4.16 Preview, Foliage actor instances are all still hit by lights and recompute shadows

And the performance is god awful.

This has been occurring since 4.14.

Is there any way to split up foliage so this does not occur?
Is there a hacky workaround?
Is there a fix incoming for this issue?

Hey KMcPherson,

Would you be able to explain in better detail the problem you are experiencing, and provide me with a way to visualize it on my end?

Thank you,

If one goes into the foliage tool and adds a number of different foliage actors…trees, grass, etc, and then paints the terrain with them, one monolithic foliage actor is created ( clicking upon it will select all the foliage instances ). And because it is one Actor…lights that hit any part of the actor attempt to light and shadow all the instances. So, for example, if I set up a number of dynamic lights around the eastern edge of a small forest, the entire forest of instances, even those well outside the applicable range of the light, will execute light and shadow calculations…resulting in a massive drop in performance. This was not the case in 4.13, but became true starting in version 4.14. This issue remains in the 4.16 preview release as well.

Paint about 30,000 foliage instances into a larger level, and place about 200 static lights throughout the level and you should start to see the performance hit. We have about 300,000 foliage instances in a level where this issue is very prevalent. Also, have a skylight. We were not having a problem at all in version 4.13 and before.

Hey KMcPherson,

So I ran a test on my end using the engine content, but attempting to recreate this performance issue without screenshots or comparison is really tough. You have a lot in your scene that is not accounted for, so saying there is a performance hit with 30,000 instances and 200 static lights is fairly broad reaching.

What would be helpful is for you to provide me with some comparative screenshots of the scene performance well in 4.13 and then the poor performance in a later engine version. This will give me a gauge so I can reproduce the issue on my end. Could you also provide me with your computers specs i.e ‘dxdiag’ so I can add that information to the bug report if necessary?

Thank you,

We are going to get you packaged debug versions of 4.13 and 4.16 with one of the problem levels so you can see exactly what is going on. Its lighting / shadow calcs happening across the foliage actor instance ( all of them ), which started in 4.14. Thanks.

Sounds good. I’ll wait for the project.

I realized yesterday that I am assisting you and your team on our private UDN so we can continue troubleshooting there. I am going to mark this post as resolved for tracking purposes.

Thank you,