Foliage constantly Dynamic


I think that this is a bug (and if it is than this is huge). I am testing the foliage and it seems that it is always Dynamic. I am checking GPU Visualizer under Scene->BasePass->Dynamic . Without ANY light, baking with no light, Cast Shadow turned off on foliage I have like 11-12 ms in Dynamics. There is nothing else in the scene just the base box ground and some foliage. The material don`t have anything. I painted like 13k of small grass with just few polygons. Why there is so huge Dynamic ms ?


Could someone from Epic tell if this is normal behavior or a bug, please ?

Dynamic also accounts for movable static meshes. The foliage you have painted most likely has movable setting on so it’ll count it in the dynamic category.

It’s kinda hard to tell without any details, a lot of different stuff might contribute to that spike.
What exactly in your scene, what tool you’re using for instantiating the grass, how big is transparent part of meshes, material setup, static mesh setup
For example, if you have 13k of movable meshes containing 20 overlapping planes where 90% of pixels are transparent and all of them are shown on the screen then you will get that crazy rendering cost. Or something in material might cause this

Sure you would be correct but… I have nothing dynamic in the scene. Look at those screenshots. There is no Cast Shadow on light, no Cast Shadow on Foliage, no other meshes. Foliage is Static with No Shadow. This is just the basic scene with 1 foliage and almost nothing in the material. So where is the Dynamic coming from ? It put many foliage just to exaggerate the problem.

EDIT: Ok, I found what is causing it. Its the geometry. I found that my tesselation is ON. Besides of that I reduced the polys and it is way better. But it still doesn`t explain the “Dynamic” to me. It is little bit confusing for me. I was 120% sure that this has to do with Moveable objects or Dynamic shadows. It should be better explainde I think.



Oh, neat!
No wonder I was not able to reproduce this effect :smiley:
As for dynamic itself - I believe it’s not static/movable in particular, it’s more about dynamic lighting features. For example, if your static mesh support some sort of dynamic lighting(For example - you add movable light to the scene then your meshes will receive this lighting + it will contribute to specular reflection) then cost will increase. Basically it’s more low level then simple static/movable. I could be wrong about this though and this is just my interpretation of different UE4 optimization articles I found