Training Stream - Alan Willard Power Hour - Dec 13th - Live From Epic HQ

Alan Willard is taking over the stream to drop knowledge and provide guidance from the perspective of a tech artist. Stay tuned for more details and make sure to watch live so you can ask your questions directly to Alan.

Tuesday, December 13th @ 2:00PM ET Countdown]


Alan Willard - Sr. Dev Relations Tech Artist


Very interesting!

Hopefully you’ll go over expense of each trace (maybe even show us with profilers), and then go over best practices of use, and if there should be a hard limit to their use and if so, what other options are there available to us!

Thanks for offering this… If time allows can you please cover:

#1. Tracing based on where the Player Camera is actually looking (equivalent of LOS Triggers in UDK).

#2. Trace limitations for fast moving objects moving in front of player controlled ship that’s also moving.

#3. Multiplayer… Any special considerations i.e. Replication / Multiplayer Origin-Rebasing catches etc.

What is already said + Traces ByChannel vs ForObjects <3

That’s great! I’m definitely tuning in to this stream. Would it be possible to cover the use of ray-casting for determining the degree of obstruction of audio sources?

Especially when it comes to which shape may best suit a specific task (e.g. why use a cylinder when a box would work). This may be specific to what you’re trying to achieve but a rough guide would be nice.

I hope so too since I’ve seen people claim on other forums/sites that now we have faster CPUs (than say back in UT '99’s day) trace expense doesn’t matter and to just go nuts with them, which I’ve never been 100% convinced about (from memory they were putting them all on Tick too).

Great stuff… well needed

I didn’t even know box traces existed before this post O_O

What this guy said.

[Question] Line ray traces done every tick. How expensive are these?

[Question] How to ray trace to navmesh. Example: You click on a location to teleport AI units there, but only if there’s a navmesh.


Will be watching this, thank you!

My Question: Any interesting ways to use traces with AI characters?

A thought I have about linetracing would be that when you aim at an enemy character, he can notice that you are aiming at him and strafe to the side (Like in StarWars BattleFront), I know that would be a different topic (regarding AI more than linetracing, but just leaving this here just in case)…

Updating every tic sometimes is unnecessary depending on what you need, how do you use a less frequent update?

Question: Can traces detect and return the

  1. speed
  2. color
  3. shape/silhouette-shape

of objects?

If so, would you be able to provide an example of how to accomplish this in blueprints?

yes please.

These raycasts make me think of a climbing system.Will we ever have an official tutorial for that?

[Question] How to manage materials/physical materials with raycast?

I second this. Knowing what trace to use and tracking down it’s cost in the profiler is super useful.

Hey y’all, sorry about the change in topic. Ian got terribly ill and luckily Alan was available to take over the stream.

Sorry to hear about Ian, Alan is just as fun though :slight_smile: Thanks for not cancelling!