The bug

When a model contains an element that exists outside of the 0-16 bounds (-16-32 is valid) the default UV mapping will not be capped at 0-16, causing texture atlas bleeding. The problem in this report is specifically the auto-UV mapping, for UV provided out of range, see MC-236285.

How to reproduce:

1. Replace the minecraft:block/cobblestone model in a resource pack with the following:

   {
   	"parent": "minecraft:block/block",
   	"textures": {
   		"all": "minecraft:block/cobblestone"
   	},
   	"elements": [
   		{
   			"from": [ -16, -16, -16 ],
   			"to": [ 32, 32, 32 ],
   			"faces": {
   				"up": { "texture": "#all" },
   				"down": { "texture": "#all" },
   				"north": { "texture": "#all" },
   				"south": { "texture": "#all" },
   				"west": { "texture": "#all" },
   				"east": { "texture": "#all" }
   			}
   		}
   	]
   }

   Notice that no UV mapping is provided, so it used auto-mapping.

2. Load the resource pack
3. Place a cobblestone block in a world
4. Notice how the 9 textures are shown with cobblestone in the center
   

The fix

Either one of the following:

• Deploy the second fix option for MC-236285. (Preferred fix)
• Make auto-uv mapping get the size of the face, and offset, like it does now, but then clamp it between 0 and 16 (offset into the area before cutting the size down so that elements fully outside the 0-16 range do not get a 0 wide/tall UV).