summarize the text:  Hello and welcome! Today on this very relaxed edition of Digital Foundry Let's Play, we're playing a very special mod for Minecraft that adds some very special lighting to the game. And to play it, I'm joined by my friend and colleague John Lineman. Where you at, John? I am right here. I've come down from space to join you on this trek through this wonderful world that you've crafted, this fun house of ray tracing, if you will. But I think before we dive in, you should probably explain exactly what the heck this is that we're looking at. Yeah, this is a mod for Minecraft written by the author Sonic Ether that adds path traced global illumination into the game. that adds path traced global illumination into the game. And it's using the old Java version of Minecraft and I think the 1.212 version of it with the Optifine shaders or Optifine optimizations, basically to make it run a bit better and also allow for shader editing. And my goodness, it is quite fantastic looking indeed. But the reason why we're here to talk about is the whole kind of hubbub about ray tracing with the PlayStation 5 reveal. And this is a very interesting version of ray tracing indeed. And we're running on two very different rigs to show it off. John, what are you running on there? So as usual, I have the venerable i9-7900X paired with an RTX 2080 Ti and 32 gigs of memory, which is great for this version of Minecraft. And you're running something very different. Yes, I'm running on something that is technically, in most of our comparisons, a little bit more powerful than an Xbox One X. The GTX 1070 as the GPU with a Ryzen 1700X and 16 gigabytes of RAM at 3200 megahertz. But you may be looking at my screen wondering, gosh, that looks a bit chunky, even from Minecraft standards. To get this running, I'm playing the game at 720p and locking it to 30 FPS with adaptive sync. Basically, this mod is very heavy, and it's even heavy on your rig, isn't it, John? Yeah, that's right. I'm running at 1080p with adaptive sync, but I'm hitting 60 FPS, but it is not 100% locked with the settings that we're using, though it is possible to adjust some things downward a little bit to improve it. But, you know, I think, Alex, that's enough talking out here. I think what you've constructed here is a shrine to path tracing and a series of rooms, each one more insane than the last to showcase exactly what the heck this does and why it's so important for real-time graphics rendering so um yeah let's go on in i mean before before we go in though why don't you come over here for a second even though your shadow or your name is glitching out if you look over here you can actually see shadow map casting on the wall there with your username. It's a neat touch. I absolutely adore that, actually. Diegetic stuff like this is so cool. But anyway. Let's go through the path of path tracing. The first room is very interesting. This reminds me of basically Half-Life 2 demos with that kind of specular sheen bounce lighting going everywhere. Well, this whole thing reminds me of the original Source presentation. The only thing we're missing here is Gabe Newell talking about, you know, welcome to Source 3. This time we have added path tracing. Oh my God. I can dream, right? But this is an interesting setup here because there is no direct lighting here at all. The area underneath here, which is lighting up the room that we're in, is only indirectly lit itself. So we're seeing two bounces of lighting here to even light this room up at all. And there's even shadows. And John's going to place some blocks here, blocking it all up. And you'll see the room go basically pitch black. Exactly. And, you know start to clear out the blocks you notice you can actually sort of see the shadows generated in real time yeah all this is happening in real time you see the specularity of the pink block reflecting off of here you know we'll clear this up but it gets more amazing here you know if you start breaking through over here let the sun in you see that yeah sort of like the light just like pours into the room you can you can see the specularity on the back wall this this huge cone of light coming right in there can even set that there and get a little bounce lighting on it it's uh the one thing that makes this kind of even work it's it's very heavy obviously um and it's not using the RT core on your rig. This is OpenGL, obviously, not DirectX 10 or not DirectX 12 or Vulkan. So it can't use the RT core for you. And it's a very specific version of ray tracing, actually. Well, I'm going to have to cheat to get back up. So, yeah, I mean, you know, we'll get into some of the details on how this works in just a second. But this showcases an interesting, more software-driven method for achieving these effects. Yeah. Although, as you can see, the requirements are still extraordinarily high. 30 FPS, 720p for me. Your rig is more powerful than the most powerful current generation console, Xbox One X. And yeah, let's go to the next room. Yeah, this is so Alex, what? Oh, I guess I shouldn't go down that hole. No, that's a scary hallway. So this room, I wanted to show off basically three things. There's kind of the differentiation in the materials on the ground that have different levels of reflectivity, so you can see more of the reflected light and different hues of it, basically, on the material itself. And also this kind of sky lighting above, which is affected both by this color of the sky, which is blue, you know, with a like a bit of white from those clouds. And also there's a tiny bit of bounce lighting here from basically the dirt and the tree giving it a green hue and it's this very glossy material that's not completely reflective and it honestly just looks like architectural rendering from here it looks this is fantastic looking it does i love this serene garden yeah but you know the block light structure of minecraft is actually key to uh its implementation here i think yeah it's uh talking with sonic ether the minecraft's ability to kind of or its limitation to have the entire world always be known as being made of blocks uh is what makes this so performant already as it is. Basically it has the conceit or assumption always that the blocks will just be either deleted or existing or not moving at all. So what keeps this so performant is that the fact that the blocks themselves cannot necessarily move and those are the only thing taking into account for the GI. Both the shadows from the blocks and the blocks themselves. So John, interestingly in the corner here, you can see how he has a reflection if he gets near the wall. That isn't from the ray tracing itself, rather you can see that when he goes off screen it disappears. Yup, exactly. It's a screen space calculation done for dynamic objects and I think transparencies as well too. So yeah it's a hybrid solution for this then and naturally the the fixed block shape of Minecraft worlds is perfect for a voxelized structure. It's perfect. Because it's you know it just fits like a glove and because these objects are non-moving and it's a binary on off you, present or deleted kind of situation. Exactly. That makes the calculations easier, which is very different from the sort of the modern, well, not the modern, but the other more robust solution used by games such as Battlefield V and Metro. Yeah, those games can have contributions into the ray, you know, contributions into the ray tracing from dynamic objects and skin dynamic objects as well, but they're obviously very expensive in their own right too. But let's go into the next room to talk about some more stuff as well. Yes, this room is exciting. I actually love this. This is one of my favorite rooms. Yeah, this one's my favorite. This looks so cool. Basically, what I want to show off here was kind of the effect of the lighting hitting different colors and bouncing them off directly into the room. And depending upon the material, you can see more of that diffuse and specular reflection itself. And this is actually something we probably mention often in the videos. And it's just a natural idea of light particles, photons sort of bouncing off a material and scattering the light against other materials nearby. I mean, this is how light functions in the real world. And many games have ways of sort of faking this effect currently. And it does exist. But this is generated entirely in real time. And you can see that kind of when I move in front of it, the shadow is obscuring the light causing the reflection to also be obscured as well too. Exactly. I mean sure. Go ahead. Oh yeah sorry and the interesting thing about this is we've seen kind of voxel based tracing demos in the past that use cones but this one is actually tracing with rays through this kind of blocky structure and it's a bit noisy mainly because i'm running at 720p and there's not that many rays and right there's also the problem that these are very low resolution textures i mean it is minecraft people so they kind of block out a bit more making them look a bit weird but still i think the the overall effect is is phenomenal and you know you see the light comes in through here. The sun enters through. It bounces up there. You turn around, you actually see the specular image of the blocks behind us. And this is a perfect example because, and it's something you're right. We don't really see this in typical games these days where we have these bright primary colors. No. So RGB, of course. bright primary colors no and it's uh so rgb of course uh and it's just you know it's perfect for demonstrating the benefits of proper bounce lighting it's why when you see the the more simulated faked methods in in actual shipping games it tends to be most visible on things like a marketplace with bright red umbrellas and the sunlight sort of bouncing off of that but you know again hey that's a little bird there but if we start placing blocks it gets a little interesting as well because this you actually see the sort of the colors become almost additive yeah the light bounces off the red then bounces off the pink and it sort of becomes a purplish uh a deeper hue and if i place like uh let's play some blue blocks in here as well you start to mix colors and everything you can see the mixing over here so weird looking uh very 80s kind of color schemes going on the back side of this is turned green almost uh uh the way this works is kind of interesting there's, in real time it's doing one bounce for both the fuse global illumination and the specular reflections. So that's the only mainly real time component. Then after that's done, it accumulates by a technique called surface caching, I believe, multiple bounces. So if I were to remove one of these walls right here, you can see that there's a bit of ghosting. That's because it's cleaned up over time with temporal AA, and because it takes about four frames for the lighting to completely generate perfectly almost. So the room will get lighter over time over more frames, over about four frames. Sorry to destroy your masterpiece, Alex. Oh, it's okay. It sort of demonstrates when we let the full light in here and the way that changes it really does feel somehow very natural like your eyes just adjust to this and even though this is a completely fake world uh well in the sense that it's it's extremely abstract yeah and what i find so interesting about ray tracing and path tracing potential is what it can add to simplistic visuals that's why quake 2 was so fascinating and why i think this works so well i mean you can take an old game like doom like quake any of those and by changing the lighting model it completely rejuvenates the game completely and you don't need anything complex to make it look great there's this also this uncanny feel here. It's like you're playing with Legos almost. And when I was constructing the structure, trying to make sure these rooms showed off effects that I wanted to show off, I had to think about it in extremely practical, real terms about how I was blocking off light and blocking it out or making sure that certain reflective objects are in a certain pattern. It was all natural. And I imagine as a lighting artist my goodness that looks so good as a lighting artist this would become so much a more natural process than waiting for it to bake out and seeing if it looks right or it would just be flat out more fun yeah gosh i had so much fun building this um but i think oh my goodness my wow does that look really good um i think going up just look at this bounce shadow over here this is like two levels of bounce to get that that's insane redstone to achieve this redstone you know is a it's a very key ingredient to the world of minecraft i know it's like they look partially permeable it's amazing looking um but so let's go over to the next room. This room, I wanted to show off another property of the global illumination itself too, which was I blocked off the lighting and had it hit specific... Oops. I'll talk about those too soon. Those are cool. But basically I wanted to block off the lighting so that it was only hitting a very specific material and we could see the Way it affects different materials. These are progressively darker and less specular materials So this one's like white and highly specular and so you can see if you look at the ceiling actually and all around it You know you get that specular Reflection yeah and the light bouncing off that material the gray one has less specular reflection in the bounce light. And the black, basically here, almost none at all. Exactly. And of course, this kind of highlights the limitations of the method here. It's very noisy, but it's still effective. The thing is, in general, very rough materials that are still a bit specular are really hard to get because the rays are super divergent and your performance basically quakes when you try and do it right. But my goodness these are interesting because the direct lighting for this version of the game that Sonic Aether made is actually using rasterization for the sunlight. So that is all rasterized specular right here on the block itself. But the candles are done fully through the path tracing. So this lighting right here it the block itself. But the candles are done fully through the path tracing. So this lighting right here, it's all path traced. No rasterization at all. Which, oh my goodness. Yeah, you can see the screen space element there with the lighting. Oh yeah, yeah. On the spec specular but it breaks down a bit with the screen space effect which you can turn off separately in the options but it's still pretty cool um i'm still looking back at this at this room with the redstone just look at this this is this is bananas i love this i it's like kind of mirror's edge looking exactly exactly what i was thinking but real just just and look look what it does to the blue by the way check out the blue area it's the color blue on your yeah this is apparently modifies this is yeah like this was green originally this was blue and when the lighting in the room has been bounced around in this red it changes the actual surface color that is something that is impossible to do otherwise uh yep i i this opens up so many opportunities i hope with this little bit of sun peeking through here you can actually see it sort of restores a bit of the green color i know right just there it is yeah touch like let me yeah remove that one look at that look so the top right corner here is like a different tinge of green than the bottom left is because of the bounce lighting. This is a consistent material. It simply changes through the lighting properties there. That's amazing to behold. Yeah. So let's go above really quickly and just turn back around and then I'll show off some other stuff that we got going on here. I kind of made this hallway just because I thought it looked hella cool to be completely honest absolutely light bouncing off this yeah I think we could use some candles here just to spice up the room a little bit gosh and just I just love the way is this specular from the wall you can see it on the adjacent wall. I know, right? You can see right behind you. And actually, if you walk in front of this, let's go in front of this yellow right here. I'm going to look at the yellow, and you pass in front of it with your avatar. Okay. Yeah. You should be able to see John's shadow crossing in front of the yellow every single time he crosses in front of it. Because his shadow is taking a part of the GI contribution, actually. His character model isn't, but his shadow is. Exactly. So there's a subtle change there. Yeah, it's awesome looking. But boy, my performance is, it's okay. It's like hanging right around 58 to 59 FPS. On an RTX 2080 Ti. That's a $1,200 US dollar GPU or something like that, right? Yes, exactly. 1080p, people. Let's do this. Let's go back inside. Woo-hoo. Come on, John. I believe in you. I'm coming. Okay, just down the mystery hall. Mystery hallway. This is taking some inspiration. This is what I like to call the Assassin's Creed effect. It is. When you first saw it on AC Unity when they did their interiors. Of course, that was entirely baked. But that's exactly what I was inspired by here by doing that. Just kind of trying to show that you can obscure the light and get all these indirect shadows everywhere. But this hallway is where I wanted to play with certain emissive properties that the GI enables. Like here, in this little room here, you can see how the candle is partially blocked, yet you can see its light bouncing all around the room itself. Even in the area behind where there's no light coming in directly from it, it's still lit. And as John walks past, you should see the screen space contribution of his GI kind of going in and out too, which is so cool looking. Let's see if I place a candle back there or a torch on the wall. It looks like Lego. It's amazing. It really is something special. Let's see if I place a little block right there What kind of block in that Be careful there is water above us we could flood the cavern by the way, so we have to be careful Want to do that, but yeah, let's go a bit further ahead. I created another two demo rooms down here Okay Yeah, let's go a bit further ahead. I created another two demo rooms down here. Okay. So the first one... Deep into the chasm....is here. If you can follow me, John. Yeah. And now we were talking about Quake 2. I couldn't help but make something that looked like it would be straight out of the Quake universe. This is so cool because the lava or... I forget. It's the redstone or whatever it is beneath us is an emissive texture and the entire block is counted as an area light and you can have an entire block of lava beneath you evenly lighting the entire space that's basically impossible with real-time lighting and games the way it's in now in rasterization because that's right it's usually done through a point light or some sort of like arbitrary surface that will not actually have the volume and it does all these cool things like create a grid pattern of shadows which will probably be lost on youtube honestly here but that's true this is very dark this is very dark red content so it's not going to look really that great on youtube but make a nice redstone wall over there and like look you can that beautiful specular yeah you can see that it stays in even if it's off screen john's specular reflection there too it's a bit noisy obviously given my completely low resolution here, but If you can imagine John's GPU using the RT core to push this to the next level that'd be really amazing, too It also kind of how you can create these natural shadows here as well. Yeah, right placing that wall there everything just feels Correct, and that's that's the point of all this is to create very natural lighting. Yeah, and It's very dark over there now, so let me place some torches for you. Align the wall there. There we go, it's all lit up nicely there. Do I have a shadow emanating from me? From your perspective? Yes, yes. It should be in screen space, but it should still look pretty sweet. It is, but yeah. It's there. So for those of you still with us yeah hopefully you're enjoying this tour through the land of path tracing it's uh it is a fun ride i think and if i have one last demo room very far below here there's a zombie down there yeah be careful okay let's head on down yeah oh wait i didn't actually fall it's okay now i'm descending slowly this room i wanted to show off color matching that it's an entirely room is there a zombie here i hear zombie noises oh my god this this is two different types of emissive blocks. One is blue and one is red. But when they bounce their light four times around the room, the whole room takes on a purple hue, actually. That's right. Which is mind-bending. But if you look at the specular reflections themselves for the blocks, well, they're red and blue. And this is something that you can't get in any game at all. And you can even block it off too well by doing this we sort of blend the colors together that's another thing you can see that there's a slight temporal component so when you break blocks sometimes that you can see through them it's a bit weird exactly hey it looks really cool but basically Sonic, when we were talking to him about this, he was describing how he could get the game much more performant if it was one probably using a more modern renderer other than GL, and if the shader pack allowed for some more, I guess I would say, custom programming. It's done in a very kind of blind way. There's not much that he can do about it to make it run better. But if this were running probably on DX11 or Vulcan, it would be... Oh my god, are we going to go outside here, John? I'm working on it. Oh god, it's so dark. Where are we going? Oh, I hear the sound of... Oh, there we go. Wow. Glorious light. We made our way out. Shall we fly around the world and see what we can do? Yeah, take a look. Yeah. I mean, there's a lot of cool, like, natural things that happen. If we find a cave, that'd be something really cool. How about you... Let's go over here and check out all this water. Actually... Where'd you go there John? Yeah because we haven't really showcased the water reflections. Oh yeah that's so we've been always kind of looking at kind of glossy reflections but the reflections can be extremely sharp. If you look over here, you can see everything reflected. That's right. And actually if I go on to the other side, you should be able to see John reflected in the water too. And I see you reflected right there next to that moving lava bit. And yeah, it's just a perfect mirror-like reflection. If you look along the edge of the screen, you don't get any of the typical SSR artifacts from those reflections, but you do get it from the dynamic objects, as you said. Yeah, yeah, yeah. But still, it's amazing. All dynamic objects seem to use screen space, while the static world, well, mostly static. What are these cows doing? Oh, no! They're on fire. They're on fire. They're on fire. Oh no! I mean... So, there's a cave over here as well. Oh, is there? Yeah, that was a small one. Do you remember Doom? This looks like diminished lighting in Doom. It absolutely does. Which was best on the Atari Jaguar. Yep. Next to the CRY Color. This looks, uh... Yeah, you can see the individual bounce light from here going like this and you can modify it a bit. Oh my God, this is yellow black. Bye-bye, John. Hey. And are you placing some lighting in there? Yes, it's well lit in here. And are you placing some lighting in there? Yes. It's well in here. And if I do this, you should see it pouring out. My goodness. Look at this. It's like gelatin. I can still see your name through them. That's really weird. But yeah. Basically, everything real time, everything looking very interesting. And running... How's it going there? I'm kind of lost in your maze of... I'm behind you. What? See, the magic of Minecraft. I am now a magician. I love how you can see the noise here on this yellow block. Yeah, it does make you kind of wonder what further variations would be like this in the future. How much more performance Sonic Ether can extract from it, getting it to run better, because obviously 720p30 on a nice GPU like this is a bit sad. But I hope it gets updates in the future. My goodness, look at this. Reflections here. And yeah, we're looking at a very standard map, really. This is just a generated map with some changes we've made. If you actually load up on some other servers where they've done a lot of work to build out these beautiful cities, it benefits a lot from running with retracing enabled. And I just love the sun glare in the distance. Looking at these reflections, it really is just a beautiful, beautiful thing. It completely changes the look of the game. Yeah, I mean, Minecraft is known for its low-res blocky graphics, but all of a sudden it's like real-life Minecraft. But yeah. It's just too much fun to play around with. Is there anything else we should do before we close out this, uh, session? I guess, uh, maybe we can try to build some more random structures. Try and build. I mean, what's the typical Minecraft structure before you started up as always a house to keep yourself alive in the night. I guess what I could do. Watch that. Why don't you come up and join me in the night, I guess what I could do... Why don't you come up and join me in the digital foundry sky tower that I'm constructing. Oh my god, my GPU is about to keel over. 80%. I'm also at 80%. And all these are emanating with red lighting. Yes, of course. That's super silly. It's akin to RGB lighting. Oh, my goodness. But yeah, as you can get the point, basically. Building the special digital foundry tower the one ray tracing enabled the is much more fun than it was in apex legends that's right this is this is uh legitimate it does make me wonder actually if we could see something like this on next gen consoles what do you think there john like something like this i mean it's running this is still running in real time on my rig and I think it's almost worth it for a game like Minecraft it doesn't need super resolution I agree I absolutely think that I think that this is a perfect example of the type of ray tracing we or path tracing we may see on next generation consoles uh maybe simpler games but also you know with a lower performance target if you're happy to target 30 frames per second and you take make some smart decisions, fake a few things you know you can do some some amazing work. That's kind of the way I see it right now too. I mean obviously Minecraft is not the same as Metro Exodus in terms of world complexity, but darn if it does not look that much better as a result of being patristic as it is right now. I agree. And we have all these, look at, I just love all these nice natural shadows. I like the corner darkening. Like, you can get, whoa, what? Oh, yeah. It's floating. Oh, these are half blocks. Oh. Yeah. I understand. Exactly. So I could build some windows. Not the Microsoft variety. Well, if you want. I mean, this is a Microsoft published game. No doubt. Yeah, and they still sell the Java version, which was completely foreign to me. But here we go. Wow. You can see it's like progressively darkening the shadow here as you build out more of these things. Yeah, that's amazing. But yeah basically Minecraft path traced running in real time on the GPU, amazing looking, shows off a lot of really cool effects and it's probably only gonna get better in time and I hope that you can try this out for yourself. This version of Minecraft is still available to be purchased and yeah I say give you can try this out for yourself. This version of Minecraft is still available to be purchased. And yeah, I say give it a try. It's going to... Absolutely. I think I may actually end up using this in further videos to explain lighting techniques. It's that good. Yeah, this makes for a great demonstration that's all done in real time. But yeah, so if you are still watching this for some reason, and I'm not sure why, I hope you did enjoy our video talking about how patch racing works in Minecraft here through this mod from Sonic Aether, and maybe learned a thing or two along the way. And if you did enjoy it, hit that like button and subscribe to the channel. If you're already a subscriber, well, hit that little bell in the corner to be informed, if you really want to, to be informed as soon as digital foundry posts a video we always like that and uh yeah write a comment below about what you think about john's building skills here i mean just look at this tower they're they're okay if you guys wait the the finale is coming yeah yeah oh yeah there we. And this is John and Alex. Signing off.