Tripwire Hook

A tripwire hook is a block that can be used to detect entities (players, mobs, items, etc.) when part of a tripwire circuit is passed through.

Natural generation
Four tripwire hooks are generated naturally in each jungle temple.

Breaking
To remove a tripwire hook, it. Tripwire hooks can be broken instantly using any tool, or without a tool.

A tripwire hook is also removed and drops itself as an item if:
 * its attachment block is moved, removed, or destroyed
 * water flows into its space $$
 * a piston tries to push it or moves a block into its space

A tripwire hook is destroyed without dropping itself as an item if lava flows into its space.

Fishing
Tripwire hooks can be obtained as a "junk" item from fishing.

Usage
Tripwire hooks can be used as crafting ingredients or as redstone components.

Crafting ingredient
Tripwire hooks can be used to craft trapped chests and crossbows.

Redstone component
A tripwire hook can be used to detect mobs, items, and other entities over a large area.


 * Placement


 * To place a tripwire hook, use the control.


 * A tripwire hook can be attached to the side of any full solid block, with the inexplicable exception of blocks of redstone and observers.


 * In order to function correctly, a tripwire hook must be part of a "tripwire circuit": a straight line of blocks consisting of a block with a tripwire hook attached to it, a "tripwire line" (1 to 40 blocks of tripwire), and a second tripwire hook attached to another block, with both tripwire hooks facing the tripwire.


 * To place tripwire, use the control with a string. Tripwire in a valid tripwire circuit has a short hitbox (0.09375 or 3/32 blocks high, with the bottom 0.0625 or 1/16 blocks above the block below), while tripwire not in a valid tripwire circuit has a taller hitbox (0.5 blocks high, bottom not raised).


 * A tripwire hook in an invalid tripwire circuit appears "folded", while a tripwire hook in a valid tripwire circuit appears extended straight. Tripwire lines from separate tripwire circuits can be placed next to each other (in parallel), above each other, and even intersecting each other.


 * Activation


 * A tripwire hook in a valid tripwire circuit activates when certain entities (players, mobs, items, etc.) intersect the tripwire hook's tripwire line "hit box" (but not the tripwire hook itself), and deactivates when all entities leave or are removed from the tripwire line.


 * Entities that cannot activate a tripwire circuit include thrown potions, some arrows, fireworks, thrown ender pearls, and thrown eyes of ender.


 * A tripwire hook also activates for 5 redstone ticks (0.5 seconds, barring lag) when any of its tripwires are destroyed, except when shears are used to destroy the tripwire.


 * Breaking the tripwire hook, or breaking the block it is attached to, does not generate a pulse.


 * Behavior


 * While active, a tripwire hook appears to move downward and it:
 * powers any adjacent redstone dust to power level 15, including beneath the tripwire hook
 * powers any adjacent redstone comparators or redstone repeaters facing away from the tripwire hook to power level 15
 * strongly powers its attachment block to power level 15
 * activates any adjacent mechanism components, including above or below, such as pistons, redstone lamps, etc.


 * Tripwire produces no power itself, but its state change can be detected with an observer.


 * Although destroying tripwire with shears cannot activate a tripwire hook, it changes the tripwire hook's block state (its "attached" state from  to  ), which can be detected with an observer.

Trading
Master-level fletcher villager have a $2/3$ chance to buy 8 tripwire hooks for an emerald as part of their trades in Java Edition, and always offer the trade in Bedrock Edition.

Block data
In Bedrock Edition, a tripwire hook's block data stores its orientation, connection status, and activation status: