Breath meter

When a player's head is under Water, a Breath Meter appears in the upper-right corner of the game screen, representing the time the player has until they begin drowning. The Meter consists of ten air bubbles that fade and disappear gradually, as long as the character's head is submerged. When the Breath Meter is depleted, the player begins to drown and health is depleted. The Breath Meter refills quickly when the player emerges from liquid.

For breathing purposes, the player is considered "under water" when the pixel right above their eye is under water. This roughly correlates to just a pixel above where the water will be if the player stands in two full tiles of water with a tile of air in the third tile they occupy. Half-blocks can leave players drowning. (In older, and console versions, this was actually the very top pixel of the head. It was changed to prevent players from drowning when their head bumped water-filled blocks.)

If the Fish Bowl is worn in the equipment slot, the Breath Meter appears because the player's head is underwater. Breathing equipment and potions can still be used to counter this effect.

Breathing time
The Breath Meter's duration changes depending on which breathing equipment or potions are used. Times shown below are in real-world time (not game time):


 * Without equipment, the breath meter lasts around 22 seconds.
 * With a Breathing Reed, breathing time is doubled to 44 seconds.
 * While wearing a Diving Helmet, the breath meter lasts 1 minute 34 seconds.
 * When both the Breathing Reed and Diving Helmet are used, the breath meter lasts 3 minutes and 8 seconds.
 * Neptune's Shell eliminates the Breath Meter while under Water, making breathing time unlimited.
 * The Gills Potion eliminates the Breath Meter while under Water while the buff is in effect (2 minutes total).

Bugs
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