Blurry Item Textures in the Player Inventory

The items of my resource pack are blurry and distorted (they are not meant to be). I have read this bug report before and the last comment (I couldn't comment on that bug; would have) read "...the block model format has changed recently, you have to adapt the resource pack to the current snapshot." I am unaware of how to do that. Posting this was my last resort.