[1.12.2] Left click in air while holding item

[ProspectPyxis]

I want an item to do something when you left click it while pointing at the air. How would I do this? I tried subscribing to onEntitySwing, but that event seems to also fire even if you're pointing at a block or entity. I also tried checking if the player is looking at anything with Item.rayTrace, but the method always returns null somehow.
One way I've seen is subscribing to a clientside event, but from my understanding that would require a packet, and I'd like to limit that if possible. Is there any other way, or is that the best way?

[desht]

Get over your fear of sending packets.  The server is never aware of a "left-click empty" event - that's even mentioned in the javadoc for the PlayerInteractEvent.LeftClickEmpty event. Your only option if you want to inform the server is to listen for that event on the client and send a packet.

[ProspectPyxis]

I mean, I already know how to send packets, I'm just not sure about the performance impact which, looking back, shouldn't really be that big even combined with the few other packets already in the mod. Oh well, I'll be looking into the event then.

[desht]

The simple number of different packets in your mod has zero impact on performance.  What does impact performance is ensuring you don't send packets unnecessarily, and that you encode information in the packet efficiently - don't send more data than is needed to convey the message (extreme & simplistic example: don't use a double to send a boolean value).

• Only send packets when you know the other side needs the information.
• Encode any data needed properly, e.g. don't use NBT for network data, use the smallest data type that fully describes the information you're sending.

In your case, a simple packet sent when a player does a "left click air" action is no big deal. It doesn't even need any extra data encoded in it - whenever the server receives such a packet it has all the information it needs: "player X just did a left click air".

 

[ProspectPyxis]

So since I want to only do something with the item if you're holding it, I'd check if the player is holding the item first before sending the packet, correct?

[DavidM]

What exactly are you trying to achieve? Empty left click swing or left click and hold?

I can’t read.

 

Yes. You should check if the player is holding the item (however a hacked client can easily send a false packet even if the item is not held in hand; you should also perform a check on the server side).

Edited March 31, 2019 by DavidM
to -> the

[desht]

16 minutes ago, ProspectPyxis said:

So since I want to only do something with the item if you're holding it, I'd check if the player is holding the item first before sending the packet, correct?

Check on both sides: on the client so you're not sending unnecessary packets, and on the server because rule #1 of multiplayer gaming is don't trust the client.

[ProspectPyxis]

That makes sense. Thank you for your help!