Semi-transparent colors in sprites turn black on -Dnext

[starry-abyss]

• Flixel version: dev
• OpenFL version: 3.6.1
• Lime version: 2.9.1
• Affected targets: neko, windows

---

Code snippet reproducing the issue:

package;

import flixel.FlxSprite;
import flixel.FlxState;
import flixel.util.FlxColor;

class PlayState extends FlxState {
    var sprite:FlxSprite;
    
    override public function create():Void {
        super.create();
        sprite = new FlxSprite();
        sprite.makeGraphic(300, 300, FlxColor.RED & 0x88FFFFFF);
        add(sprite);
        bgColor = FlxColor.GREEN;
    }
}

If I remove the & 0x88ffffff part, the sprite is plain red (which is good) on both legacy and next.

---

Observed behavior:
(next)

Expected behavior:
(legacy and Flash)

[IBwWG]

I'm getting this also on linux64 with haxe 3.4.0, haxeflixel 4.2.0, openfl 3.6.1, lime 2.9.1.

lime test neko:

lime test neko -Dnext:

As you can see, the effect is dramatic as soon as you're 1/255th less than full alpha, and gets worse from there.

Code used:

package;

import flixel.FlxState;
import flixel.FlxSprite;
import flixel.util.FlxColor;

class PlayState extends FlxState
{
	override public function create():Void
	{
		super.create();
		for (i in 0...256) {
			var box = new FlxSprite();
			var colour = new FlxColor(FlxColor.WHITE);
			colour.alpha = 256 - i;
			box.makeGraphic(10, 120, colour);
			box.setPosition(10 * (i % 64), 120 * Std.int(i / 64));
			add(box);
		}
	}
}

[Tembac]

This is maybe a problem with openfl 3.6.1.

I had a similar problem before using only openfl. It was supposedly fixed october 2015: http://community.openfl.org/t/several-problems-with-swf-from-fla-and-windows-target/6628

[Gama11]

@Tembac OpenFL 3.6.1 should have that fix then, it was released 2016-03-29.

[Tembac]

Ups, I have my years mixed :D jaja.

[Gama11]

@Beeblerox I wanted to see whether this will be fixed by #2068 - it seems the color of the sprite in the upper left is somewhat off on the FlxMaterial branch:

vs Flash (expected):

[Beeblerox]

@Gama11 i will look into it.

[Beeblerox]

@Gama11 i think the problem on my branch is caused by shaders which suppose to work with premultiplied alpha. So in order to fix this i need to add new property to material and chose shader appropriately.

You can check it yourself if you change DEFAULT_FRAGMENT_SOURCE constant it flixel.graphics.shaders.quads.FlxTexturedShader class to:

	public static inline var DEFAULT_FRAGMENT_SOURCE:String = 
			"
			varying vec2 vTexCoord;
			varying vec4 vColor;
			varying vec4 vColorOffset;
			
			uniform sampler2D uImage0;
			
			void main(void) 
			{
				vec4 color = texture2D(uImage0, vTexCoord);
				
				vec4 result = color * vColor + vColorOffset;
				result = clamp(result, 0.0, 1.0);
				
				gl_FragColor = result;
			}";

[Gama11]

This looks good to me with OpenFL 8: