

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Location: Thessaloniki, Hellas

Posted: 30th Oct 2016 02:31

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Why not immediately?

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BatVink

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Posted: 30th Oct 2016 08:34 Edited at: 30th Oct 2016 08:34

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In the first step, you have described how you want the tween to behave. but it doesn't actually breathe life until you play it.

I would code it "back to front". I would set the begin variable to 1000, and then set the tween start value to begin.
This solves the immediate problem.
Also, when you look back at your code in 6 months time it will make sense without having to write a paragraph of comments in your code.

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Quidquid latine dictum sit, altum sonatur
TutCity is being rebuilt

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george++

AGK Tool Maker

17

Years of Service

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Joined: 13th May 2007

Location: Thessaloniki, Hellas

Posted: 30th Oct 2016 13:48 Edited at: 30th Oct 2016 14:02

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Your suggestion does not solve the following scenario:
I have a sprite and I want to tween its CURRENT color alpha to another value (lets say to 0.0)
Take a look at the following snippet:

+ Code Snippet

SetWindowSize(800, 480, 0)
SetVirtualResolution(800, 480)

my_sprite = CreateSprite(0)
SetSpriteSize(my_sprite, 64, 64)
SetSpritePosition(my_sprite, 400.0, 240.0)

SetSpriteColorAlpha(my_sprite, 128)
alpha_begin = GetSpriteColorAlpha(my_sprite)

my_tween = CreateTweenCustom(2.0)
SetTweenCustomInteger1(my_tween, alpha_begin, 0, 0)

do
	// press left mouse button or tap screen to start
	if GetPointerPressed() = 1
		PlayTweenCustom(my_tween, 3.0)
	endif
	// get the tween value
	tween_value = GetTweenCustomInteger1(my_tween)
	SetSpriteColorAlpha(my_sprite, tween_value)	
	Print("Click to start the tweening")
	Print("begin=" + str(alpha_begin))
	print(tween_value)
	UpdateAllTweens( getframetime() )
	sync()
loop

the sprite will not be visible until the tween starts. In our case it will be visible after 3.0 seconds

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BatVink

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Joined: 4th Apr 2003

Location: Gods own County, UK

Posted: 30th Oct 2016 14:07

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A couple of thoughts...

Remove line 13. alpha_begin already has the correct value, you are setting it to an incorrect value of 0 because the tween isn't playing yet.
Line 21/22 should be:

+ Code Snippet

if getTweenCustomPlaying(my_tween)
    tween_value = GetTweenCustomInteger1(my_tween)
    SetSpriteColorAlpha(my_sprite, tween_value) 
endif

And thirdly, you could simplify by using CreateTweenSprite and SetTweenSpriteAlpha.

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Quidquid latine dictum sit, altum sonatur
TutCity is being rebuilt

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george++

AGK Tool Maker

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Joined: 13th May 2007

Location: Thessaloniki, Hellas

Posted: 30th Oct 2016 15:08 Edited at: 30th Oct 2016 16:37

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Thanks for the tip. But your suggestion adds an 'if' statement in the loop.
Having the value set at the beginning then we have an 'if' less.
[EDIT]
Could you please post the whole snippet?

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BatVink

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Posted: 30th Oct 2016 20:33

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You need the if statement otherwise you will get the tween value when the tween is not playing, it will be zero and the sprite will turn invisible. The if statement ensures that you only process the fade when the poiner has been clicked.

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Quidquid latine dictum sit, altum sonatur
TutCity is being rebuilt

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