How I Implemented Shadows in my Game Engine

[@CodingDragon04]

I have actually missed this more technical content a bit. Concise yet excellent explanation!

[@pivotal-ai]

Yes these are wonderful and I learn so much. They're the most inspiring for me to work on games of my own. Since it feels much more tangible. Love to see more!

[@landru27]

I, for one, feel that this video was much more than just "a little bit interesting"! I gain a lot from you diving in on the technical details. It's particularly interesting when you cover how your approach to a certain graphical problem has become more sophisticated over the course of time and your projects. ... Don't get me wrong, though : it's also always great to see the dishes you cook, your balcony garden, and the landscape around where you live, like in a regular dev log! 🙂

[@mr.norris3840]

I agree

[@UserUser-sh6wi]

Agree on the first half, but must disagree on the second. I find devlogs to be much more enjoyable when the irrelevant parts are cut out and all the focus is on the project.

[@ceyhunuysal9509]

Im literally watching for the cooking!

[@Danuxsy]

With path tracing you don't have to deal with trying to fake all of this, it just works.

[@mr.norris3840]

@@Danuxsy But it still isn’t 100% accurate, and a lot of restricting assumptions have to be made

[@MattieBW]

"technical and boring" sounds good to me :)

[@cineblazer]

I really really love technical content like this. Maybe it's not the most popular amongst other subscribers but I'll always watch it! Super fascinating to someone like me who doesn't have any graphics programming experience but wants to learn.

[@Krahfty]

From my experience, a lot of this kind of stuff is just the trial and error from normal development, get your hands on an engine and just start making something, you'll soon encounter these kinds of problems and you'll learn directly from trying to fix those types of problems 1st hand

[@jdh]

Another fix you could try for the shadow shimmering on movement is to add a small offset to the projection matrix for the shadow map that ensures that all world coordinates will always “snap” to the same shadow map texels, IIRC done by taking a fixed world space point (the origin) and transforming it into shadow space and then finding its offset from the center of a texel in shadow map space (where the texture sample round to) and using that, transformed back into shadow projection from shadow texture space, to offset the projection matrix. maybe a little complicated though when you already have a good enough solution :) the graphics are looking great!

[@Assassin_Droid]

Helo there

[@ThinMatrix]

Thanks for the idea, that makes a lot of sense! I'll have to give that a go next time when I work on the shadows :)

[@Dannnneh]

Always nice to see your insightful comments.

[@mrdiabeatis9943]

didn't see you there vro...

[@AjAce19]

I really enjoy this kind of video! I know you can't always do technical stuff but its really interesting and cool to see stuff more in depth!

[@massimogalliano8337]

Seeing your project and this game take shape is heart-whelming!

[@oamioxmocliox8082]

;)

[@erikbrendel3217]

Have you heard of "Variance Shadow Mapping"? This is a simple mathematical way of achieving very smooth shadows without the need of introducing many samples, and it also solves the shadow-acne problem. Maybe this would be worth exploring for the game... :)

[@MrAchterbahnfahrer]

Just an additional note to anyone reading the comment above: If you're considering variance shadow mapping, you should also take a look at moment shadow mapping. While variance shadow mapping only takes the first two moments of the distribution of depth values (i.e. their mean and variance) into consideration when calculating the shadow density, moment shadow mapping uses the first four moments, thus reducing the issues of light leaking caused by variance shadow mapping.

[@henryford8433]

Ok, I am a botanist, a retired plant population biologist, and I and a botanical artist wondered why people are plant blind, and discussed the potentiality of games based on plants, and Albert Durer’s turf, and the immersive Van Gogh exhibition in Bristol. Your ideas are interesting and I might come back for a chat some time. Henry F

[@dekira3545]

can i know how the game project is going?

[@Grimille]

One thing that was noticable in Equilinox and is curently noticable in Homegrown is the shadow movement not going along with the windy shader. Good video, I prefer by far when there is also technical involved in the video ! 😊

[@ThinMatrix]

I've updated the Homegrown shadows so that they now sway in the wind too :)

[@Grimille]

@@ThinMatrix great work ! 👊🏻

[@enotirab]

Loving the series. For what it is worth some of us love "technical and boring."

[@SomeNussi]

Here's what i can recommend for moving/resizing the shadowmap: keep it a bit bigger than the view area AND re-calculate it every frame (if the camera didnt move, you keep the current "target") instead of fully applying the "new" dimensions immediately, interpolate between the old and the new one in a ratio of about 85 to 15 with the new one being 85% responsible for the new image. This way you're getting rid of the sudden shifting and you're able to keep the shadow maps size much smaller than previously, improving the shadows quality

[@ThinMatrix]

Thanks for the idea, I'll give that a try!

[@cribalik]

I recommend 'jdh's answer instead, it's the fastest and arguably simpler than any other method. The idea is: only move the shadowmap in increments of its pixel size (in world space) docs.microsoft.com/en-us/windows/win32/dxtecharts/common-techniques-to-improve-shadow-depth-maps?redirectedfrom=MSDN Something like: bounds = CalcShadowMapBox(); // in worldspace float texel_size_in_world_space = bounds.width / shadowmap_resolution; // assuming shadowmap is square // snap to grid bounds.x0 = floor(bounds.x0 / texel_size_in_world_space) * texel_size_in_world_space; bounds.y0 = floor(bounds.y0 / texel_size_in_world_space) * texel_size_in_world_space; bounds.x1 = bounds.x0 + texel_size_in_world_space * shadowmap_resolution; bounds.y1 = bounds.y0 + texel_size_in_world_space * shadowmap_resolution; projection = ortho(bounds.x0, bounds.x1, bounds.y1, bounds.y0, bounds.z0, bounds.z1);

[@davidberry8275]

thanks very much for taking the time to do this. Love the insight of 3D graphics. While I'm a decent programmer this is outside my normal area of business applications. Its amazing how much processing can take place in every frame using GPU, while our business app processing seem very slow in comparison.

[@Seff2]

Wow I never have seen such a high level explanation on how shadows work in 3d games. Thanks for this vid!

[@Mystixor]

Been using the basics of your old Shadow mapping tutorial in my own engine ever since. Some of these ideas you shared today are definitely worth looking into!

[@garole]

Thanks for the helpful video! I was experiencing similar shadow issues in my project, and this really cleared things up,

[@SpikeStudio]

The solutions you come up with are always incredible

[@recyclebinladen5903]

Lol what? What do you think AAA games are made of then, and since decades?

[@_miyu]

I really like your work on the shadows, especially reducing the calculations with an over sized box. I have a suggestion about how watering the crops gets rendered. Instead of the full square turning dark immediately, think of how rain, or the watering can would drop random droplets until it all gets filled in. It could be a quick animation that just darkens randomly sized circles until its all watered. Hope that helps, thanks for the great dev videos.

[@ThinMatrix]

Thanks for the suggestion, that does sound nice!

[@MrA6060]

it was looking great with the last graphics but now? holy smokey this is amazing. keep it up

[@ryanwood9288]

Dude thank you for everything. Seeing your videos pop on to my timeline really brightens my day.

[@elingranath]

As someone working on my own engine, videos like these are super interesting and I even prefer them a lot over the regular game dev videos since I already have a lot of experience with game programming. I'm just about to get started with shadows myself so this was a nice surprise to see in my recommendations!

[@hernestpoissin6964]

Hello ThinMatrix, I have started game dev with your OpenGL series and have learned a lot with you. Thank you! You do great work. For your shadow shimmering, what you need to do is to move the shadow camera by fixed increments, which correspond to the projection of the shadow texels on a horizontal plane. This completely removes the issue. Don't hesitate if I can help you back.

[@nhuvunguyen4525]

The only bad thing about watching your dev logs is that they inspire me to drop everything and make my own game engine

[@GingerBeker]

Amazing. Really few people can really know how difficult this stuff are. You rock!

[@kiki-drawer2669]

I don't code or create games at all but the way you talk about your work and explain simply means your videos are never boring no matter what element you focus on! I enjoyed this video just as much as all your others! Ty for working so hard!

[@GamesBySaul]

This was super interesting honestly! Seeing how you go about tackling issues, to me is very cool, it's nice to see your train of thought with it all!

[@otoS97]

Game looks amazing, I'm so happy after the graphical upgrade

[@bertrodgers2420]

really enjoy the more technical videos as well as your normal ones. Would love to see more about what frameworks/libs you've used too

[@zeztro]

I really enjoy these little updates. The content is laid back and I always look forward to seeing how the game is coming on.

[@AxisCoords]

Love your devlogs so much

[@felixstrau7880]

As a hobby game dev, I really enjoy this type of content. You don't have to go more into detail. But the overview of your thought process when implementing this features is really helpful.

[@alexgravenor]

One thing! Because it's outside, you actually might want less soft shadows (the sun is so bright and parallel, it's shadows are typically quite sharp). You may be able to do that with a cutoff on your sampling

[@kylemason01]

Each step you make, the game just gets better and better. Keep it up!

[@MichiGombocz]

This might be the best video by far done by yourself. Thank you for all the effort you put it every time, it pays off for the viewer and hopefully yourself as well!

[@DarkFazy]

This video was great, thanks so much. Both relaxing and also explained some ideas behind implementing shadows quite well.

[@hopperpl]

We use an additional approach with 2 shadow maps... the first is the wider scene which creates the pixely shadow map (the one you use), and a second is a narrower map which only contains a small part of the scene using a distance field around the camera (not the light source). Both maps are generated during the same rendering pass, the shaders just use 2 rendering targets. The 2nd map has a much higher resolution, you can think of it like a 2nd zoomed shadow map. During the final render, the shadow is then, based on distance again, sampled from the narrower or the wider map. This generates nice sharp shadows around the "camera" while having only blurry shadows far away, which you wont notice in the distance anyway. As a disclaimer, this will only work with 3rd person or 1st person rendering. For this game with a wide/far camera, the distance value for the narrow shadow map will be too large and the difference in shadow map resolution too small.

[@mischa7823]

I do like the devlogs that go into technical detail a lot more.

[@CodeParticles]

I remember getting into shadow mapping, and then later omnidirectional shadow mapping! I've been avoiding those concepts lately but it's only a matter of time before it's needed again, thank you for reminding me!! 👍👍

[@George-si6iv]

So happy that you are doing consistent uploads now! Been watching since you were developing Equilinox and watching your dev logs has never gotten boring!

[@zachj1196]

The shadows look so good! Even if it was a more technical devlog I love to see the progress on the game!

[@sydryan9589]

This is so fascinating, love your videos my man.

[@_v53]

Shadowing is so tricky but so satisfying. It was arround here I reached the end of my efforts to develop my own engine (i'll return to it - when time permits!). You've got a great workable solution here.

[@martinx9027]

YEAH! Love this kind of insights of more technical stuff of the game, looking really good so far, Keep it up!!

[@StephenLebed]

This was a really great video. I always enjoy your vids and would like to see more technical discussions as you go forward.

[@asherhaun]

This is the kind of devlog I subscribed for in the past. :D

[@NeilRoy]

Fascinating insights on how to do shadows. This was a good, general description of the problem, I like it.

[@bejoscha]

Always interesting to see the technical details. Thanks.

[@eboatwright_]

Very interesting! Never even tried to write my own 3d renderer, kudos to you for adding this!

[@lucidmoses]

Now that you've done that, shadows from clouds should be pretty easy to add. Not sure it would be all that useful if it's not tied to groth or something but may make it look a bit more realistic (If that's what your after).

[@AntonioNoack]

They add a new issue: clouds are typically transparent/translucent, so he best should do them in a separate pass, and then blend them with the normal shadows. Given that clouds may be procedural, and you probably can't see the sky anyway, you could completely do them in a shader function, and save the cloud shadow map.

[@weinsim3856]

Wow, the graphics are starting to look really good

[@JackTraynor14]

Great video. I hope you can do more technical devlogs like this in the future.

[@DEPHi3]

I really like this kind of more technical videos. Good work.

[@bigmistqke]

Waw the steps u made in the last videos really added a lot of life to the scene!

[@falcowinkler2429]

super interesting video. I love the deep dives into technical topics. so informative and very well explained!

[@Arkogelul]

Even if this one not the regular format, I really enjoyed that video. Thanks!!

[@KamranWali]

Awesome video! The shadow rendering already looks awesome. Really like how you go in detail to explain how each of the problem was tackled. Learnt something new today :) Looking forward to your next devlog. Keep it up! :)

[@ThinMatrix]

Thanks, glad you liked it :)

[@Skeffles]

Fascinating to see how you approach shadows!

[@gnramires]

Here's an idea: sample (say 7 or 9) lightmaps with a slight angle offset. The sun rays are approximately parallel at Earth, but the Sun does have a small apparent diameter, of approximately 1/2 degree (10 milliradians). By sampling the shadowmap in a "hexagon" of radius 1/4 degree (you can exaggerate this effect a few times for dramatic effect), plus maybe a point in the center, you get very nice soft shadows that also have a distance effect (they're softer when far from blocking objects). You can also achieve this by computing one shadow at a time (for a total of 7) like you're doing but averaging out the 7 results. Very interesting video, thanks :)

[@Xbookdetemprano]

Seeeee, me encantó! Sos un genio. amo aunque sea estos videos cortitos que son muy interesantes para aprender y motivarse! Muchísimas Gracias por el esfuerzo y la buena onda!

[@williamist]

love the technical videos :D

[@simon-wt]

I haven't commented yet but this time I really want to just show you my gratitude for your work. This video is actually one of the most interesting videos I have seen yet! In graduate school I studied a lot of computer graphics theory and I really appreciate watching you implement these techniques and algorithms into your game. I Especially love the commentary you give and it's really nice to have the direct feedback on the game. Thank you Karl for taking us with you on this journey ❤ PS: I only watch around 2-5 videos a month but I won't ever miss on watching any of yours!

[@AntonioNoack]

@6:48 this can be fixed, if you just add the bottom of the tree stump to your mesh Thinking about it: you even can move the tree a little down (or extend its roots), and it will be fixed; assuming you render the ground to the depth texture, which isn't necessary unless it has bumps steeper than the angle of the sun.

[@Botondar]

For PCF filtering: It looks like you're strictly checking whether each sample passes the shadow test or not, which means that A) you can only ever get a handful discrete values which depends on the number of samples you take and B) all the world-space fragments that land on the same texel in the shadow map will have a uniform shadow value which results in the blockiness. What you really want is to also weight the contribution of each shadow sample by how far it is from the actual location you're shading. In the case of 2x2 PCF filter for example where you have: |a, b| |c, d| you want to compute the shadowing factor with a proper bilinear filter, i.e. mix(mix(a, b, u), mix(c, d, u), v) where u and v are the bilinear weights from the bottom-left texel center, and a, b, c, d are 0.0 or 1.0 depending on whether that particular texel passes the shadow test or not. If - as you mentioned - you decide to use the built-in shadow texture functions in OpenGL then this is how it will actually compute the shadow weight, which should automatically give you nicer looking shadows. You might not even need to jitter the samples.

[@FloWritesCode]

Great video! Shaders in general have always been my weakness, so this was very interesting to watch :)

[@Sopiro]

This video makes me nostalgic when I was watching the opengl tutorial series you made! Awesome devlog :)

[@madao7865]

Looking good. Also, the technical side is quite interesting.

[@marcelbricman]

i love this technical material! even though i have an engine to do shadows for me, it it lovely to see these nice tricks ❤

[@0.lennart]

I always enjoyed watching your tutorial videos a few years ago. It's impressive how you improved. I would love to see a few new tutorials when you have some time. Keep up the great work :)

[@NICK....]

I wonder how a game like this would look like with uber photorealistic rendering, like all the bells and whistles: Raytracing, volumetrics, PBR, 4k textures, models so detailed you can zoom in and see the individual bugs crawling around on the plants

[@Joern290]

Great video! Love the art style and the shadows! 😊

[@thehambone1454]

Great video, glad you made one on this topic, I am going to to do some similar techniques for shadows after watching this! I like the art style a lot btw!

[@MrOmega-cz9yo]

As others have mentioned, I too like these types of videos! Thanks!

[@dennismakesgames]

Lovely, I do feel like shadows that are softer would really fit the art style, like Tunic, and the clouds that casts shadows would also be lovely :) Great work as always.

[@VetorDigital]

This is beginning to look nice, you are on the right track.

[@Phvli]

Good, concise explanations for the basic concepts! You'll probably want to look into Cascaded Shadow Mapping if your single map resolution is not enough.

[@Zyhorn]

Very fun and interesting. I love the technical explanation and wouldnt mind ever more 😀 thank you

[@LifeOfMohammed]

Awesome work! Love the shadows!

[@Simon-ik1kb]

loved this one. Really like those a little more technical videos. I understand basically... nothing. But still very interesting.

[@DarxDev]

for shadows, either just add a bias with front face rendering or add screen space contact shadows with back face rendering to get rid of that gap

[@VegetableJuiceFTW]

I have always wondered how shadows are done. Neat!

[@SSouper]

you can also use variance shadow mapping, where hardware effects like linear filtering work out of the box so you can get them for free and you can do a quick blur of your shadowmap using a render to texture pass. Also a quick and lazy fix for 5:52 in case everyone needs it: cast your shadowmap camera's position to an int :)

[@MrAchterbahnfahrer]

Just an additional note to anyone reading the comment above: If you're considering variance shadow mapping, you should also take a look at moment shadow mapping. While variance shadow mapping only takes the first two moments of the distributions of depth (i.e. the mean and the variance) into consideration when calculating the shadow density, moment shadow mapping uses the first four moments, thus reducing the issues of light leaking caused by variance shadow mapping.

[@blubloos]

Amazing dev log as always

[@leoingson]

One of your best videos of late! Tech content rules :)

[@kamathonxander1]

This was super interesting, thank you. Please do more of these technical in-depth videos in the future! 😊

[@Draconicrose]

They look pretty good and I learned something more about development from this video.

[@peterhickman386]

Along with the graphical upgrade it is looking much better now. Also nice technical content even if it is on a small detail

[@realdlps]

I'm a game developer myself, not as good as you but I still enjoy making games and releasing them. In my opinion the more technical videos are interesting and I will watch the video asap

[@Dannnneh]

I very much appreciate the technical insight.

[@igz]

Fascinating, and the game is looking great!

[@ludi_64]

Great video! really well explained in an interesting way. I feel like I learnt a lot about how shadows work in video games

[@code-samu]

Hello. First of all, you are making your video in a great and instructive way, I wish you success in your new game (I wish I could solve the logic) :)

[@dbweb.creative]

I think the shimmering is because your PCF averaging square is asymmetrical. Try using Gaussian distribution for sampling. If you don't want to do Gaussian, then you could go with some sort of radial distribution and see what sort of decay you like towards the edges. But yeah.. don't go with a square. You go with a square - you get a square. It's similar to BOKEH in photography, how you can make different out of focus figures by changing the shape of an aperture.

[@dzima-create]

Karl this video was SUPER interesting! Very nice! The game now looks much better. As I heard some time in the past "Lighting is the sound of graphics". And indeed shadows add so much natural feel to the scene!! Actually I also have a video on my channel about shadow programming, but never mind! Good job!

[@ThinMatrix]

Glad you liked it!

[@pedro_mg]

very interesting, I enjoy these more technical ones a lot

[@OCPyrit]

The game looks great, I like the style.

[@ownhaus]

Very interesting. I loved your tutorials and wish you had time to continue them.

[@chillyvanilly6352]

If only professors at universities would explain GFX concepts as well as you do...uff...it would be just a pure joy learning. NOTE: not that there aren't excellent profs out there, just my experience hasn't been all that great so.... Amazing vid, thank you!

[@vast634]

Making the shadows and ambient light darker, and the lid areas brighter would make the game visually pop more. It would appear more sunny in the scene. Currently it looks like on a hazy day.

[@VictorGordan]

Great idea with the bigger area of the shadow map! Also, didn't know about the only rendering back faces trick, always just used an offset :)

[@fueledbycoffee583]

for shadows i would actually recommend a per light source "shadow frustrum" then just clip the camera to it. then you have also automatic shadow LOD