How to render the most amount of rats as possible?

[jak6jak]

I want to render a lot of rats at once. This is my post asking for help on how I could do that. So far I have 2,500 rats rendered and animated at once with about 5-10 FPS I want to increase that number quite a bit. Here is the public repo I am working in: https://github.com/jak6jak/hairyrat

The rats I am rendering are right now very low poly:

Here is an image of xCode profiling. I am using 16 draw calls and about 6ms per frame

[jak6jak]

Here is tracy debug:

[torsteingrindvik]

Looks like very long "par for each" calls, maybe it's just because the scene has 600k+ entities.
Do you know why the scene has that many entities?

[jak6jak]

It's most definitely the model I am using. Here is what the model's outline looks like in blender:

[torsteingrindvik]

I'd suggest you try the animated model stress test: cargo run --release --example many_foxes -- --count 2500, I get >100 FPS there. In fact I can go up to 25k foxes before I get the same FPS as your repo.

If you swap out the rat in your repo with the fox the entity count is a lot lower, and FPS is better. But probably try comparing the stress test code to yours to see if there are other tricks.

[jak6jak]

hmmm I get 71FPS with many foxes. I will try profiling that with tracy to see the difference

[jak6jak]

Here is a more zoomed in tracy profile. it seems animation targets is where most of my CPU is going to.

[nicopap]

Take what I'm about to say with a grain of salt: it's been a while since last time I played with the engine.

How many poses do you have? Is it possible to bake the pose as a morph target? Or is your animation dynamic? If you can do with two poses, you can use morph targets. In blender those are called "Blend shape keys", you can save the pose as a morph target, and remove the skeleton rig when saving to gltf by toggling the options when exporting.

In terms of performances, it should be technically much better. You can then eliminate all entities related to the skeleton, and avoid all the math related to animations. Thought it might not, honestly 🙈 it is much more heavy on the GPU. But given the size of the models, it might do a difference.

[janhohenheim]

For faraway rats, look up LODs and impostors. LODs are even more low-poly models that are used at a distance, and impostors are just 2D billboards that are used at max distance for extremely cheap rendering
Edit: I see you already use an LOD0, so you already know about that part ;)

[jak6jak]

Would the implementation of the following issue help with the slowness of animate_target? #11633

[jak6jak]

Okay today I learned about Vertex Animation Textures https://stoyan3d.wordpress.com/2021/07/23/vertex-animation-texture-vat/ I think this will fix most of my performance issues