Nanite Tessellation, aka Nanite Dynamic Tessellation, aka Nanite Dynamic Displacement was the adjacent awesome characteristic I worked connected aft Nanite itself. Initial prototypes started backmost successful 2020, only months aft showing Nanite publically for the first time. UE5 still hadn’t moreover been released to customers yet. After a mates years of shipping Nanite successful things and past a mates of years much of development, Nanite Tessellation yet shipped successful UE 5.4 successful 2024. I started this constitute up soon aft but it has taken acold longer to complete than I ever expected. Needless to say, publishing each this has been a agelong clip coming. It will travel successful a bid of posts starting pinch this one.
List of posts:
- Intro
- Possible approaches
- How to tessellate
- Nanite + Reyes
- Variable sized work
- Vertex deduplication / Post toggle shape cache (coming soon)
- VisBuffer / Deferred materials
- Wrapping up
What is Nanite Tessellation?
A strategy for dynamically tessellating meshes and displacing them. The displacement comes from a shader graph, authored successful UE’s worldly editor. This tessellation is successful summation to what Nanite already provides.
Tessellation demoed astatine GDC successful Marvel 1943: Rise of Hydra
Patches
Diced triangles
Final pixels
Why?
Why is geometry amplification needed erstwhile we person Nanite? I’ve based on successful the past that amplification approaches to the virtualized geometry problem were not bully enough, truthful why would I commencement moving connected it now? Have I changed my mind? No. My statement was that amplification approaches are not a wide intent solution to the virtualized geometry problem. They do not lick each cases. They can’t alteration the genus of a surface. A simplification attack would ever beryllium needed. If you person that it could besides lick amplification successful a way. A mesh could ever beryllium synthesized, subdivided, tessellated, and/or displaced offline. Then simplification tin trim it down. This ignores the information retention implications but it does show that it is the much wide intent solution to that problem.
So we person that now. It’s called Nanite and is beautiful cool. It was the correct point to activity connected first. But conscionable because this solution is wide intent capable that it tin beryllium utilized for these different cases does not mean it is perfect for them. Storing afloat topology of an irregular mesh covers each cases but is expensive. Storing each position connected the aboveground arsenic a afloat 3d constituent pinch a complete group of attributes is expensive. We do our champion to compress that information but thing thumps not having that information astatine all.
Compression
Scalar displacement fields, whether they are creator authored maps aliases captured done projection of a elaborate aboveground to a simpler one, are overmuch little data. 1 worth compared to 5+. Compression of regular 2D data, i.e. images, successful narration to quality cognition is vastly much researched and good understood.
Comparison of disk size for precocious poly vs debased poly pinch normal and displacement maps
Even amended information compression than that are procedural texturing approaches. What do I mean by procedural texturing? I don’t conscionable mean mathematical functions for illustration Perlin noise. I mightiness beryllium pushing the meaning a spot but moreover elemental texture tiling successful a measurement is simply a shape of procedural texturing. But surely erstwhile shaders are progressive wherever aggregate textures are mixed and modified we are successful the realm of procedural. The simplest shape of this is item texturing. A overmuch higher wave awesome tin beryllium represented than stored explicitly. Viewed statically for illustration this, the compression ratio tin beryllium acold higher than is achievable done immoderate different means.
Authoring
But beyond information compression, procedural contented procreation tin beryllium an incredibly effective clip saver for an artist. It besides tin beryllium reusable, dynamic, and animatable. By reusable I mean that a guidelines worldly type, for illustration snow, tin beryllium authored erstwhile and applied to galore surfaces. By move I mean the aforesaid plus tin accumulate snowfall complete clip by changing the shader parameters, each the measurement to afloat animation for illustration a moving lava section flow.
Displacement maps are highly communal successful movie and the superior logic for their usage is not information compression. A bully spot of it is tooling and while I could opportunity that should beryllium improved and is personification else’s work to support up pinch Nanite’s capabilities, the truth of the matter is I can’t threat my fingers and alteration each the DCCs. Even if each exertion were each optimized to amended activity pinch precocious poly meshes location is ever thing inherently simpler pinch 2d textures, and displacement maps are nary different.
Displacement’s usage successful movie besides helps animation. For a characteristic the guidelines cage tin beryllium rigged and deformed. The deformed cage tin past beryllium smoothly subdivided and displaced to get the last detail. This simplifies the rigger’s and animator’s concerns and separates them to an grade from the sculptor who mightiness carve retired individual dragon scales.
The past usage lawsuit is circumstantial to games. Scalability is an important information for Fortnite arsenic good arsenic different games that still request to support little extremity platforms that aren’t powerful capable to tally the Nanite pipeline. We tin easy make debased poly fallback meshes done the aforesaid mesh simplification algorithm that Nanite uses, but what is good for the region isn’t needfully bully capable for up close. The creation of debased poly modelling is often a matter of abstraction of style and artists are overmuch much picky astir the results. They will besides move item betwixt domains, from mesh to texture, that requires engagement of different assets that is difficult aliases intolerable to automatically do reliably. For these reasons, erstwhile a ample scalability scope is required, for illustration pinch Fortnite, our creation teams person been much comfortable authoring for debased aliases mid successful the scalability scope and amplifying up alternatively than authoring for precocious and simplifying down.
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