The arguments of Filter should not be uv coord.

[finscn]

Example :
the center of ShockwaveFilter used uv coord, the x/y is [0.0 , 1.0].

When user want to use it , have to do some transform.

I know the transform is easy , but uv is the low layer in renderer, it should be black-box for the game coder.

And in real case , e.g. : a stone drop into a water .
The logic of game should be :

// water is a Sprite object.

var filter = new Shockwave(store.position);
water.filters = [filter];

It's easy and clear.

if Shockwave.center use uv coord.

the code maybe like this :

// water is a Sprite object.

var center = new PIXI.Point(0,0);
center.x = store.position.x / app.renderer.width;
center.y = store.position.y / app.renderer.height;
var filter = new Shockwave();

In fact , use app.renderer.width & app.renderer.height is wrong.
it's need use filterArea. but user can't get the filterArea easily.

So I think the filter should use screen/viewport/pixel coord, and filter do transform internal .