In all honesty, I see no huge practical issues with Compatibility lighting at this point. People seem to be looking very strongly at the negatives and not at the positives (like that supposed 5% speedup that will come from the change).
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Are you using textures on those rocks? The specular highlight depends on what the material of the part/mesh/union operation is. Try switching out the material for a different one, like Concrete, something like that.
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Sacrificing quality for a 5% speedup isnât a good idea, especially with a core part of Roblox ( the lighting )
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This is entirely true. Just felt like bringing a more positive outlook onto the situation; the popular opinion still seems against compatibility although I have no personal preference between the two. Honestly, with shadowcast, I donât think Iâll ever use either.
Thereâs a couple misconceptions Iâd like to address in this thread; these updates donât have much to do with catering to a specific audience, and while they are a bit more aggressive wrt timing compared to our usual practice, thereâs a reason for that. Stay tuned for a long reply to follow⌠(in an hour or so)
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So let me start by saying that we actually read things that you post 
Feedback is welcome, even if itâs negative (but please be polite and respectful of the work weâve done), but keep in mind that we may disagree with some of it and as a result not act on it.
Why did we introduce Compatibility if itâs so obviously different than Legacy and looks worse? Well, looking better was never the point of Compatbility. Let me walk you through the decisions weâve made and explain why we made them.
Roblox in the old days had very primitive lighting. Iâm sure some of you remember the days where there was just the sun with no shadows - I surely do because my first project was to build a dynamic lighting system. (stencil shadows donât count, ShadowMode: All was not available in-game as an official feature) The foundation of the lighting system is a rendering equation, and the one we used worked like this: it took the color of the part, took the lighting value computed using directional light, and multiplied the RGB values together. If lighting was 1 (which you could easily get by maxing out Ambient or Brightness), you got the exact same color you used - plain and simple.
Thing is, real world doesnât work like this. When we built the original Future Is Bright prototype, we very quickly realized that to get where we need to be in the future, which is âawesome visualsâ, we need to use a more realistic model of the real world lighting equation. This needs two foundational components:
- High Dynamic Range. This means intermediate values arenât clamped to 1, which is why you can get high contrast between lit and shadowed areas.
- Linear space lighting. This means all equations must be performed in a different space compared to sRGB that youâre used to seeing in color pickers et al - in this space, values correspond to amount of physically emitted light in a linear fashion. I donât want to go in too much detail about âwhyâ here, but thereâs a lot of good material on the web, in particular Linear-Space Lighting (i.e. Gamma) â Filmic Worlds (take a look at the image in the beginning - this shows that in the sRGB space youâre all used to, the color âin betweenâ 255 and 0 perceptually is not 128 - itâs 192! 192 maps to 0.5 in linear space, making the math correct.
Once you have to have high dynamic range, you also have to have a tone mapper - it remaps higher-than-1 values to 0âŚ1 range that can be displayed on conventional display panels. The process of making a tonemapper is on the intersection between art & science, but we had to make one - itâs a critical piece of the system.
And this is almost all there is to it about Voxel. We need HDR. We need linear-space lighting. We need a tone-mapper. Once you accept the fact that you need to model real-world optics, you just canât get away from these things. The only other component of Voxel is anisotropic occupancy - itâs an extension to our voxel grid that makes it so that thin parts donât let light through. (the current implementation is limited in that it still lets light leak through corners which is something we want to address in the future)
This is also where concerns about âvibrant colorsâ come in. Take a look at this picture from Unityâs docs:
Do colors in gamma space look more vibrant at Intensity 1? Uh, I guess. But thatâs not how the real world works. And higher intensity values result in really blown out images, which is bad when you start talking about HDR and modeling real-world lighting values.
This is why we made Voxel. ShadowMap is based on the exact same math. This is the foundation for our future improvements that add light shadows and more precise local lights as well (aka FIB v17).
We strongly believe this is how content should be built. We strongly believe content looks better within this new mathematical formulation. It seems like the majority of the community agrees - you can get much better quality with the new system.
Voxel isnât perfect. Thereâs some technical limitations wrt shadow fidelity, light leaking; thereâs also issues with specular highlights that fundamentally stem from the fact that when youâre modeling real world, but every single surface with a custom texture behaves like painted plastic, things donât look so good. We will be addressing these with future updates but even given these limitations, Voxel is a superior system.
Which brings us to the question of existing content. (and I need a break)
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Ok, so the real difference in Voxel is that itâs a different mathematical foundation. Rendering pipelines are like 50% math; by changing the fundamental assumptions about the color space you work in, you have to redo a lot of the work. We had to very substantially change the water shading for example because the way things were done before were effectively hacked together up until they look right; itâs harder to do this when the underlying foundation is sane, you have to be more rigorous about your derivations.
This mathematical foundation is crucial for all followup work that we do - so all future development will happen in this framework. However, when you change the mathematical model, but keep the numbers that are being fed into it (which in our case is the content that you have made - part colors, lighting settings, textures) - you get a different result. Since content is often tuned to the current behavior without regards to whether the values are physically correct, naturally just flipping the switch doesnât work. This is why you need to tweak a lot of settings to make your levels look reasonable when switching to Voxel.
We need to have the existing content work. How do we do that? The obvious solution is to keep Legacy forever. Thereâs two big issues with that.
One, itâs a constant tax on maintenance on existing system and development of new features. This isnât exclusive to this project - I mean, youâve heard it all before, this is why we removed old terrain, this is why we removed old physics solver. For example, we had to redo the water shader for the new model - the old one is still around to support legacy. We had to redo postprocessing pipeline - the old one is still around to support legacy. Whenever we implement new materials - forcefield, for example - the development time increases because both need to work. Whenever we change existing features, both need to work. But they are so different that it takes time to do that.
Two, itâs a tax on performance as well. Because of teleports and some other constraints, we need to be able to switch between these often; thereâs some restrictions that this imposes on some systems that I wonât go into - suffice it to say that the option that we had to choose to not go completely crazy wrt maintenance is to emulate parts of the old pipeline by doing extra work in our shaders.
When we originally released Phase 1, we actually didnât duplicate some things like the post-processing pipeline - large parts of it were shared between the two systems, and could be configured to work in either mode. This code runs on your GPU and has to process millions of pixels/vertices - the price for even small things is very high. This is part of why phase 1 took more time to ship on all platforms than we thought - we had to go back and completely fork the post-processing pipeline to mitigate some of the performance loss. This is because, when you emulate both systems on the GPU, your cost isnât equal to the cost of the currently selected system, and itâs not even max(system1, system2), itâs somewhere between max(system1, system2) * overhead and system1+system2 depending on the case.
After we fixed that by duplicating the entire postfx stack, we still emulated both systems within the main rendering passes - these are much harder wrt maintenance for us to duplicate. This is where the resulting ~5% performance overhead comes from (itâs actually more significant on lower-end devices where it hurts the most).
So itâs a big issue that we have both systems - not because we have two of them, but because theyâre so different.
A good counter-example is Voxel vs ShadowMap. Youâd think that itâs hard to maintain both, but we need Voxel on lower-end platforms that donât support ShadowMap and low quality levels for players with weak hardware, so we donât lose much by supporting Voxel as a dedicated mode. The only issue is that we ended up with two shadow systems (Humanoid shadows in Voxel mode and full scene shadows in ShadowMap mode), but Iâm hoping we will find a good way to merge them, in effect using ShadowMap only on your player character in Voxel mode in the future.
Keeping both systems is problematic. Historically the way weâve dealt with this is wait for developers to migrate (thank you to so many of you who have migrated their games to Voxel!), announce the complete switchover some time in advance, switch and assume that most content works okay and the content that doesnât can be migrated at some point later. This wasnât appropriate in this case.
edit: Iâm blocked by 3 consecutive replies rule, so Iâm waiting for somebody else to reply to this thread to post the final part of this really long update.
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Great update, Roblox! I look forward to what people will create with this new lighting system!!
There you go, @zeuxcg.
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The reason why system migration takes a while in Roblox is because usually, when you switch from one system to another, youâre going to have behavior differences; no matter how good or bad they are, they can break games. The games become unplayable. This is a problem. This usually doesnât happen for rendering features - one day outlines will disappear from Roblox (sorry) but itâs hard to imagine many games that would become unplayable as a result. Lighting is different.
Thereâs three common issues weâve seen when just switching to Voxel:
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Areas that used many lights with extremely high brightness were just white. Old system didnât support HDR so it clamped the impact of all lights to 1. New system supports HDR so it faithfully reproduces the incredibly bright color which then gets transfered to the screen, but the tonemapper canât figure out how to expose this (have you ever tried to take a photo of a large dark building against bright sky? Youâll know what Iâm talking about - sky will turn white because the image is overexposed for the sky, or building will turn black because the image is underexposed for the building). This breaks gameplay! You canât see things anymore.
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Areas that used buildings with thin walls without any lights inside were just black if Ambient was 0. Old system didnât support thin walls. If the walls were thicker, the place creator would put lights inside the building, but the walls were thin so they didnât feel they have to. This breaks gameplay! You canât see things anymore.
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Games were generally darker than expected. This is because of the math difference between linear space lighting and sRGB lighting. This is why we recommend increasing Brightness a bit during migration. This rarely breaks gameplay, but is inconvenient.
Issues 1 and 2 were relatively common. This means we couldnât treat this as a rendering feature for the purpose of migration since it effectively breaks behavior by rendering (see what I did there?) the game unplayable.
However, the performance and mainteinance overhead is really important. We want to release more updates to rendering that have a bit more rendering cost, and yet we canât fix the 5+% cost of having to keep Legacy afloat. We want to release more rendering features and yet for many we need to do extra work to support Legacy. (in fact, easily half of the bugs in the initial ShadowMap release happened because we still have Legacy!)
This is what Compatibility solves. It fully solves problem 1 and 2, and mostly solves problem 3. Problems 1 and 2 are solved by clamping the output of the lighting system to 1 (which is almost free) and disabling anisotropic occupancy (which is free); problem 3 is solved by adjusting the input parameters - light color, intensity, bloom strength, tonemap parameters - to try to match Legacy better (which is free).
Hereâs what we get as a result.
Existing places donât break when transitioning from Legacy to Compatibility. They donât look the same - mathematical models are still different! - and they donât look better - we canât retune your content for you! - but we make sure that if you could play the game before, you still can, by eliminating the gameplay-breaking parts of the update.
We donât have to pay the performance penalty. All existing places get a slight boost in performance for low-end systems.
We almost donât have to pay the maintenance penalty. Thereâs a very thin layer that adjusts input parameters, and thatâs basically it. Not quite zero cost but really close.
The expectation is that developers that want their games to look great will learn to work with the new system, and if they need to exercise artistic control to push their game to have more vibrant colors etc., the hope is that between lighting controls and color correction effect thereâs a fair amount of options to play with to reach good results.
The expectation is that there will be developers who donât have the time or desire to update their games, and these games will look a bit differently - maybe worse than they looked before - but will still be perfectly playable, so players will still enjoy them. This is the compromise - we canât guarantee the same look, but we can try to make sure you donât lose players.
As you can probably tell, Future Is Bright is a really ambitious project. The way to ship ambitious projects is to do it in small chunks (which is why weâre splitting it into so many phases) and to try to execute them quickly - as much as weâre able to. We really want to give you even more cool features to play with but the performance issues (that we have to be very serious about when making these changes) and the maintenance issues hamper our progress. This was a big concern with Legacy - we could never replace Legacy with Voxel due to aforementioned gameplay breaking issues. But with Compatibility solution, it seems like the real issue is that some developers are attached to the Legacy look and arenât able to reach the exact same visuals with Voxel.
We canât wait forever for Voxel and future technologies to become âperfectâ. And itâs not clear that we can make everybody happy no matter how many updates to Voxel we do. Which is why we decided that the state of Compatibility is good enough for players to still enjoy your games, and to sunset Legacy to make sure that its presence doesnât impact current and future work.
Thank you for reading.
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Is Shadowmap still only available to studio? And if I publish something that is in shadowmap will the game be automatically be converted to voxel?
If nothing goes wrong, ShadowMap should be rolling out to the client today or tomorrow. (pls correct me if im wrong @zeuxcg).
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Shadowmap is still only a studio thing, and your game will be converted automatically to compatibility if published with Shadowmap enabled.
Update: Forced compatibility is postponed due to the bug in UI system. Will post new date here soon.
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Good to know.
i personally allwys preferred legacy lighting over everything else
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Shadow Mapping is far superior to legacy.
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Could you explain why you prefer legacy over the other Lighting.Technology options?
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I mentioned this in another thread, but Iâll post it here too.
For anyone who wants Robloxâs legacy tone-mapping while using shadow maps, I found a ColorCorrectionEffect configuration that gets it pretty much on-point.
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For day time itâs spot on, but night time it becomes awfully hazy.
Itâs not quite legacy, but removing some of the negative Contrast is a big help.
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I think this can be fixed by adjusting the contrast based on the Y-value of the sunâs direction. Iâll look into it more when I get the chance.
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