Look Detection

Introduction ​

Sourced by the Bedrock Commands Community (BCC) Discord

Credits: @AjaxGb

This command-technique allows you to detect when a target looks at a player/entity/coordinate and subsequently run your desired commands.

Command ​

execute as <target> at @s anchored eyes facing <entity | coordinate> positioned ^^^1 positioned ~~-1.62~ rotated as @s positioned ^^^-1 if entity @s[r=0.2] run <command>

Visualisation:

Note: This is a rough visual representation, not precise measurements.

Command Breakdown:

• as <target>
  • sets the execution target. Example:
    • as @p (closest player)
    • as @e[type=zombie] (all zombies)
• at @s
  • sets the execution position to the target's feet.
• anchored eyes
  • brings the execution position up to the target's eye level.
• facing <entity | coordinate>
  • sets the execution rotation facing an entity or coordinate. Example:
    • facing 0 0 0 facing coordinate: 0,0,0.
    • facing entity @e[type=pig,c=1] eyes (facing eyes of nearest pig)
    • facing entity @e[type=cow,r=30] feet (facing eyes of cows in a 30 block radius)
    • facing entity @e[type=zombie] feet (facing feet of zombies)
• positioned ^^^1
  • from previous point, pushes the execution position 1 block forward in the direction of the entity/coordinate.
• positioned ~~-1.62~
  • lowers the execution position back to that of the player's feet on the y axis. Which is 1.62 blocks below eye level.
  • Note: Due to the MCPE-165051 bug, you cannot use anchored feet in place of this.
• rotated as @s
  • Reverts the execution rotation to that of the target.
• positioned ^^^-1
  • from previous point, pushes the execution position 1 block backwards from the direction the target is facing.
• if entity @s[r=0.2]
  • checks if the target is within a 0.2 block radius from the execution position. ie., check if after this back and forth we've arrived roughly back at the target's feet position.
  • To increase or decrease the tolerance for what is considered "close enough", change the 0.2 distance argument.
    • it needs to be between 0.2 and 2, as 2 basically means you can look in the opposite direction and it's still "close enough". So, realistically, you want to most likely stay well below 1.
  • To calculate the exact viewing cone angle, see below.

Examples:

1. Run a /say command when looking at the eyes of cows or sheeps tagged 'target':

execute as @a at @s anchored eyes facing entity @e[type=cow,tag=wiki:target] eyes positioned ~~-1.62~ positioned ^^^1 rotated as @s positioned ^^^-1 if entity @s[r=0.2] run say hello cow!
execute as @a at @s anchored eyes facing entity @e[type=sheep,tag=wiki:target] eyes positioned ~~-1.62~ positioned ^^^1 rotated as @s positioned ^^^-1 if entity @s[r=0.2] run say hello sheep!

2. Run a /say command when looking at the position (10, 20, 30) or (6, 7, 8):

execute as @a at @s anchored eyes facing 10 20 30 positioned ~~-1.62~ positioned ^^^1 rotated as @s positioned ^^^-1 if entity @s[r=0.2] run say hello block!
execute as @a at @s anchored eyes facing 6 7 8 positioned ~~-1.62~ positioned ^^^1 rotated as @s positioned ^^^-1 if entity @s[r=0.2] run say hello block!

Alternative Structure:

execute as <target> at <coordinate | entity> facing entity @s eyes positioned as @s positioned ^^^1 rotated as @s positioned ^^^1 if entity @s[r=0.02] run <command>

If you don't need to detect the target looking at the eyes of an entity but their feet or a coordinate, you may use this structure which negates the need for the anchored eyes instruction as the execution position begins from the entity/coordinate rather than the target.

Calculate Viewing Angle ​

To approximate the distance/radius you want to use based on your viewing angle, you can use the following formula, where α is the angle that you want this method to trigger inside of, left and right of the target:

r = 2 * sin ( α / 2 )

or, the inverse to calculate what viewing angle a certain radius / distance (r) value will give you:

α = sin^(-1) (r / 2) * 2

Note: Depending on your calculator, you'll need to convert from radians to degrees.

With the above calculation, the example value of r=0.2 leaves us with roughly a 12° angle by which we can miss the exact target in either direction and still have it considered "close enough."