I was testing the performance of a prototype scene, when I realized something related to draw calls and how they are represented in the stats.
The scene is filled with 252 static meshes (simple bevelled cubes with 44 nanite vertices each one), disposed as a matrix of 6 different material instances of the same master material. The drawcall stats look like the picture shown below (using stat rhi).
Well, so my doubt came when I decided to remove all the cubes except the front row, and of course I expected a huge draw call decrease. But when I checked out the stats again I saw the number was exactly the same, as it is visible in the images below).
More info that could be useful, I have downloaded RenderDoc, and it seems it is launching one draw call per material instance, is it right or I am reading it wrong? (I’m pretty new with this kind of debugging)
Did you figure out this problem?
Im having the same debate, i am making a game in ue5 and i have around 1500-2000 draw calls some areas being 5000+ these are all single assets such as say a table with plates,knifes,forks,ect all single assets making up alot of draw calls. So i know i can merge these into one static mesh bringing all assets to one draw call(becauae it ia now one mesh not 20. But sometimes the table will deform once merged with other actors. My plan is to merge as much as possible to lower draw calls. However you make it seem in your picture that any asset that is duplicated does not add an extra draw call?
I tried different approaches for this particular issue.
Firstly I tried to merge the meshes as you say and see if it did the job. But it was not the case because I had weird geometry deformations that you spotted as well. Besides, if those props were distant enough, the lumen projection cards included the entire group losing a lot of detail and generating indirect lighting artifacts (unfortunately I don’t have access to that exaple anymore so I can’t post it here).
However, I finally figured out that Nanite meshes with the same material are treated as one drawcall per group of meshes, so my final approach were to try to unwrap as much objects as possible in the same texture map, for example in your case I would try to include plates, knives, forks, spoons, etc in the same texture set so they translate into just one drawcall, even if you place 100 of them.
As I mention, this last approach is just valid if you use Nanite meshes, but if I remember correctly, Unreal devs said in one Q&A streaming that there’s no reason to not use Nanite meshes, as it is very useful even for props that are not million polygons and it works in tandem with Lumen system.
