sprites off screen

plamen · October 2012

Hey guys. I need some info about sprite off-screen rendering. Is it possible to keep sprite added to stage and not rendered when isVisible(false). Removing/adding to stage alters render order and for complex scenarios as RTS game is real pain. I think the parenting concept should be independent from render stack ordering. Or i am wrong? For example gun flames, missile tails, flamethrowers should be always on top and because there is no separate render layers as in MOAI it will be better to have visual optimization separated from game construction logic. Any help on the subject?

atilim · October 2012

You maintain the drawing order by putting different Sprites for different layers. For example, if you want draw gun flames, missile tails, flamethrowers always on top, add them to a Sprite as a child and put that Sprite on top of your stage.

plamen · October 2012

well here is the example. i have ship hull added to stage and moving on screen. I have rotating turret at a location added as a child of the hull so it will move with the ship and i have flame movie clip as child of the turret attached at the end of the turret. i need easy to switch on/off rendering of the group and still flame should be grouped with other flames of other turrets of other ships on top of everything.

atilim · October 2012

I understand now. and yes, it's a tricky situation. You need to put flames to a top Sprite and you can use Sprite:localToGlobal/Sprite:globalToLocal to display turret and flames always at the same position. (Still this is not a good and clean way).

plamen · October 2012

yeah :-) and to be more messy you can imagine how Sprite:localToGlobal/Sprite:globalToLocal works in system with additional parallax modifications. This is why i think render grouping/ordering should be somehow separated from object parenting. Still looking for elegant solution how to hide/unhide my ships when off-screen.

atilim · October 2012

Yes I totally agree

I'll think about adding a z-order parameter.

plamen · October 2012

isn't it easier to exclude sprites that are not visible from render stack still keeping their z-order. i mean easier to implement?

atilim · October 2012

I don't understand exactly. Do you mean by setting setVisible(false)? (There is already a function Sprite:setVisible to set the visibility of a sprite)

plamen · October 2012

well i understood that setVisible(false) doesn't exclude object from render stack, so it is not actual optimization method. right?

atilim · October 2012

If you set a sprite setVisible(false), that sprite and all of its children are excluded from rendering.

plamen · October 2012

really, then i misunderstood an older post that this is not happening at the moment?

atilim · October 2012

oh yes. But I still couldn't understand how setVisible can help to separate ordering from object parenting. :-/

plamen · October 2012

it won't but it will solve the off-screen rendering optimization with just hiding objects and not removing them from stage so z-order will be intact.

atilim · October 2012

aha! yes, exactly

(you can use setVisible(false/true) instead of removeChild/addChild)

plamen · October 2012

awesome! thanks for clearing this. i have trouble with sprite performance and i am into optimization stage now :-) This just kills me-

Its native code but still..

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