With Nanite, Masked Materials are much more expensive.
I would like to have a material be opacity masked closeup, but at a certain distance just become opaque.
Traditionally, this would be easily achievable, by just assigning a different Material for a LOD.
With Nanite, this option no longer exists.
The context is wanting to have a much cheaper material in the distance. Especially nanite hugely benefits from opaque materials. So being able to have an opaque blend mode in the distance, where the difference can’t be perceived, would be a big performance win.
So, in a traditional non-nanite LOD Pipeline, x-trees, sprites or imposters would indeed be used.
However, for nanite, imposters would not be necessary. It would be possible to have a regular mesh, that approaches the shape and silhouette of the mesh very closely. That is thanks to nanite’s triangle per pixel paradigm.
It would make it possible, to disable masked materials completely. Without any difference in visuals. Or almost none. But the performance savings would be very high.
You could use a blueprint that swaps meshes at a certain distance, but RecourseDesign is right, when Nanite meshes are only a few pixels, they are swapped with impostors.
I found something definitive: (I didn’t realize they were quite that small though)
At very small scales, even low-genus objects run into visual changes caused by over-decimation. Nanite overcomes this by pre-rendering 12×12 pixel imposter images from 144 different view directions in advance and using the image that most closely aligns with the current view direction if the object’s on-screen bounding box is less than 12 pixels in size. That solution requires memory for the set of imposters and can result in popping, so the Nanite devs have expressed a desire for something better. It also doesn’t do much to help with grass, leaves, hair, screens, blinds, and other large objects made from the cumulative visual effect of many small pieces.
I was not aware, that nanite turns assets into imposters when they get smaller than 12x12 pixels.
However, that is not a solution at all for the problem.
If we assume fullHD, that would be equivalent to a screen size of 0.011.
If we assume 4k, that is a screensize of 0.0055.
But there is a lot of assets at screen sizes in the range of 0.2 to 0.011(or 0.055).
These assets would often benefit hugely from not being rendered with a masked blend mode.
Hence a way to switch out the material or the material blend mode, at a certain distance, would be extremely helpful for optimisation of open world levels. Especially those that feature lots of masked materials.
I had my benchmarking level open anyway so did some tests and you’re right - it can save a good amount of GPU time - but it does introduce a different type of internal lighting - you don’t notice the opaque branches of leaves, you notice the shading of everything is suddenly darker…
The link below is just a comparison slider between masked and opaque foliage:
Is there a CVAR to disable at least all masks on all materials in the scene ? So you can at least disable all those for testing purposes.
Sort of like a : r.TextureMasking.Disable 1 or something
Curious, but this would also benefit world position offset… i ahve powerlines that sway in the wind along with airconditioner fans that spin in the material. How could i set up an lod to disable world position offset for nanite meshes? It is quite expensive for nanite.
Nanite for me is important. I have materials that are layered that have a near 0 vertex shader cost… using vertex colro to blend edge wear and dirt build up via baked ao… and baked curvature…
Not to mention basically 0 draw calls since most things in my scene use that material…
Also i found the solution. (in unreal engine 5.3 there are options for lumen invalidation and world position offset disable distance per static mesh…
