Sensors

A Sensor is a Hardmode mechanism that emits a signal under specific circumstances. There are 7 different types of sensors, split into 2 sub-categories: Logic Sensors, and Liquid Sensors.

There are 3 different Logic Sensors:
 * Logic Sensor (Day) which emits a signal when night turns to day.
 * Logic Sensor (Night) which emits a signal when day turns to night.
 * Logic Sensor (Player Above) which emits a signal when a player enters the area above it, and emits another when the player leaves the area above it.

There are 4 different Liquid Sensors:
 * Liquid Sensor (Water) which emits a signal when submerged in water, deactivates otherwise.
 * Liquid Sensor (Lava) which emits a signal when submerged in lava, deactivates otherwise.
 * Liquid Sensor (Honey) which emits a signal when submerged in honey, deactivates otherwise.
 * Liquid Sensor (Any) which emits a signal when submerged in any liquid, deactivates otherwise.

Player Above Sensor
It has a 5 blocks wide and 10 blocks tall detection zone, although it is actually about 1-2 pixels bigger than that.

When a player moves into the zone, it sends a signal. When a player exits the zone, it also sends a signal.

Note: In multiplayer, if one player moves into the zone, and then another enters the same zone while the first player is still in the zone, the sensor will not send another signal, making it useful for automatic doors in multiplayer (where multiple players may pass the same door). The Player Above sensor will also trigger on the position of dead players until they respawn. This fact may be relevant in situations where the player is likely to be killed near the sensor.

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