PT Forum

BatVink Joined: 4th Apr 2003
Location: Gods own County, UK

Posted: 24th Sep 2011 16:55

Can anyone spot my mistake here? The idea is that as the viewport moves, the background appears stationary as it follows the viewport. However, the sprite seems to be frozen at 0,0 and won't move. I have the getSpriteX() on screen and it is definitely changing.

+ Code Snippet

    if getSpriteX(gShip) - getViewOffSetx() &gt; 220 and getViewOffSetX() &lt; 1056
        setViewOffset(getViewOffSetx() + 1, getViewOffsetY())
        gBackdropX = gBackdropX + 1
        setSpritePosition(gBackdropSprite, gBackdropX, getSpriteY(gBackdropSprite))
    endif

    if getSpriteX(gShip) - getViewOffSetx() &lt; 260 and getViewOffSetX() &gt; 0
        setViewOffset(getViewOffSetx() - 1, getViewOffsetY())
        gBackdropX = gBackdropX - 1
        setSpritePosition(gBackdropSprite, gBackdropX, getSpriteY(gBackdropSprite))
    endif

The value for the Sprite X value is displayed and moves as expected:

+ Code Snippet

setTextString(gTextDebug, "Sprite X   : " + str(getSpriteX(gBackdropSprite)))

The Slayer Joined: 9th Nov 2009
Location: (Hide and) Seek and Destroy on my guitar!

Posted: 24th Sep 2011 18:41

The idea is that as the viewport moves, the background appears stationary as it follows the viewport. However, the sprite seems to be frozen at 0,0 and won't move. I have the getSpriteX() on screen and it is definitely changing.

If the background remains stationary (because it follows the viewport), the values would not change, right?
And, you are adding 1 to the variable 'gBackdropX', which you are retrieving by GetSpriteX (gBackdropX)?

BatVink Joined: 4th Apr 2003
Location: Gods own County, UK

Posted: 24th Sep 2011 23:42

If the background remains stationary (because it follows the viewport), the values would not change, right?

If the Viewport is offset by 1, then the backdrop must be offset by 1 in order to be stationary in the eyes of the player. At least, that's the way I have interpreted the way the viewport works. I actually want it to scroll very slowly,but in order to prove the theory I'm using this 1:1 relationship.

DVader Joined: 28th Jan 2004
Location:

Posted: 25th Sep 2011 1:08

I haven't used the viewport command, but I would have thought if you are moving the viewport like a camera to move around, you would want to keep the back drop at the same place. If you offset it the same as the viewport the backdrop will stay still as you are offsetting it with the viewports movement. The sprite positions will change, but as everything is being offset anyway they will appear stationary.
I think that is the problem anyway.

BatVink Joined: 4th Apr 2003
Location: Gods own County, UK

Posted: 25th Sep 2011 23:31

DVader, that is exactly what I want to achieve - stationary background whilst the foreground moves with the viewport.

Rich Dersheimer Joined: 1st Jul 2009
Location: Inside the box

Posted: 26th Sep 2011 1:33

If you truly want your background stationary, can't you just lock it to the screen? Or am I missing the point?

And even after you lock it to the screen, you can still move it. At least I think that's the case. Hmmm... maybe just scrolling the U part of the sprite U/V?

empty Joined: 26th Aug 2002
Location: 3 boats down from the candy

Posted: 26th Sep 2011 3:16

Are you sure that gBackdropSprite holds the correct handle?
This quick test works for me:

+ Code Snippet

backdrop = CreateSprite(LoadImage("background.jpg"))
sprite = CreateSprite(LoadImage("test.jpg"))

Do
    Inc (counter)
    If counter Mod 10 = 0
        Inc (bgd)
        SetSpritePosition(backdrop, bgd, bgd)
        SetViewOffset(GetViewOffsetX()+1,GetViewOffsetY()+1)
    EndIf
    SetSpritePosition(sprite, 50, 50)
    Sync()
Loop

The backdrop sprite stays stationary while the foreground sprite slowly slides out of the moving viewport.

BatVink Joined: 4th Apr 2003
Location: Gods own County, UK

Posted: 28th Sep 2011 0:57

Fixed with the new update.

LeeBamber Joined: 21st Jan 2000
Location: England

Posted: 9th Oct 2011 3:22

Happy to help

Any more issues, remember we are always listening here: http://code.google.com/p/agk/issues/list

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