Renzatic on 6/9/2019 at 01:02
SWEEOOOT, YAKCOOP! CONGRATS ON THE RELOOSE!
Starker on 6/9/2019 at 01:36
Congrats!
zombe on 14/9/2019 at 08:09
Is it just me or is the image is broken?
PBR is a fairly nebulous concept. Not sure what is actually meant here.
Noticed something weird from the linked forum: "there are issues since the game was originally designed for phong based lighting". ???. Was it really limited to perfect reflection angles? Seems somewhat plausible, but not sure (when i faced the problem with my own stuff and was not willing to add another material channel for it then i combined light emission, reflectivity and "reflection cone" all into one channel - x_x not stellar, but pretty good. I would have loved Doom3 case where i would only need two of thous and it surely already encodes one of them anyway - so, why not have both combined?). If it did not even have reflectivity (bloody hard to believe) ... then wow, time flies i guess.
Iirc. doom3 was the earliest attempts at PBR (side effect of unified lighting and shadowing) with limited material channels / texture memory / stencil shadows (with limited light range and overlap to get overdraw/shadow geometry to sane levels) and complete lack of any ambient approximation. The linked video in the forum post seems to suggest that it is possible to mess up the material channels even more (at shader side presumably). The "fixed" version looks like phong on normal mapped surface to me. Wha... ?
Anyway. Interesting to see doom3 community alive and kicking (forum seems quite active).
Renzatic on 14/9/2019 at 09:19
Quote:
PBR is a fairly nebulous concept. Not sure what is actually meant here.
When anyone mentions PBR, they're more often than not talking about a specific set of textures, coupled with a specific shading model they're meant to be plugged into, all producing predictable results no matter what engine or rendering program you use. Because of it, you can expect a roughness texture to look about the same in Unity as it does UE4, or in Arnold as it does Cycles.
Don't think of it as a concept, as in lower cased physically based rendering. Instead, think of it as a standard, called upper cased Physically Based Rendering. If you want a more specific name to tag to it, call it Principled BRDF.
zombe on 15/9/2019 at 09:44
Erm. Not what PBR means in general (*), but what is being meant HERE. Might be, indeed, quite possible that some common solution is being meant here - but what was that solution supposed to do here i wonder? I have no clue.
Check the video linked in the linked thread: (
https://www.youtube.com/watch?v=0uyGz2CWoP8)
New PBR Lighting: looks like pure normal mapped phong with constant and extragrated reflectivity.
Old Phong Lighting: looks at least sane and not noticeably phong like.
The video seems to strongly contradict itself. So, what is the meaning of PBR here? Just that some common PBR shader code was badly injected into it?
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*) IMHO. PBR does not really mean anything besides signalling the intent of getting more perceptionaly accurate results using physics as its base / inspiration. Since the world we live in is physically consistent between all the observers then solutions inevitably will converge to common and often "standardized" solutions / options. That said, there is no one solution to rule them all and never will be - what is perfect for one context is useless for the other (ie. offline/online rendering, various GPU related budgets and most importantly - the range of material parameters and level of real world approximation actually needed). Hence why i called it nebulous. Without context it is pretty much meaningless (edge case ex: PBR of atmospheric/highly transparent effects vs completely opaque surfaces have essentially no overlap at all).
Sulphur on 15/9/2019 at 11:32
Hrm. Given that when people talk PBR these days it's generally opaque materials roughness/reflectivity, I fail to see the point of a PBR shader in an engine that doesn't do screenspace reflections. You could say it unifies the materials in the game (did idtech 4 really differentiate materials?), but clearly it fails here when human skin looks like cellophane. The forum post says they're taking the red channel from the specular map as roughness input, which is a decent kludge I suppose if you just want a proof of concept of something that blows out specular highlights.
Judith on 15/9/2019 at 16:14
Never underestimate the power of TTLG to weird me out... Although I thought this was mostly exclusive to ThiefGen psych ward. Renz gets it, the rest is some geek out wankery and facepalm material.
Nobody cares about your personal definition of PBR, Disney-based BRDF is an industry standard nowadays, and that's what's used here. Of course it looks wrong in the video, it uses non-PBR diffuse maps and RGB speculars. That's why everything looks wet. You just need to have enough brain cells to download a random metallic-roughness PBR textures from some free site, plug it into UE 4 and D3 with new shader, and compare the results. If you have Substance Alchemist, the material will look the same there, in UE4 and in D3 shader.
This is an early work in progress, so there are some errors. The guy who works on it is an ex idtech 4, 5, 6 programmer, working on engine features for e.g. Rage and The Evil Within. He plans to add things like lightmaps, reflection probes, volumetric lighting, postprocess bloom etc. So eventually it will become a whole open source package for vanilla Doom3 engine, so then people using different engine forks (like TDM) will be able to dig into his code and make proper adaptations.
Sulphur on 15/9/2019 at 17:17
Well, at least someone gets that ThiefGen is a psych ward. Though I'd still stand by my initial claim of it being a petting zoo.
Anyway, what you're saying is essentially that the dude's planning on retooling the engine to support the entire gamut of current-day PBR techniques for Doom 3? Which I guess makes more sense than just adding BRDF and asspulling roughness data from existing assets. From the forum thread you linked, it seemed very much like a proof of concept that was done just 'cause.
Renzatic on 15/9/2019 at 17:55
Quote Posted by Sulphur
The forum post says they're taking the red channel from the specular map as roughness input, which is a decent kludge I suppose if you just want a proof of concept of something that blows out specular highlights.
If I had to take a guess why everything looks so shiny, I'd say it's because oldschool speculars like what Doom 3 uses consider black to be matte, and white to be shiny, which is inverted in roughness textures, where black is smooth and reflective, while white is rough.
Plugging PBR shading directly into Doom 3 without tweaking any of the currently existing textures would give you...well, about what we're seeing here.