Fix premultiplied alpha

[SpartanJoe193]

The problem id that every time I have to convert a tiff to PNG (I don't have access to a PC so no GIMP) the alpha is always premultiplied so inevitably my shaders get artifacts.

This is what one of the images' rgb should look like

[AntonPieper]

Hello, according to someone on stackoverflow, loading images using BitmapFactory (which is what we currently do) loads images with premultiplied alpha. PNG images themselves are not premier plied. So using a different loader would fix this.

Edit:

After some of my own research, starting with API level 19 (we use 21), BitmapFactory.Options does support loading images non premultiplied. So, a fix should likely be adding another /// some-key-that-says-premultiplied:false thing and depending on that, set the BitmapFactory.Options#inPremultiplied flag.

[SpartanJoe193]

So it's an Android issue?

[AntonPieper]

It's a bug that's here because the app originally targeted an API level that didn't have the needed flag. I can't think of a shader that would want the color data to be premultiplied (unless they load a texture that already has premultiplied alpha), so I think it makes sense to always load textures without automatically premultiplying the alpha (no special key needed). I can draft a PR for that :)

[SpartanJoe193]

Late rply. Thank you, I'm looking forward to it.

[SpartanJoe193]

It's a bug that's here because the app originally targeted an API level that didn't have the needed flag. I can't think of a shader that would want the color data to be premultiplied (unless they load a texture that already has premultiplied alpha), so I think it makes sense to always load textures without automatically premultiplying the alpha (no special key needed). I can draft a PR for that :)

Any update on this version @AntonPieper?