I am looking for a filter that can be used to generate pattern, and repair pictures via alpha approach. It has to use alpha, and fills in the alpha. I swear I seen this filter somewhere when I was bored. It’s not in inpaint last time I recall.
What sorts of repairs are you talking about? Could you be more specific?
Pattern repair specifically. I was testing G’MIC filter on a game leaf texture which contains transparency, and it somehow fills up the missing area consistently as if the veins of the leaf are revealed. I’m not sure if that helps. It’s like inpaint(patch-based), but instead it used alpha information.
I have no idea. Many filters take advantage of inpaint and derivatives. Perhaps the author of the unnamed filter will let you know. 
PS When you look at the reference for inpaint, you would see that it takes a mask as input. Hint: each line is a possible parameter combination. In your case, the command in question is looking at the alpha rather than a mask layer.
inpaint (+):
[mask]
[mask],0,_fast_method
[mask], _patch_size>=1, _lookup_size>=1, _lookup_factor>=0, _lookup_increment!=0, _blend_size>=0, 0<=_blend_threshold<=1, _blend_decay>=0, _blend_scales>=1, _is_blend_outer={ 0 | 1 }