iiinova — where your digital self keeps evolving

Ghislain Girardot @ghislaingir.bsky.social · 02/05/2026

And yep, I have flicker issues upon swap. Still investigating :D Cheers.

Ghislain Girardot @ghislaingir.bsky.social · 02/05/2026

Anyway, this was an interesting experiment. Not sure how scalable that is but at least I get to see vertices moving with no WPO and Nanite isn't using its slow programmable rasterizer path🤷 I feel like we took ten step backwards in so many ways with UE5 'next-gen' renderer🙄Meh

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Ghislain Girardot @ghislaingir.bsky.social · 02/05/2026

This is all in all quite similar to Nanite Assemblies and how wind is applied to them. Except since wind simulation can be shared across instances, Epic uses buckets so similarly oriented trees can reuse the same transforms. Big perf win. Not something you can do for interaction.

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Ghislain Girardot @ghislaingir.bsky.social · 02/05/2026

Instance bounds colliding > swap activated > instance scale 0 > each assembly is now individually rendered as a particle and sample a custom transform buffer. Energy close to 0 ? swap deactivated, particles scale to 0, instance scale back to normal

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Ghislain Girardot @ghislaingir.bsky.social · 02/05/2026

Each 'assembly' is a particle rendered via Niagara's experimental Nanite Renderer. The assembly transform buffer is computed on the CPU by walking up the tree hierarchy described in the data asset and using world-space angular spring constraints.

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Ghislain Girardot @ghislaingir.bsky.social · 02/05/2026

Niagara is used to spawn a bucket of 2048 particles. I use a single Nanite Renderer with 5 meshes (one for each assembly). Particle's mesh size is 0 at first (culled) and reads from a custom DI to get its transform from a custom assembly transform buffer.

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Ghislain Girardot @ghislaingir.bsky.social · 02/05/2026

Foliage tool is used to paint Nanite-enabled hierarchical instances. Upon overlap with collider, foliage instance's scale is set to 0. This technique is still widely used to swap static instances with physically-driven skeletal meshes. Same principle here, but not quite.

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Ghislain Girardot @ghislaingir.bsky.social · 02/05/2026

I'm using the same concept as Nanite Assemblies Foliage. My tree is an 'assembly'. A JSON is exported from Blender and read in UE to construct a Data Asset describing the foliage's initial hierarchy, assemblies & colliders.

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Ghislain Girardot @ghislaingir.bsky.social · 02/05/2026

Nanite Programmable Path seems too costly to consider WPO for the most basic things... Uh, I don't like it. Feels like everything I'm tempted to do as a tech artist is no longer an option. Moving vertices used to be cheap :( So here's a hacky NO-WPO prototype 🧵

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Ghislain Girardot @ghislaingir.bsky.social · 22/02/2026

Thanks Christian, much appreciated! I'm joining Blue Twelve, the team behind Stray :)

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Ghislain Girardot @ghislaingir.bsky.social · 21/02/2026

Thank you for the past five (or so) years. It’s been a pleasure discussing with each and every one of you, and I’m truly humbled by your support and generosity 🙏 Much love, Ghislain

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Ghislain Girardot @ghislaingir.bsky.social · 21/02/2026

I’ll also try to release as many of my remaining WIP projects as I can tomorrow on Patreon. www.patreon.com/c/GhislainGir

patreon.com

creating educational UE projects and a video game!

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Ghislain Girardot @ghislaingir.bsky.social · 21/02/2026

My Patreon will remain active, as it contains 5 years of work and hundreds of up-to-date UE projects, most of which are still very relevant despite the major workflow shifts introduced with UE5.

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Ghislain Girardot @ghislaingir.bsky.social · 21/02/2026

Once again, thank you all so much for the love and support over the past few years. It genuinely reshaped my life 🥰

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Ghislain Girardot @ghislaingir.bsky.social · 21/02/2026

As many of you already know, I’ll be starting a new job on Monday — and that’ll be it for me 🥲 No new content for the foreseeable future.

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Ghislain Girardot @ghislaingir.bsky.social · 21/02/2026

This was long overdue and took wayyyyy too long to produce, but here it is. There are still a few knowledge gaps I was hoping to fill, but I ran out of time. 📺 Watch here: www.youtube.com/watch?v=NxIa...

youtube.com

Understanding C++ Compute Shader Dispatch and RDG in Unreal Engine

YouTube video by Ghislain Girardot

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Ghislain Girardot @ghislaingir.bsky.social · 21/02/2026

🥳 That’s it — my new and final video is live on YouTube! In this 2h15 deep dive, I try to summarize everything I’ve learned over the past two months while diving head-first into C++ compute shader dispatch in UE and RDG.

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Ghislain Girardot @ghislaingir.bsky.social · 13/01/2026

Thanks, that's handy. I knew alignment was a big topic haha but I never faced an actual issue because of it until now. I'll have to learn how to make better use of VS debug tools/RenderDoc. Could by handy...

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Ghislain Girardot @ghislaingir.bsky.social · 13/01/2026

Thanks. I'll have to see what Visual Studio offers for debugging structs :) I'll have to take a look at RenderDoc as well hehe

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Ghislain Girardot @ghislaingir.bsky.social · 13/01/2026

Roger that. But there's a broader understanding to have here I suppose. Using three float2 would be equally troublesome here, I think 🤔 Struct would still be padded to be 16bits aligned.

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Ghislain Girardot @ghislaingir.bsky.social · 13/01/2026

I'm a bit puzzled. Anyone care to explain what's going on like I'm a 5years old? 🥲What are the best practices to avoid getting owned again in the future? ty :d

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Ghislain Girardot @ghislaingir.bsky.social · 13/01/2026

At first I tried to add a float pad_ after float3 Location; and float3 Extent; in the HLSL struct but this didn't work. I suspect that's not where the compiler is adding padding to the CPP struct? Adding padding to both structs did work.

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Ghislain Girardot @ghislaingir.bsky.social · 13/01/2026

FVector3f says its 12bytes/4bytes aligned, FVector4f says its 16/16. I expected the struct size to be 40bytes but it's 48. I suppose the use of a FVector4f forces the whole struct to be 16bytes aligned?

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Ghislain Girardot @ghislaingir.bsky.social · 13/01/2026

oof, I got owned so hard. First time trying to use a struct in a compute shader. Things did not go as planned... After an entire day of debugging, structs could be the only culprit. This causes alignment issues. Using float4/FVector4f fixes it

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Reposted by Ghislain Girardot

Jorrit Rouwe @jrouwe.bsky.social · 10/01/2026

A sneak peak of what I've been working on: A strand based hair system for Jolt Physics (WIP): youtu.be/Rl19G0c003o

youtu.be

A strand based hair simulation running on GPU

YouTube video by Jorrit Rouwe

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Ghislain Girardot @ghislaingir.bsky.social · 02/01/2026

Anyway, I hope you all had great holidays 🥰 Happy new year!! Cheers.

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Ghislain Girardot @ghislaingir.bsky.social · 02/01/2026

It feels like a nice way to end my UE content creator journey. I kinda started with water, so I'll end with water I guess =) I'm hoping to do more stuff with interactive foliage before that though

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Ghislain Girardot @ghislaingir.bsky.social · 02/01/2026

This helped immensely: github.com/2Retr0/Godot... This as well: github.com/tigershan113... And that one, ofc: dev.epicgames.com/community/le...

github.com

GitHub - tigershan1130/UE4_FFT_Ocean: FFT Ocean 4.26

FFT Ocean 4.26. Contribute to tigershan1130/UE4_FFT_Ocean development by creating an account on GitHub.

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Ghislain Girardot @ghislaingir.bsky.social · 02/01/2026

Next: - Get a better understanding of the many existing FFT GPU/CPU algos - Cascades - Foam & velocity - Splashes - Copy UE's water quad tree - GPU Readback - Get more comfortable with UE's RHI - Clean code - Try using UE's FFTGPU - Make a video about it before end of February :|

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Ghislain Girardot @ghislaingir.bsky.social · 02/01/2026

Holidays side project. I'm trying to join the FFT ocean gang😅 I'm now at least somewhat more comfortable with various GPU programming paradigms and UE's RHI & CPP compute shader dispatchs, but I've so many questions still😅

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Ghislain Girardot @ghislaingir.bsky.social · 21/12/2025

Files are available as a Tier 3 reward on my Patreon: www.patreon.com/c/GhislainGir Thanks for the support <3 Cheers

patreon.com

creating educational UE projects and a video game!

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Ghislain Girardot @ghislaingir.bsky.social · 21/12/2025

New video on my YT! 🥳 A 55-minute deep dive into God of War's dual-depth foliage interaction technique. ⬇️🧵

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Ghislain Girardot @ghislaingir.bsky.social · 17/12/2025

Damn, that's fantastic work! Thanks for sharing. Always a treat to see WIPs of complex systems like this :)

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Ghislain Girardot @ghislaingir.bsky.social · 17/12/2025

No worries about the wall of text :D sry for the late reply. I'd be curious to know how they did it for PoP as well. It appears UE has all the built-in tools to rewind anims and what not for debugging purposes, so I'm assuming it can be recycled for gameplay as well. I'd have to look at their method

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Ghislain Girardot @ghislaingir.bsky.social · 17/12/2025

Almost done with this. Hoping to be done with the breakdown video before holidays :)

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Ghislain Girardot @ghislaingir.bsky.social · 14/12/2025

Files are available as a Tier 3 reward on my Patreon: patreon.com/c/GhislainGir Thanks for the on-going support🥰Next video will be about GoW dual depth foliage interaction technique! And then more VFX/shader stuff :) Cheers!

patreon.com

creating educational UE projects and a video game!

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Ghislain Girardot @ghislaingir.bsky.social · 14/12/2025

🥳 New video up on my YT! I’m showing how I hack around the Character Movement Component in Unreal Engine to build custom movement modes—all in Blueprints. It’s a bit old school, but it still works like a charm for simple games! 😊

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Ghislain Girardot @ghislaingir.bsky.social · 13/12/2025

It's all about managing a struct of data, that I agree :D State machine wise, it's complicated, at least in my head. Say anim A blends to anim B based on condition at X time, I don't quite see how you rewind from B > blend > A without building a separate state machine with reversed conditions etc.

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Ghislain Girardot @ghislaingir.bsky.social · 13/12/2025

random thought of the day: Prince of Persia's SoT time rewind thingy in UE. How. Character animation specifically. 3, 2, 1, go🙃

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Ghislain Girardot @ghislaingir.bsky.social · 08/12/2025

When the debug tools are almost as cool as the tool itself :) Here I'm debugging a slice of the dual depth map. Red is held height, green is faded height. Delta between the two + fade ratio gives the time, which can be used to play a cheap spring animation for the grass

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Ghislain Girardot @ghislaingir.bsky.social · 08/12/2025

2019 God of War's Dual Depth implementation. I still have a few issues to solve 🤔 CPU Performance is 💩because Niagara's RigidMeshCollision interface lack a much needed rasterizing function, so I had to re-implement it from scratch in BPs for this proof of concept😅

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Ghislain Girardot @ghislaingir.bsky.social · 03/12/2025

Really glad I could help. Thanks a lot!

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