Calling filterFrames.applyToSprite multiple times on the same sprite makes the offset of that sprite to grow each time

[JasperHorn]

• Haxe version: 4.3.1
• Flixel version: 5.3.1
• OpenFL version: 9.2.2
• Lime version: 8.0.2
• Affected targets: Tested html, but probably any

---

Code snippet reproducing the issue:

package;

import flixel.FlxG;
import flixel.FlxSprite;
import flixel.FlxState;
import flixel.graphics.frames.FlxFilterFrames;
import flixel.tweens.FlxTween;
import flixel.util.FlxColor;
import openfl.filters.GlowFilter;

class PlayState extends FlxState
{
	static inline var SIZE_INCREASE:Int = 5;

	var spr:FlxSprite;
	var filterFrames:FlxFilterFrames;

	var running:Bool = false;
	var tween:FlxTween;

	override public function create():Void
	{
		FlxG.camera.bgColor = 0xFF01355F;

		var glowFilter = new GlowFilter(0xFF0000, 1, 50, 50, 1.5, 1);
		spr = new FlxSprite(200, 200);
		spr.makeGraphic(10, 10, FlxColor.BROWN);
		add(spr);
		filterFrames = FlxFilterFrames.fromFrames(spr.frames, SIZE_INCREASE, SIZE_INCREASE, [glowFilter]);

		// The tween isn't necessary for the bug, but without it, reapplying the
		// filter frames doesn't really make sense...
		tween = FlxTween.tween(glowFilter, {blurX: 4, blurY: 4}, 1, {type: PINGPONG});
		tween.active = true;
	}

	override public function update(elapsed:Float):Void
	{
		// The whole running thing isn't necessary for the bug
		// I added it because it makes the bug easier to see
		if (FlxG.mouse.justPressed)
		{
			running = true;
		}

		super.update(elapsed);

		if (running)
		{
			filterFrames.applyToSprite(spr, false, true);
		}
	}
}

(Note: this is just https://haxeflixel.com/demos/FlxSpriteFilters/ cut down to a minimal sample for this bug)

---

Observed behavior:

After you click, the screen, the sprite flies off the screen.

Expected behavior:

After you click the screen, the sprite stays where it is supposed to, and an animated blur filter starts being applied to it.

Cause of problem:

This bug was introduced with this change: #2176

Before that change, you could call FlxFilterFrames.applyToSprite() repeatedly on the same sprite, but calling it on a sprite that had a non-zero offset would lead to wrong result. After the change, non-zero offsets would work as expected, but calling it repeatedly no longer did.

I don't see a simple solution that keeps the behavior as expected in both situations. The best I can come up with is keeping a list of sprites that the frames have been applied to, but that doesn't eliminate the bug but just pushes it to a more complicated spot (namely, if you call it again after changing the graphics, but do have an offset). Perhaps the way to go is to create two methods - or an extra argument - and leave discerning the two situations to the user. But that's a more architectural choice.