Animation frames out of order on Flash but not Windows

[IBwWG]

• Flixel version: dev (also flixel-demos)
• OpenFL version: 3.6.1
• Lime version: 2.9.1
• Affected targets:
  flash only

  ---

Open the TexturePackerAtlas demo, and unzip libgdx.zip into assets/libgdx/.

Then replace MenuState.hx with this:

package;

import flixel.FlxG;
import flixel.FlxObject;
import flixel.FlxSprite;
import flixel.FlxState;
import flixel.graphics.frames.FlxAtlasFrames;
import flixel.graphics.frames.FlxFrame;
import flixel.util.FlxColor;

class MenuState extends FlxState
{
    override public function create():Void
    {
        var tex9 = FlxAtlasFrames.fromLibGdx("assets/libgdx/libgdx-packed.png", "assets/libgdx/libgdx-packed.atlas");
        FlxG.debugger.drawDebug = true;
        FlxG.debugger.visible = true;
        bgColor = FlxColor.WHITE;
        var x11 = new FlxSprite(50, 50);
        x11.frames = tex9;
        x11.animation.addByPrefix("spin", "", 3);
        x11.animation.play("spin");
        add(x11);
        FlxG.watch.add(x11.animation, "frameIndex");


        // Remove atlas bitmaps from memory (useful for targets with hardware acceleration: cpp only atm).
        FlxG.bitmap.dumpCache();
    }
}

---

Observed behavior:

On Windows, the sequence is normal.
On Flash, I see the frames (with visuals to match) go by in this order: 3-1-2-0-4-5.

Expected behavior:

I'd expect Flash to also go 0-1-2-3-4-5.

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[Beeblerox]

if you set prefix parameter in animation.addByPrefix() method to "spin/" then it will work the same across the targets.
the "problem" is in FlxFrame.sortByName() static method which is used for sorting frames for animation.
But i'm not sure that this is actually a problem in this case, because when you specify prefix value as an empty string then this method tries to sort full strings "spin/1", "spin/2", etc.
But when you specify prefix as "spin/" then it sorts strings like "1", "2", etc.
And i believe that "Std.parseInt()" works differently (gives different results) across cpp and flash targets:
on cpp target it converts "spin/1" to 1 and on flash target it converts "spin/1" (and other strings like "spin/100500") to 0. that is why you have different results.

Of course we could make FlxFrame.sortByName() more complex to handle such cases, but while making those parsing and sorting methods i haven't expected that someone will "omit" prefix value when it necessary. i thought that method documentation makes it clear that you need to specify "common beginning of image names in atlas".

So what should we do:
a) handle this and similar cases in FlxFrame.sortByName() (this will require additional logic for converting frame names into numbers)
b) close this issue as showing incorrect usage of method?

[Beeblerox]

we can achieve desired result with regexp. This is what i got now

public static function sortByName(frame1:FlxFrame, frame2:FlxFrame, prefixLength:Int, postfixLength:Int):Int
    {
        var subName1 = frame1.name.substring(prefixLength, frame1.name.length - postfixLength);
        var subName2 = frame2.name.substring(prefixLength, frame2.name.length - postfixLength);

        var num1:Int = 0;
        var num2:Int = 0;

        var regex = ~/([0-9])+$/; // ([0-9])*[^0-9]+$

        if (regex.matchSub(subName1, 0))
        {
            num1 = Std.parseInt(regex.matched(0));
        }

        if (regex.matchSub(subName2, 0))
        {
            num2 = Std.parseInt(regex.matched(0));
        }

        return num1 - num2;
    }

[Beeblerox]

i know that it could be improved, but unfortunately i'm a total newbie with regular expressions

[Beeblerox]

updated method in my snippet, so it returns correct result

[Gama11]

And i believe that "Std.parseInt()" works differently (gives different results) across cpp and flash targets:
on cpp target it converts "spin/1" to 1 and on flash target it converts "spin/1" (and other strings like "spin/100500") to 0. that is why you have different results.

That doesn't sound right... We should look into that.

[Beeblerox]

@Gama11 i'll make example project for this behavior across different targeys, but in context of this issue this code works as expected (as i would expect it to work), it's just user's misuse of method parameters in my opinion

[Gama11]

The behavior is now consistent across platforms. You should still make sure to supply correct a correct Prefix parameter to addByPrefix() though (should be "split/" instead of an empty string).