Screen Blend Mode not looking right

[colourclash]

Has anyone also noticed that the Screen blend mode while using the WebGL renderer looks more like an additive blend?
I've attached a test image to demonstrate the problem.
What I've done to fix it in the meantime (which to be honest is a blind guess) is to change this line in WebGLRenderer.js
this.blendModes[CONST.BLEND_MODES.SCREEN] = [gl.SRC_ALPHA, gl.ONE];
to this
this.blendModes[CONST.BLEND_MODES.SCREEN] = [gl.ONE, gl.ONE_MINUS_SRC_COLOR];

 

[ivan.popelyshev]

And another moment of fame for me!

There're pull requests about it: https://github.com/pixijs/pixi.js/pull/2321 . It switched gl.SRC_ALPHA to gl.ONE if texture has premultiplied alpha. And second parameter is gl.ONE_MINUS_SRC_COLOR and I think it is correct.

Build is here: https://dl.dropboxusercontent.com/u/46636530/pixijs/blendMode/pixi.js

Test it please, I need a feedback.

[colourclash]

Hi Ivan,
Testing with your build, the screen blend now looks identical to the photoshop version 

[ivan.popelyshev]

Can you please add "texture.baseTexture.premultipliedAlpha=false" in your demo, before you render it? We need to test that too.

[colourclash]

okay.. it looks slightly lighter now. I'm just using a standard .png output from photoshop which I guess is not pre-multiplied? 

EDIT: actually it looks identical to the previous output!

[ivan.popelyshev]

It looks the same. Actually, it cant be different , because your texture has no alpha component at all.

The only major thing we changed is the second parameter, and now its corrected.

[colourclash]

So, testing with an image containing alpha I get:

tex.baseTexture.premultipliedAlpha = false;

 

[colourclash]

tex.baseTexture.premultipliedAlpha = true;

 

[ivan.popelyshev]

And which one is correct? Can you plese change "PIXI.autodetectRendere" to "new PIXI.CanvasRenderer" ?

[colourclash]

For my purposes the second output above is what I need. I did some tests with a non-premultiplied image and setting baseTexture.premultipliedAlpha to false which to my eyes didn't look the way I would expect - I normally just go with pre-multiplied images so perhaps someone who is using non-premultiplied textures can chime in here.
When switching to canvas renderer, with baseTexture.premultipliedAlpha set to true or false, they both look like the second image above.

[ivan.popelyshev]

That's very strange. I'd like to debug the variant with premultipliedAlpha=false; , can you please upload it to codepen.io?

I can do that too, but just to save time..