How to get the closest player another player is directly looking at?

Well my question is in the title. The range is 10 blocks.

I think you have to do some math with vectors, range checking, getting players of the current world. Just some notes. Please help me!

 

Actually, Bukkit kindly created a method just for this kind of thing. In Player, there is a method called "getLineOfSight" and it returns a List of Blocks that the player is looking at, in order from closest to furthest. You can then iterate through the List until the Block is 1 meter(or whatever distance you'd like) from any Player.

 

Get all the players in a cerain radius and then calculate the angle or dot product to each of them to get the nearest player the player is looking at.

I can give you the code for that when i am at home.

Edit: Okay, here you go:

Code:

private Player getTarget(Player from) {
        assert from != null;
        // SOME FIXED VALUES (maybe define them globally somewhere):
        // the radius^2:
        double radius2 = 10.0D * 10.0D;
        // the min. dot product (defines the min. angle to the target player)
        // higher value means lower angle means that the player is looking "more directly" at the target):
        // do some experiments, which angle / dotProduct value fits best for your case
        double minDot = 0.98D;
     
        String fromName = from.getName();
        Location fromLocation = from.getEyeLocation();
        String fromWorldName = fromLocation.getWorld().getName();
        Vector fromDirection = fromLocation.getDirection().normalize();
        Vector fromVectorPos = fromLocation.toVector();
 
        Player target = null;
        double minDistance2 = Double.MAX_VALUE;
        for (Player somePlayer : Bukkit.getServer().getOnlinePlayers()) {
            if (somePlayer.getName().equals(fromName)) continue;
            Location newTargetLocation = somePlayer.getEyeLocation();
            // check the world:
            if (!newTargetLocation.getWorld().getName().equals(fromWorldName)) continue;
            // check distance:
            double newTargetDistance2 = newTargetLocation.distanceSquared(fromLocation);
            if (newTargetDistance2 > radius2) continue;
            // check angle to target:
            Vector toTarget = newTargetLocation.toVector().subtract(fromVectorPos).normalize();
            // check the dotProduct instead of the angle, because it's faster:
            double dotProduct = toTarget.dot(fromDirection);
            if (dotProduct > minDot && from.hasLineOfSight(somePlayer) && (target == null || newTargetDistance2 < minDistance2)) {
                target = somePlayer;
                minDistance2 = newTargetDistance2;
            }
        }
 
        // can return null, if no player was found, which meets the conditions:
        return target;
    }

Edit2: Changed it to prioritize a smaller distance rather than a smaller angle for multiple potential targets.

Edit3: Fixed, to only check players in the same world.

 

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Thanks!