Event listener for sprite in camera

[afcruzs]

Is there any way to add a listener that triggers when a sprite is visible by the camera?. The object Sprite contains inCamera, but it seems to re compute the bounds of the sprite according to this: http://www.html5gamedevs.com/topic/8936-does-phaser-handle-object-visibility-according-to-camera/, and that can be expensive. In my case I need to do this for many sprites on the screen, so I want to know if there is a more efficient way to do it.

[samme]

If `sprite.checkWorldBounds` is on then you can use `sprite.inCamera` without any additional cost.

Otherwise you can check 

game.world.camera.view.intersectsRaw(sprite.left, sprite.right, sprite.top, sprite.bottom)

 

[afcruzs]

Thanks for your answer samme

In the docs (https://phaser.io/docs/2.6.2/Phaser.Sprite.html#checkWorldBounds) says that checkWorldBounds calculates the bounds every time and that it can be a expensive operation. Is it worst to use inCamera withouth having set checkWorldBounds to true?. Using intersectsRaw has linear time cost with respect to the size of camera.view.

I am not sure, but it seems like the 3 approaches end up doing calculations in linear time (maybe checkWorldBounds is faster?). I think that using a quadtree or a structure like that can make this operation much faster, but I don't know if the current API has something like that, of if that is even possible anyway.

[samme]

Either `checkWorldBounds` or `inCamera` triggers sprite.getBounds() so the cost of using one is probably similar to using both. But there's no reason to add `checkWorldBounds` if you don't need it.

Try `intersectsRaw()` and see if it performs OK. Otherwise you can try `arcade.overlap()`, which takes advantage of sorted Groups.

[afcruzs]

Thanks samme. I'll try that.