Coding Adventure: Portals 

"The reason for the traveler's unfortunate demise is that this function that detects when an object leaves the portal depends on the internal physics loop which runs on its own fixed timestamp" Me, eating unsalted peanuts and has never coded anything: A rookie mistake

"Filled with grief and rage, I began debugging." - Every game developer ever That is such a big mood

Do you think the guys behind supposedly calm and chill programming channels actual freak out and break shit when they've been stuck on a problem for a long time? Like, he says how he had an issue, so he found an article with the solution, when in reality he tore his hair out searching google for hours until he misclicked on a link that luckily had the solution.

"The code for this pretty simple..." Me: Sees Vector4

"The code for this is actually quite simple." Proceeds to execute rocket science.

Portal (the video game) uses a hybrid approach to recursive portals: the first few iterations are drawn using a recursive camera technique (like in your portals), but the initial texture is a scaled and distorted version of the previous frame. The effect looks pretty good, but there are some cases where it breaks down, like when the portals are not at 180 degrees to each other, if they're too close, or if they're drawn at a sharp angle on-screen. It definitely beats having a black texture, though, and looks passable even with only 2 or 3 "real" levels of recursion. It really helps sell the look on low graphics settings, and it's very important in Portal 2's co-op where having player 1's portals + player 2's portals + water reflections + shadows + splitscreen/partnerview means there can be tons and tons of rendering passes. Objects partway through portals use a "clone" approach (also like in your portals). The clone has limited support for physics, and tries to transfer forces applied to it to the real object on the other side of the portal. It doesn't work very well and looks "spongy" if you try to break it, but it at least prevents you from making things intersect and dropping things inside your own hitbox, and works best with simple cubes which is what most of Portal's objects are anyways. There are some physics optimizations: objects close to portals don't collide with anything far from portals, objects far from portals don't collide with any clones, and so on. Oh, and to make the portals appear oval-shaped, it just draws an oval to the stencil buffer and hides the seam with the rim texture and particle system. As far as physics are concerned, the portals are rectangular. (My source for this is a great talk given at some school by Valve graphics and physics programmers, but I can't seem to find it anymore!)

I love coding videos for this reason: "I also got sidetracked and started drawing clouds." "No time. 7 min in. gotta get to it."

When ever I get frustrated at work (working on the software engines that run artificial intelligence), I come and listen to Sebastian. He's so calm about coding and debugging that I nominate him the "Bob Ross of Software Development" 😁 Combine that with his self-deprecating, deadpan humor and it's a pure delight watching (and re-watching) these videos.

This just proved me how insane valve was when they made portal

"The maths went way over my head" Me: nods along

"I got a bit side tracked by making some low poly clouds" There is something lowkey hilarious about everything you say Seb.

3:30 It took me a few moments to realize that this was, in fact, not editing, but something you programmed into the game for the sake of visualization Super well done, I learned a lot!

I hate that you made this video after I spent the last four weeks looking how to do it. Also love you thanks.

"The maths went way over my head" Me, seeing simple vector multiplication.

Sebastian: *coding 4D planes* Me: *getting errors coding Hello World*

I understand maybe 6% of each coding adventure video and just keep coming back to remind myself how much more I still have to learn

"It's seven minutes into the video and you still can't walk through the portals" "Overcome with grief and rage, I began debugging" "I'll cue up some old-timey music so we can sit back and watch the result" This is not only one of your most educational videos, but one of your funniest to date as well. Coding Adventure is my favourite dev series on RU-vid

I personally think foggy portals is a great solution to the recursion problem! Could also add a blur filter at each subsequent iteration to make the end of the recursion less noticeable. Beautiful work anyhow!

I know you have a Coding Adventure: Clouds, but could you post a tutorial on how you did those Low Poly ones? They're beautiful

"But we have no time for this. We are 7 minutes in the video and still can't walk through portals" (c) I love this man! Each and every tutorial is full of useful stuff, clear explanations and don't waste the viewers' time. I wish all the RU-vid tutorials were so awesome and respectful about the time!

Whoooaaa that was amazing :o

7:10 those are some nice clouds

"While I've been writing this, the car's been struggling tremendously to drive over a little rock. 10/10 for effort, though." This kind of thing is what makes your channel fantastic instead of merely great. :)

this guy is a legend in mathematics and programming, super inspiring for everyone such as me

Using a 3D object on a 2D Screen, to project a 3D object onto a smaller 2D Screen, which is apart of the Original 3D object projected on the 2D Screen, projecting a 2D object that projects a 3D Looking object? *Makes sense to me.*

Insane work put into this. Writing shaders scare me but this was so great.

I honestly want you to make a library out of this, so nobody has to repeat this painful endeavor.

Guys If u want to use this in HDRP or URP its really easy. I got working portals in both. In PortalTravelers change line 56 from foreach (var mat in renderer.materials) to foreach (var mat in renderer.sharedMaterials). In MainCamera change line 11 from void OnPreCull to void LateUpdate for URP enable the Post Processing checkbox under each portal camera. (Main camera doesn't matter) for HDPR I did not change anything. * Found this solution on Github but just wanted to share here. *Using 2021.3.15

This was a triumph! I'm making a note here: Huge success!

The fading to black is how mirrors work IRL, so that makes a lot of sense. Edit, for all of you saying "but it's not a mirror." The point is to make be more sensible than "oh it just cuts off at a certain distance." It doesn't even have to fade to black across so many iterations, maybe just the last four fade to black.

Now you're thinking with portals.

There „camera box“ absolutely blew my mind

You could add some *magical* distortion instead of the fading out effect . Like water distortion or blur that starts from the second portal and scales up.

For the recursion problem: The guys from Valve "solved" it by just re-using the rendered texture from a certain point on, e.g. from a depth of 3. They then distort them to make them warp out of frame. This does not look very realistic, but People won't see it if you start re-use at a depth of 5 or so... Depends on the size of the portals and the details in the scene of course.

Videos like these are one of the reasons why I constantly keep falling in love with game development. I just discovered your channel, and within 2 minutes, I was subbed. What a well done video!

I wonder how he's going to add this concept to his solar system project... Wait. WORMHOLES!

The editing on this video is phenomenal absolutely enjoyed everysingle part of this video

"Alleviate the GPUs suffering...." Chuck that bad boy into even more complex math solutions.

The music for this video is set up like a horror movie, love it.

god bless the internet

Amazing! When I was doing my course project on game development, I wanted to implement portals. I researched for many weeks, arriving to the same conclusion as you for the camera movements, clone on teleport and the screen texture cutout, but you went above and beyond in implementing the portal within portals rendering, and the trick of making the portal surface a cube without back-face culling absolutely blew my mind! Thank you for all this great education.

That old automobile casually rolling off the cliff with the classy relaxing oldtimey music in the background... Lmao

When you think when he explains stuff with animations and you see that he actually coded it to explain

Aperture Science's computing department is really going above and beyond

I lost my mind at the model cutoff , you go way beyond ! Cheers !

Still not perfect, the hardest part remains : lighting. Let light go through portals

Valve: our Portal series was really hard to develop and unique! Sebastian: hold my adventure.

im just making this a comment for whatever fix i find shader fix in the properties section below the _InactiveColour ("Inactive Colour", Color) = (1, 1, 1, 1) just paste in: _MainTex("Base (RGB)", 2D) = "white" { } teleport rotation fix if you walk through a portal and your rotation snaps, thats normal, but likely not wanted. if you copied the project directly from the repo, you shouldn't have this problem, but here's the solution: in your movement script, switch the inheritance to PortalTraveller then paste this function somewhere public override void Teleport(Transform fromPortal, Transform toPortal, Vector3 pos, Quaternion rot) { transform.position = pos; Vector3 eulerRot = rot.eulerAngles; float delta = Mathf.DeltaAngle(rotationY, eulerRot.y); rotationY += delta; transform.eulerAngles = Vector3.up * rotationY; Physics.SyncTransforms(); } if you paste this and do nothing with it, it likely wont work. this is because i might use a different variable name than you the rotationY is probably going to be the only different variable, this variable is for the camera's Mouse X: rotationY += Input.GetAxisRaw("Mouse X") * sensitivity * Time.deltaTime; also, the Physics.SyncTransforms() fixes another problem, which was if you used a character controller, you wouldn't teleport :D

Almost thought I had KSP open in the background >___>

My reaction when i see a new coding adventure: *screams*, "Wow another one!"

You are an absolute legend and my idol for problem-solving and coding in general. I agree with what have been said previously in some comments here: "You are the Bob Ross of coding."

This took a lot of troubleshooting for me to work out, but after a several attempts and a lot of troubleshooting I got this to work better than I had ever had portals working before.

We are blessed with this video

While I'm only a simple gamer I really enjoy how you show what goes on behind a game mechanic. The most coding I've ever done was visual coding with the Unreal Engine. Following tutorials and messing around with what I learned.

You are doing a really great job! To make people UNDERSTAND something instead of just showing what you know! One of the best channels I found in these days to keep learning. Keep growing.

Genious! I love how you document every special case and point that I'm completely unable to guess at first glance making yours, the best tutorials I've ever seen. Congrats dude! You makes this feel so easy to do!

6:20 KSP music then you acheve space)))))) So many memories.......

Can you answer the age old question of what happens when a moving portal falls onto an object? Does the object go flying out the other side with the same velocity of the moving portal, or does it simply plop out the other side?

I love how simple and straight forward this guys work is. Nice job sticking with the KISS method!

Sebastian, you're hands down the best Unity resource on RU-vid. Keep doing what you're doing!

11:10 imagine a game that's only shadows like that would be really cool

This is amazing! I’ve seen many people code their own portals, but this is by far the best one I’ve seen!

You're a mad lad. Thank you for displaying your journey for each coding adventure. It's really interesting work.

I love watching random Unity videos with random cool mechanics, cause even though this portal stuff is something that I'm probably not going to implement into the game I'm working on, you actually gave me a perfect solution for an issue I was running into with deciding which way my player should be moving down a zipline when hooking onto the zipline from anywhere that's not either end point!

Awesome... I have been looking into making portals for a few years now, and this is the most complete example and explanation I have found so far dealing with pretty much all the problems you can run into. Except getting light to work through portals... but not sure even Portal got that implemented.

Those LP clouds though! How? You are awesome Seb, thanks for the video!

This blows my mind. Explained like it’s so simple. Great effect.

Absolutely amazing watching you chip away at the issue you face when creating something like this , I have been coding information systems for 13 years now , but this is next level

I wonder how you would solve the problem of the possibility of AI seeing through the portal. Nevertheless, thanks for the great video!

I always love seeing these in my subbox, great stuff man!

the portal game tutorial was the first of your videos i ever watched, and it at the very least got me to think about math and projection in 3D space as a 9 or 10 year old. very fond memories of my early days with unity :) you are an absolute master with your shaders and procedural mesh stuff. such an inspiration, i love the nature of your work.

This is the best implementation of portals I've ever seen in unity. Making the "portal" a cube and slicing the 3D object blew my mind when I saw how well you solved some of the technical limitations I'd ran into previously. Simply amazing.

15:47 GLaDOS voice from somewhere in the Room: "Now you're thinking with portals"

Fantastic stuff! Love the detail and thoroughness you put into your investigations.

I like how you can make coding and complicated concepts like this into actually interesting and engaging videos. Thank you very much!!

Apart from this whole video being great and really interesting, I love the end sequence too. The way the blocks fall through the first portal, with the second one angled so they go through the first again, but at a different angle so they exit the second at just the right angle so they fall back through the second out of the first and then, my favorite bit, the yellow one hits the tree with a gentle thud. Absolutely beautiful! Did that take long to set up, or just happy accident?

8:43 me when i try to do literally anything

I've been having some ideas of how to use portals in a horror context lately but I wasn't sure how much effort I wanted to go through for a relatively minor effect, but this project will help me a ton in figuring it out

This is by far the most comprehensive portal implementation I have seen. An area of improvement would be lighting through portals. Very nice work!

I am so thankful for your documentation of your progress. I really wish I knew how to understand the maths behind all the projects you do accomplish. Im just a simple ReactJS web developer and I have absolutely no clue where to even begin to learn any of this. I really want to become a solo game developer and clearly have a long journey ahead of me. Im happy I subbed as there is so much stupefying content on this platform and it's a breath of fresh air to watch this type of content, keep up the great work.

"wait, did I open ksp in the background on accident?" ... "oh, same royalty free music. Got it."

I'm always amazed at how entertaining these videos are.

Your videos are just lovely. You take such care to explain things so well. Such a lovely sense of humour. Such a joy. You inspire me. :) Thanks for all the hard work you put in. I'd love to see a behind the scenes on your process. It feels like it must double the effort at least. It's much appreciated.

I come back to this channel often, but I often think Godot is more aligned with Sebastian's vibe. Unity seems like it has more technical support so maybe it's a situation of having less potential road blocks toward ideation. Easier flow state because you avoid running into engine problems. Who knows.

I just felt completely stupid after watching your programming skills.

This has been an amazing journey. Also, your video editing skills are fenomenal!

Thanks for walking us through all the issues a seemingly "simple" portal throws at one. I enjoyed it very much.

You should do a Shader programing tutorial Series!

Omg u might be the most hard working dude on yt learns blender and unity how to code and write algorithms to visuallize the code and edit the video all with commentary. Like wow that’s a quick sub

I really love how in-depth this is. Keep it up!

I love this video. Please continue with the portal stuff, and the quality is seriously mind blowing. Amazing job :)

Coding Adventure: Aperture Science Handheld Portal Device

This channel is, frankly, too good relative to the number of views it gets. Something is clearly wrong with the world. I'd love to see you cover non-Euclidean space rendering (à la Stanley's Parable) where you can walk down an entire hallway/region where space is compressed or expanded. But it seems like it'd require ray tracing to get the visuals to behave properly. Also, I'd love to know how proper ray-tracing would account for portals.

The fact that you share all your project files for free is awesome.... Thanks man.

This one took me right back into my GC course in university a couple of years ago... I really love your videos and they make me wish for more time to play around with unity too. Sadly my job has no relation to GC stuff at all. I wish I could spare some free time to do such awesome stuff like you! Keep up the good work!

I am so happy that I stumbled upon you, now I can try to reverse engineer it

Looked at the description and said it in GLaDOS' voice "Experimenting with portals, for science (you monster)"

Thank you for the tidbit about `w`, I haven't seen such a casual / clear presentation of the mechanics presented anywhere else.

I love how condensed your code for moving the camera is. Other tutorials have at lease 8 lines and use quaternions and stuff. You managed to get it done in two lines!

я вообще не англоговорящий. Но подписался, совести ради! i am not english speaking. and watch the translations of your videos. signed up in good faith! Thank you, google translate. Did I write it correctly? I will never know..