Alpha and transparency question

[grit]

I have problem in Unity with sprites and transparent backgrounds. They have jagged edges.
I tried all the settigns Unity has to offer and everytime is the same. I'm left with conclusion that I need to set the sprites properly.

How to prepare the sprite in GIMP using this instructions? https://docs.unity3d.com/Manual/HOWTO-alphamaps.html

In PS

Quote:

1. Duplicate the layer
   
2. Select the lowest layer. This will be source for the dilation of the background.
   
3. Select Layer->Matting->Defringe and apply with the default properties
   
   1. Run the “Dilate Many” action a couple of times. This will expand the background into a new layer.
      
   2. Select all the dilation layers and merge them with Command-E
      
   1. Create a solid color layer at the bottom of your image stack. This should match the general color of your document (in this case, greenish). Note that without this layer Unity will take alpha from merged transparency of all layers.
      
4. Now we need to copy the transparency into the alpha layer.
   
   1. Set the selection to be the contents of your main layer by Command-clicking on it in the Layer Palette.
      
   2. Switch to the channels palette.
      
   3. Create a new channel from the transparency.
      
5. 
   Save your PSD file - you are now ready to go.