Runtime Mesh Component

[Koderz]

This is going to be a long post since I’m replying to multiple people at the same time. (Sorry about being a slow response, combination of end of classes and then the holidays)

@Tomza;635422

I downloaded the big zipped folder (/tag/v2.0) and run the project. What to do know? Where’s the cut mesh feature? Do you have any movie on Youtube.?

I do not have any videos, and if I’m honest the docs are pretty lacking at this point, but that will hopefully change shortly! The slicer isn’t going to be in that release zip due to licensing restrictions from Epic. I hope to have a better solution to this eventually, but for now the best way to get it is via the marketplace. The next best way is to pull the RMC+Slicer from here and overwrite the RuntimeMeshComponent folder within the Plugins folder with what’s in that zip. I’m around the UE4 Discord pretty much all of my available time if you need help. Once you have either that version or the marketplace the ‘Slice Runtime Mesh’ function will appear in blueprint. You can also access it from c++. Also you’ll need to have a GitHub account linked to your UnrealEngine account and be logged in to view the link above.

@Mtimofeev;637645

Can anybody advice me on how to do a proper lighting with the runtime mesh component without taking a performance hit? I am unable to maintain 90fps in a oculus rift with Geforce 1070 after I turn on dynamic lights and shadows from a single directed light source with a very simple scene - an apartment with 2-3 rooms, where every room is an actor with 3 subComponents - floor, ceiling and walls - all of them are a single RuntimeMeshComponent, although the walls component has many different sections - 4 to 30, depending on the room topology, every section is a flat surface though. My meshes are procedurally generated once at a startup from a text file and never touched afterwards.

I’m aware of a few potential problems with how the RMC operates compared to the SMC that could be the cause of some of this. This is part of the reason I’m currently doing a ground up rewrite of the core of the RMC. Unfortunately though this will likely be a little while coming, but I’ll keep you posted on that.

@;637652

Just came across an Editor Crash related to CopyRuntimeMeshFromStaticMeshComponent Blueprint Node.
I run the node within the construction script. When the Input StaticMeshComp is empty the editor crashes.

Well that’s not good! Will look into that!

@housekiller;638348

Have you tried the difference with normal imported movable static meshes? Try optimizing such a scene first for VR performance, it’s not an easy feat making a game perform well in VR while still looking good.
I’m finding performance with procedural meshes to be surprisingly good but having lots of dynamic lights and objects will always be hard on the GPU and is not necessarily linked to procedural meshes (rather to all dynamic objects).

@Mtimofeev

There are some issues I’m aware of like I mentioned above where the RMC is slower than the SMC even for movable objects. I’m working on that with the new version. VR is indeed an interesting, and hard, thing to optimize for and even more so when you can’t take advantage of things like baked lighting. Unfortunately there’s not really a way to get that with runtime generated meshes.

@Mtimofeev;639815

I appreciate your reply. A similar scene with imported static mesh gives me steady 120+ fps. My scene is really very simple - it is just few rooms: walls, floors and ceilings, a single source of light (the sky light) and I’d assume there should be a way to get 90fps. What I think could be problematic is that every room is currently an actor with single RuntimeMeshComponent that consists of a large number of sections. I have mistyped it in my OP, the RuntimeMeshComponent is rather constituted by 40-120 sections. But there are only 4-8 such components in the whole scene. Can this be a problem? Would it be better if these sections were instead separate actors? I absolutely need to be able to apply a material separately to each of the sections, so I either have to make them RuntimeMeshComponent sections or separate actors.

I know I already mentioned there being some known issues, but I’ll elaborate a little bit here… I would also be interested in talking to you on the UE4 Discord if you’re willing to learn more about your setup and see if there’s other things I’m not yet aware of.

Now, One of the main areas I’ve found out where the RMC can be substantially slower is shadows. The SMC pre-computes an optimized index buffer for shadows which reduces the number of vertices transformed on the GPU. This is something I plan to do more investigation on and if it really turns out to be of use I’ll likely add support for it in the upcoming version. Next it uses a single vertex buffer for all of it’s sections whereas the RMC doesn’t and instead has a vertex+index buffer for each section which can lead to more state changing. Also the SMC doesn’t use have color information in the vertex buffer if it’s not needed. The RMC is on its way to supporting that (actually the template vertex will let you disable it, but the engine won’t like it since the RMC doesn’t handle it correctly). There’s possibly some other things I’m not yet aware of but I’m still doing a broad and very detailed comparison of the SMC and RMC and how they operate. Some things the SMC does can’t really be done in real-time but some can, and will be.

Now to make you aware of some other potential pitfalls with your current setup… 40-120 sections isn’t by itself a bad thing but there are some major things to watch for. If you create/update any section marked with Infrequent Updates, it will resync ALL vertex/index data to the GPU. Same goes with changing shadowing on those sections. If they’re all Average/Frequent it won’t resync all but I believe changing materials will force a total resync as well. If these are spread out over a large area you’ll likely want to break them up due to culling not being able to remove some of them based on them all having the same bounding box. Furthermore each section constitutes a draw call (actually more if you count shadows or other things like planar reflections or scene captures) so especially in VR you want to minimize that as much as possible while also being mindful of not making too few meshes that are so large as to bottleneck you the other way. While it’s a little more complicated than this, if you’re CPU bound you probably have too many sections.

@Mtimofeev;640239

A single sun is what I am using, yep. And with the same amount of static meshes set to movable I had way better performance, so it’s something about the amount of runtime meshes I suppose.
As far as I know, there is no way to have a dynamic array of components in any actor (or is there?), hence also no way to create a single actor with a dynamic array of RuntimeMeshComponents, so the only way to split the big meshes is to split them into multiple actors. That is, from one actor with one component with 100 sections I will move to 100 actors with one component with one section each. I had tried it with the UEs ProceduralMeshComponent and haven’t noticed any performance difference, but maybe this will work better with the RuntimeMeshComponent.

You can have multiple components as a part of an actor, you can only have one RootComponent. You can add children of the RootComponent though. You can add them and then query them, or you can add them and store the pointers to them as well (make sure they’re decorated with UPROPERTY if this is in C++) This honestly sounds like part of it is from some of the known issues but unfortunately the version to fix much of this is likely a couple months out.

@patlj09;640276

Hi ,
Just came across this component, and it seems to be what I need. The PMC should be enough for me, but I can’t seem to figure out how to have it accept materials in the editor.

This is a bit of a newbie question, are there any build instructions for Mac OS? What is the best way to integrate into your project? Cross platform?

thanks / Patric

To add materials, you have to use the ‘+’ button to override them and add them. They only show up automatically if the sections exist in the editor (created in construction script)
For Mac OS, I haven’t directly tried to build it due to not having a Mac but to my knowledge you should be able to add it as a plugin within the project and build as normal. The marketplace also appears to have it built for Mac so it should build correctly. The marketplace also has the current version, including the slicer so that might be easier to install than trying to manually build it.