Talk:Java Edition 15w40a

Pathfinding
I dug into the pathfinding code a little bit. A position can have one of the following states: As far as logic goes, #1, #5, and #6 are "never go here" (weight -1); #2, #3, and #4 are "ok to go here" (weight 1); #7, #8, and #10 are "avoid this" (weight 8); and #9 and #11 are "really avoid this" (weight 16).
 * 1) Impassable.
 * 2) * Most blocks made from a movement-blocking material. Exceptions are banners, signs, open fence gates, and pressure plates.
 * 3) * Walls, fences.
 * 4) * Snow layers stacked 5 or more deep (but the mob might jump on it).
 * 5) * Any wooden door for villagers at night.
 * 6) * Closed wooden doors for entities that can't open/break them.
 * 7) Ok.
 * 8) * Anything that's not one of the other categories.
 * 9) Kind-of ok.
 * 10) * Open trapdoors within the position, or the position is completely over air, water, or lava.
 * 11) Closed trapdoor within position.
 * 12) Rails, unless the mob is already on or just above rails.
 * 13) Lava, unless the mob is already in lava.
 * 14) Water.
 * 15) Fire at ground level adjacent to the position.
 * 16) Fire within the position.
 * 17) Cactus at ground level adjacent to the position.
 * 18) Cactus within the position.

But sometimes the weights change: As far as changes since previous versions, it looks like they added the "avoid" states where previously it was just "ok to go here" or "never go here", and the cactus bits, and removed the EntityAITempt routine effectively setting #7 to "ok" since the default is now "avoid" rather than "never". I don't know if someone can turn all that into something useful. Anomie x (talk) 23:55, 30 September 2015 (UTC)
 * Blazes change #8 and #9 to "ok to go here" (weight 1).
 * Blazes change #6 to "avoid this" (weight 8), rather than "never go here" (weight -1).
 * Blazes and endermen change #7 to "never go here" (weight -1).
 * Chickens, mobs leashed to an entity, and tamed mobs following their owner change #7 to "ok to go here" (weight 1).