Unity's official blog announces product, pricing, acquisition, and technical updates for the game engine company.
HN links it for the pricing and runtime fee announcements, which prompted talk of switching to Godot, and for technical posts like the deltaTime fix.
Unity also bought SpeedTree, which did the vegetation in Avatar 1 (and in many video games). They bought Weta Digital in 2021 (https://blog.unity.com/news/welcome-weta-digital).
Blender has a FLIP plug-in I believe. The water in UE isn't great, but the "fluid flux" plug-in is surprisingly impressive for real-time water https://www.unrealengine.com/marketplace/en-US/product/fluid-flux
Computational Fluid Dynamics is a tricky area. The science (Fluid Dynamics) was worked out over 100 years ago, with the Navier-Stokes equations (3D partial differential equations). The engineering (the Computational part) is a whole bunch of complex and clever tricks, to overcome surprising problems like instability and dissipation, and often for some particular engineering trade-off (rather than being universally true).
Avatar 2 seems to use an underlying FLIP simulation for the water (which uses a (eularian) grid for pressure, and particles for movement), with cinematic tricks on top: foam, bubbles, and smaller (lagrangian) waves superimposed.
The Fluid Flux plug-in uses a simplified version of the Navier-Stokes equations, which represents the upward direction as an average - so it's 2D internally but looks 3D. It also just calculates once, instead of iterating. Both make it much faster. It uses this paper, which has several other tricks: https://matthias-research.github.io/pages/publications/hfFluid.pdf
The blog post: https://blog.unity.com/news/plan-pricing-and-packaging-updates
You are likely already paying a recurring cost to Unity, as per https://unity.com/pricing: Excluding the free Student & Personal tiers, the starting list price is $2,040 per year per user (for Unity Pro), going up to $4,950 per year per user for the top tier (Unity Industry).
So, this is a new charge, which becomes active when the following conditions are met for a particular game:
• # of installs, over the life of the game, passes 200k (Personal) or 1MM (Pro/Enterprise).
• Revenue, over the last 12 months, passes $200k (Personal) or 1MM (Pro/Enterprise).
Once both of those thresholds have been met, then you get charged a flat fee per install over the threshold. So, if you meet the Revenue amount, and you've had 200k/1MM installs, your next install requires you to pay a fee to Unity.
This is all covered in the table at https://unity.com/sites/default/files/2023-09/NewFeeTable.png
For games that are not being distributed through a channel (Steam, GoG, console/app store, etc.), this is going to be really annoying to track and report on. This is also going to be annoying for games that are distributed through multiple channels. Unity's probably going to get into the auditing game at some point; à la Microsoft, Oracle, etc.
Unity actually started doing this while I was working there[0], and then eventually axed it[1] as part of a broader shift towards low quality high revenue mobile development (acquiring ironSource, for example). This shift was highly demoralising for the entire organisation, as it included laying off huge swathes of creative staff from Gigaya development (and other teams) and hiring in areas of monetisation (read: advertising and tracking).
Unity is no longer a games engine company, it is an ad company. It is taking surprisingly long for people to see it this way.
It was really sad to me, because (possibly naively) I saw joining Unity as a potential opportunity to pivot more closely to game engine programming (from web), but that was an uphill battle given that the resource allocation was massively in the opposite direction.
0: https://blog.unity.com/games/introducing-unitys-latest-sample-game-gigaya
1: https://80.lv/articles/unity-stopped-the-production-of-its-sample-game-gigaya
There is some kind of continuing relationship between the two: Weta FX will keep contributing assets to Weta Digital's (i.e. Unity's) asset library. Maybe that's in exchange for being able to continue to use the software? I haven't seen the deal spelled out anywhere.
From the Unity blog post [1]: "Another exciting element of this acquisition is the asset library we’ll inherit from Weta Digital, which includes urban and natural environments, flora and fauna, humans, man-made objects, materials, textures, and more. The WetaFX team will continue their industry-leading VFX work for major film and TV productions and feed into this asset library for years to come."
[1] https://blog.unity.com/news/welcome-weta-digital
Usually when this pops up I drop in to tell people not to waste their time with it, but, people are relentlessly drawn to free content, no matter how questionable it is.
Instead, today I'll link to different free content that is actually useful advice by people who know what they're talking about: https://blog.unity.com/games/level-up-your-code-with-game-programming-patterns
...also, checkout the link at the bottom to their forum where there's some (reasonably) thoughtful commentary on it by folk who've been down that rabbit hole themselves; including why "Game Programming Patterns" misses the boat in at least some respects.
Only games that meet the following thresholds qualify for the Unity Runtime Fee:
Unity Personal and Unity Plus: Those that have made $200,000 USD or more in the last 12 months AND have at least 200,000 lifetime game installs.
Unity Pro and Unity Enterprise: Those that have made $1,000,000 USD or more in the last 12 months AND have at least 1,000,000 lifetime game installs.^
So, if you have the Pro or Enterprise that most studios have, they should have more than 1 million Revenue in the last year AND have more than 1 million game installs.
https://blog.unity.com/news/plan-pricing-and-packaging-updates