Forums | NoesisGUI

"We have been investigating this issue and found an explanation. Problem is that Unity doesn't use premultiply alpha (blogs.msdn.com/b/shawnhar/archive/2009/11/06/premultiplied-alpha.aspx) and NoesisGUI pipeline is entirely based in premultiply alpha. Premultiply alpha is the correct way to do the things.
Ideally the conversion from straight alpha to premultiplied alpha should be done at texture import time (as we do in Noesis), but there is no option to active it in Unity. The solution for you is doing in by hand. You have to multiply each color channel by the alpha channel."

using UnityEngine;

public static class TextureConverter
{
		public static Texture2D ConvertToPremultipliedAlpha(Texture2D source)
		{
			Color[] srcColors = source.GetPixels();
			Color[] dstColors = new Color[srcColors.Length];
			for (int i = 0; i < srcColors.Length; i++)
			{
				Color srcColor = srcColors[i];
				float a = srcColor.a;
				dstColors[i] = new Color(srcColor.r * a, srcColor.g * a, srcColor.b * a, a);
			}

			Texture2D result = new Texture2D(source.width, source.height, TextureFormat.ARGB32, false);
			result.SetPixels(dstColors);
			result.Apply();
			return result;
		}
}

    // texture is variable representing Texture2D
    var convertedTexture = TextureConverter.ConvertToPremultipliedAlpha(texture);
    // now you can use this texture in TextureSource
    var textureSource = new TextureSource(convertedTexture);

We are going to improve the documentation with all this and if you don't mind we are going to publish the source code to convert to premultiply-alpha in our github project: https://github.com/Noesis/noesisgui-contrib
thank!

Hi!

Can't you do the premultiplication in the source image itself? (in the .PNG for example, just before Unity creates the internal texture). That way you can use compression without any kind of problem.

Problem with not using premultiply alpha is that the results are not correct. You can find more information about it in internet, but basically without premult-alpha you get halos around the edges. What I don't really understand is how Unity still doesn't support this step at import time.

http://answers.unity3d.com/questions/98 ... -pngs.html

* First, using Photoshop to perform the premultiplication => no success