Hello,
I’m working on a bigger project for which I made a Bluprint which uses CSV. Files to build structures with HISM in the construction script. Since I doesn’t make sens to place this blueprint multible times in my scene for every single CVS file I have, I programmed it so that this BP can have multible Files which you can use tu build up larger structures.
Now when the structure gets to large and I try tu Build Lightning I get the warning: “Large actor receieves a pre-shadow and will cause an extreme performance hit unless bCastDynamicShadow is set to false”
I don’t know how to fix this problem since I want to use Dynamic Lightning whith these structures.
Any suggestions?
Hi 12erplays,
Are any of your meshes large? It’s usually the meshes, breaking them into smaller meshes will help.
I have 28 about 0.5 to 1m sized stone bricks but I combine them to make lare structures about 20- 50 m. or larger…
when you say combine - do you mean with MergeMesh? If so, split them back to their 0.5 → 1m meshes and add them as instances, if anything they’ll render faster anyway.
No I dont merge them together.
In Blender I place them by hand together to form a wall for example. then I use a script to output: Typ, Location, rotation and scale in to a .CSV-File, which I use an BP in UE4 to add instances to the HISM-Components.
The Structure as a whole gets then really large when I add multible CSV-Files in 1 BP together to form a 30m wall.
hmm - the only time I get that error is with large meshes. I have a bridge builder which constructs primarily with 1x1m blocks and the bridges can be large and long with no problems - unless I scale any of those blocks too large (say by 10x on any axis).
Maybe there’s a rouge transform in your csv file?
ok… Do you also use HISM with the Bridges?
and my english is not the best, what do you mean with “rouge Transfom”?
Yes I use HISMs - I use a HISM manager which has the HISMCs in a different, singleton actor (rdInst).
By rouge I was meaning a transform which had a large scale value, or referencing a mesh that is large.
ah ok, yeah that s also a good Idea to programm it like this. but I dont think this is causing the issue
no, as I said my stone bricks are between 0.5 and 1m in size and are only scaled to half or dubble theyre size.
also I dont get this error when my structure is only lets say 15m² in size
here you can see the individual segments I have which I combine to make larger structures
1 Like
I’ll restore my bridge project (I broke it converting to 5.3) and see if there is anything in the actor itself I’m changing and not remembering…
My projects still copying, but have you set the HISMCs mobility to Static?
No its on Movable
Aha! That will be the difference I’d say - set that to Static (you can still have movable lighting)
I did and it still puts out the message 
I also tried Stationary
and when I click on the “Docs” icon it cant find the Website with the UE documentary
My projects compiling now - I’ll take a look for any clues…
It looks like either your static mesh instances aren’t getting set to static correctly or it’s possible there is a problem with your meshes lightmaps.
I can’t tell If they are correctly set to static but there are no problems with the lightmaps.
However I found out that if I untick the Dynamic Shadow Option the warning message goes away, but thats not really what I want to do.
I get roughly the right shadow when I Dissable the Dynamic shadows on the HISM Bricks but ceep it on on the Mortar mesh underneath, which closly resambles the Structure.
This gives me sadly 2 issues:
- The Mortar mesh has to be a little bit smaller so it can fit inside so ther are gaps where Light can shine throu.
- I cant get the nice shadows on the wall cast from the indifidual stones that protrude a little bit from the wall.
Beautiful assets 
1 Like
Do you do this?
I did this and by clicking directly on the component to set it there to static but no effect