Discovering Fake Caustics in Blender

Let's create a custom procedural texture that can be projected with a simple spot light in Cycles! This can be combined with a simple volumetric shader to get smooth god rays and looong render times.
Monkey project file (free): / 55566549
If you want to support the channel: / polyfjord
Chapters:
00:00 Look at this texture!
00:39 Diving head first into the shading editor
04:24 Copying the material to a spot light
05:22 Something is wrong...
06:12 There we go!
06:30 Adding volumetrics
07:17 The results are in!
08:13 But what about Eevee?
Instagram: instagr.am/pol...
Thanks for watching!
Music:
Purchases made through the links below may provide some compensation to Polyfjord. (This is a great way to support the channel!):
Final result song: shutterstock.7...

[@Ouiigee]

If this "crazy and excited mode" doesn't become a new format I'm gonna be mad.

[@anonymus3264]

I love how the cassette-label says: should have used cycles X for this vol. I xD. Anyway this is a really great tutorial which i am sure will help many people (me included) a lot

[@craftmasters7497]

Oh my god i didn't even know cycles x existed until now soo cool.

[@johnclemennbugcat1915]

This is just so beautiful. The way that you're trying to speed everything up makes it feel like this is a scientific discovery happening in front our eyes.

[@aaronrothwell7615]

If you can't see the "Use nodes" on the light, make sure you have Cycles set as your renderer.

[@drgz871]

tyyyyyyyyyyyyy sooooo much

[@8161chris]

@@drgz871 Thanks! Was looking everywhere for that!

[@lasseoverath7858]

thanks, but if i do this my pc is gonna go brrrrrrrr boooom

[@vedaanshcairae]

the comment we need!

[@user-wf2oh8ws5l]

Thx so much!!!!!!!! I was confused that stage!!!!!

[@gurukn]

Is there anyone here that doesn't let their jaws drop while watching these videos? imo, a major part of the reason for that is the amazing way you explain this. You're just stunning, m'dude!

[@textellerdude5768]

Ikr. Looked like that movie scene where some professor fascinated of a breakthrough observation.

[@paindavoine_design]

Thanks for sharing ! 4D Voronoi is very demanding for the computer, I used 3D Voronoi instead, the Z axis being used for the evolution instead of W. This way, I can use it directly on the mesh itself to make a swimming pool, and it's very fast (24 fps, real time). For a better effect, you can overlay two of your Voronoi modules with a slightly different mapping.

[@guitoo1918]

In some video games, it's done with 2 tillable voronois bitmap that are multiplied together and thresholded. Each one move in a different direction. I think it was in a GDC video but i couldn't find it.

[@JordanMossy]

@@guitoo1918 you are correct, it's a technique that's been done for years in gamedev. Majority of effects in games are combinations and differences of noises with different panners, fire, lava, slime all can be done with that technique.

[@Florianski]

This is such a lifesaver! It literally halfed my rendertime whilst looking just as good!

[@millhim7523]

I love tutorials like this. It just goes to show the creative spark can literally happen at anytime, even as soon as you’re about to get off. Also that effect is super clean, well done.

[@arnavmaharshi9280]

Oh man, I have wanted to create this effect for such a long time, thank you so much for making this!!

[@julzius6796]

"this is going to take a while to render" proceeds to render out 3 generous animations showcasing the effect

[@somehowrl7307]

This is nuts. Just found your channel recently and subscribed as soon as I saw the first few videos I clicked on. This has to be one of my favourite effect videos anyone has put out about blender so far! The excitement, the ingenuity and best of all the "I cant go to sleep without making this tutorial": perfect!

[@Polyfjord]

Haha!! Thanks for watching, my friend!

[@TomWDW1]

What - The - F ..... This is AMAZING! I've been doing Blender for a year now, watched so many hours of tutorials and have never seen anything like it. Thank you so much!!

[@ParkerWinters]

I just discovered your content TODAY (thanks to Andrew Price), and I am blown away. For each video of yours that I've seen so far, I find myself wishing I could give it a thousand likes. Your production quality is amazing: the thought you put into the animations and textures, your sound design, your explanations of things, ugh. It's all so great. I sincerely hope I get to watch your content for years to come. Your passion for this art form shines through in every video, and I love it. Keep up the stellar work.

[@beses4530]

I LOVED this format, your enthusiasm makes it much more interesting

[@heckensteiner4713]

My grandpa always said, "If you want to fake caustics, use a Voronoi texture." Wise words. Rest in peace grandpa!

[@guns1inger]

"It renders so slowly" while producing 333 full HD frames in under 90 minutes. I used to wait 24 hours for a single 800x600 frame using the Ghost (later Brazil) renderer. This is practically real time in comparison. Nice work

[@Polyfjord]

Hehe... That’s crazy to hear!! Maybe in 10 years, we’ll all be nostalgic about waiting for renders to be done, since everything is real time. Thanks for the perspective, my friend!

[@BlenderVision]

@@Polyfjord I hope so xD

[@arturcorreia8465]

I loved how casual the whole tutorial is.

[@kyronking2975]

i needed this so bad , thank you Jordi

[@stuffystuff1661]

you can also use a similar node set up but on the volume itself to control the emission input (put the density on 0), you might also want to set up the textures as 2Ds. this way you get godrays without sacrificing speed.

[@stuffystuff1661]

I just tested this idea and it works like a charm

[@syborg64]

To increase performance you should definitely use a 3D version of the voronoi and animate it on the Z. The advantage of 4D with W is that your could also make it loop with a sine cosine pair. Alternative way to do it for eevee would be to use that procedual texture on the object's material with the lamp's coordinates, and multiply it with diffuse->ShaderToRGB.

[@beautyislikeyeah]

Forgive me if this is a massively stupid question but I don't see a place to connect to the Z axis in the node editor in the same way that switching the Voronoi texture to 4d reveals a "W" value to change. Can you point me in the right direction of what you mean by "animate it on the Z"?

[@syborg64]

@@beautyislikeyeah There is a node "Combine XYZ" (Add->Converter->Combine XYZ" that lets you set independently each part of the vector. This gets you a purple socket you can connect into the voronoi input. You could then also add a "Seperate XYZ" on your original input coordinates and connect X and Y to the Combine, then set Z to your keyframed value. The reason 4D textures let you specify W independently is because blender's vectors are exclusively 3D. whereas actual mathematical vectors have arbitrary size

[@beautyislikeyeah]

@@syborg64 Thank you so much for this. Hadn't run across that node before and it sounds super useful. Can't tell you how much I appreciate the reply. :)

[@dukevera4216]

man, I would love to do this! How do i make a sine cosine pair? please!

[@syborg64]

@@dukevera4216 the process is simple: bending spacetime curvature onto a 4d hypertorus all joking aside, start with an input node and animate it to linearly go from 0 to 1 in the time you want. (here, either match animation length to let it autoloop or actually keyframe it to any whole number and use a modulo by 1 (math node) to bring it down to the 0-1 range) Multiply your input by 2*pi, to get it to a range that loops with trig functions Connect it to 2 nodes (in parallel) : sine and cosine (math node) Seperate your input XYZ vector, keep only the XY, Combine inputX, inputY, sine into a vector (combineXYZ) feed the combineXYZ and second trig function node (as W) into your procedural texture. if you want to change the apparent speed of the animation, multiply the output of both Sine and Cosine by the same value Voila

[@yashs2756]

Thankyou for showing the part where you get stuck, none shows it, we all know it ahppens to everyone, so you showing that part may help anyone understand how to think when you get stuck.. Your channel is fucking amazing

[@g_niac]

perpetually in awe of how talented 3D artists are. so cool being able to watch this and almost be able to keep up in real time lol. still have to go back but stoked i can be like excited when mapping and coordinate nodes make way into tutorials. def felt the mad scientist vibe on this one. dig it. thank you.

[@ThemisadventuresofLu]

Stunning! So pleased that you shared this with us! Thank you so much, cant wait to try it out for myself

[@currenluna]

The examples at the end are unreal! This effect looks great.

[@AndrewConway]

Over the Top!... In my four years of playing with Blender, this is in my Top-Ten Tutorials I've come across... A debt of gratitude is owed to you.

[@RSpudieD]

WOAH!!! Dude that's awesome! It looks so cool and I don't blame you for being so excited that you jus had to make a video at all! I wasn't sure where this was going but when it's animated it really looks amazing and underwater-like! Nicely done!

[@krizalide1]

I really like how you explain and teach how to do relatively basics things, but at the end show examples of what it can do if you push it further. It's sometimes hard as a beginner to visualize where it could go if we spent more time on something, so it's very helpful.

[@sirchewtrain]

I love your “crazy” this is god tier content.

[@ClintMoody]

This channel is in my top 3 favorite Blender channels. I say Top 3 because I couldn’t pick just one favorite. The render info in the bottom left of the renders is just… *chef’s kiss*

[@axxl4750]

- - - 4.0 Fix - - - Connect the mappings vector to UV instead of normal in the texture cordinates (i set my mapping scale to 0.7) so i can see the caustics a bit better **I personally dont recommend linking scale and randomness but that is up to you*** for the RGB mix Shader Replace the Difference to Lighten (in the Rgb shader modes you can get different styles that go well with caustics too, i just chose lighten because it went well with the project im working on) play around with the color ramp that links the Lighten to the Light output (this only works on Cycles) Hope it helps! :)

[@peroxideman5292]

I have absolutely no Idea why this was recommended or what is going on, that being said I watched every second as excited as you were making the video. Kinda like when dogs get super hype just cause everyone else is happy

[@aymanehammi]

You can create you own crazy textures or effects for your next project , tanks man , i love your tutorials , keep going

[@florianbusch3082]

Man so glad I found your channel. Not only your tutorials are great, but your examples and renders are actually not looking like garbage but instead highly artistic and contemporary like it’s actually usable on anything with a modern approach. Wow!

[@samoulton8308]

It’s infectious how quietly excited you get about new discoveries. Excellent presentation and pace.

[@garycartwright4269]

Posted on September 1st, my birthday. Outstanding in both respects. Well done Polyfjord, you never cease to amaze me....

[@jaredharper205]

The applications for under-water scenery and shorts is so clear, what a wonderful technique!

[@fish3170]

I was thinking about it since seeing Curtis Holt's Light Nodes video. Thanks for showing us!

[@Polyfjord]

Cool!! Will check it out! Thanks!!

[@NeatWolf]

It's the first the video from your channel that I'm watching and I'm dropping a comment just to say I'm so fascinated by your enthusiasm. I really miss working with people so motivated and passionate. Keep up the great work, never lose the passion

[@NeatWolf]

You know what you could have added? I haven't done a lot of research but the colours split at some point, so you may want to add a bit of something like chroma aberration to make it even more realistic. I guess :P

[@marcfuchs6938]

Watching this and solely working with Eevee, I was like "using this as a texture and adding transparency, this should be no problem in Eevee" - when the after-credits scene showed just that. =) Absolutely great stuff, I'll use this in the future and I am sure, the shadow issues can be sorted out at some point. Afterall, the shadow should exactly be, what the texture offers.

[@michael5985]

So happy to see your new video!

[@CapitalGearGaming]

5:22 is such a relatable moment, even the let's increase this number... Okay nothing? Let's increase that number by like 20 times.... Hmmm...

[@neotower420]

whoah, this is thinking outside the box!

[@HowieTung]

I am always fascinated by the reflection of the light from the water, it's just so beautiful.

[@AzuriteBox]

Looks so much like water love it!

[@monotoshdey190]

you are able to make the most simplest things in blender so much more cinematic it blows my mind. my god bless you dude and thanks for the tutorial

[@adnanerochdi6982]

aside from everything, the touch of chromatic aberration on the caustics in the renders, was such a smart attention to detail that helped the effect tremendously! great tut

[@KonJonnorMusic]

The underwater Walkman was one of the most impressive things I've ever seen in animation. Learning so much from you, Polyfjord thanks so much !

[@runforitman]

it looks like light shining through water very pretty

[@Mark_Alloway]

Very nice discovery. Loved your enthusiasm

[@Heavenira]

It looks more like a Voronoi texture than actual caustics. That being said, for a fake method, it works pretty good.

[@sIavoo]

Oh man Your excitement here is amazing. Absolutely love the video and results!

[@calumcooke1155]

That sony walkman shot was awesome!

[@Adem92Foster]

Wow, this looks amazing I feel like earlier versions of the node group could even be used to make environment spiderwebs with all the different contrast levels to fake the thickness

[@Polyfjord]

Ooooh nice!! Yes! I love it!! Have you tried it?

[@Adem92Foster]

@@Polyfjord Not yet unfortunately, I just watched this video on the way home from work ahah, I may try tomorrow Great content :)

[@neelkaklotar2710]

The example you show is another level render 🤯 love your videos

[@Ritticle]

I will never make these things but It's so satisfying watching you create this image you have in your head and be so eager to share it with everyone else. Beautiful.

[@yerwol]

Love the late night tutorial! Amazing stuff!

[@Polyfjord]

Thanks so much man!! I was afraid it would be boring compared to the more heavily edited stuff I've posted lately. This video was so much fun to make!!

[@tyler961]

Wow this was mind blowing to watch

[@ifroxxx1226]

7:40 holy cow that is incredible.

[@aarrkkee]

I honestly don't care about 3D modelling at all, but seeing someone this enthusiastic and excited about something, really does make the video enjoyable anyway.

[@3dpeterartmileo296]

Gladly I could make this exercice too and actually applying in my stuffs. tks

[@xvirei]

Ah i just discovered your channel and I feel like crying, you are explaining everything very clearly but its also very fast? I really cane across a miracle thank you so much for tutorials! It really changes the quality when someone is passionate about the subject

[@TonjuwelenDeAgentur]

Out of control! Great work. Thanks so much for sharing.

[@bos3d246]

Best notification from youtube Trust me, your videos are amazing😍😍

[@mrksthl]

Super Awesome! Thanks for the video!

[@Unearthlywhales]

Very very cool! Thanks for sharing!

[@johnabruzzi5148]

This tutorials are so satisfying because he is a pro. Thanks and keep doing this Videos.

[@SophiaRSK13]

Amazing! Thank you for sharing!

[@DerekElliott]

great technique -- I tried something similar in eevee but with the caustics being the actual texture on the object. Your method seems way easier, will have to try!

[@Polyfjord]

Hey Derek, great to see you here!! Interesting. It would be really nice with an easy way to do this in eevee! Like the texture data is already there in the node, should be possible to just slap it on there somehow

[@leatherworkstation]

Wow! Didn't even think about using nodes on lights to project more interesting things. Heads full of ideas now.

[@JokerLover123]

Finally someone who know when to get the facecam out of the way.

[@Derio]

You sick bro! In a good way, thanks for sharing!

[@unhelpful-harry]

it's hard to decide which is more impressive: the creative capabilities of 3d ray tracing software, or the community of folks like yourself sharing their research therein. this is so cool and helping a lot with an indoor scene im making that involves water. thanks mate, subscribed B)

[@Polyfjord]

Thank you my friend!! Hope you’re excited for the next version of blender, where we get real caustics!!! Will be very cool!!

[@whynotanyting]

Had a strange dream that I wanted to recreate and caustics were integral to the lighting. Much appreciated!

[@JonasHassibi]

this is sooo good, thanks for sharing man

[@_us-studio]

You can get sharper shadows in eevee by bringing the size value of the light really low (Eevee calculates shadows of a light with a size > 0 by essentially wiggling the point source around which is why shadows aren't amazing), and bringing the plane closer to the scene rather than the light source. You can also turn off 'soft shadows' in the render section.

[@user-tb6ch1qq5b]

Thank you. Will try it tomorrow

[@venessamay3433]

Love this so much. Gonna try this one

[@tzurgvili9987]

You really need to join the Coridor satisfying video competition

[@anjajerala8617]

*Exactly* what i have been looking for for years! Thank you so much, it's an awsome tutorial (all of them are really :) )!

[@kurtdewittphoto]

So awesome. Caustics are one of my favorite things to look at.

[@JohnFranklin1982]

Wow! That is terrific! Thank you for immediately tapping it to show us! Thanks very much! I can use this very well in my projects!

[@Polyfjord]

Nice!! Looking forward to see what you’ll create! Feel free to use #polyfjord on instagram!

[@7evYT]

I wish I could be this passionate and excited about something.

[@Dantti]

Glad you made this, thanks man! 🥰

[@toddspeck9415]

Wow! Watching you use Blender is wild. I have been studying and learning crazy cool things from your spider with glass legs tutorial. Thank you so much.

[@SagarCubes]

7:52 "Should have used Cycles X for this" lol hell yes

[@DrBread-zr3fv]

I love the tutorials you're making, I'm new to Blender and they've been helping a lot

[@ximm2mhd.zakyrionaldy187]

I still confuse how you figure out the easy way of doing something, great work man 👍🏼

[@JayJamBAM]

lol damn love the excitement and fluidity

[@MrHummerle]

gorgeous! thanks for sharing!

[@animeotaku5297]

I loved this random tutorial of yours... Thank you sensei ♥️

[@Domzdream]

It’s exactly what I need for my work I’m doing right now. Thank you x a 100000000

[@itsme_thegamer]

as soon as i saw your video on the home page i clicked really fast to learn something new

[@sabinn.learning]

he comes late but comes with strong content.

[@lauradominguez379]

yes you look like a crazy person in the dark but here I am looking the same way haha thank you so much!! this one was reeaally helpful :)

[@notimportant7682]

great effect, I found easing the mixRGB node to about 80% produced a more natural look, and not letting the dark areas be 100% shadow also helps sell the effect

[@martinwidmann6714]

My god! This is amazing!!

[@judofernando8298]

been looking this for a long time.. thank you so much ^^

[@True-VFX]

If you use the shadow ray node and use that to drive a transparency shader mixed with glass (or a custom water shader) using an inverted normal value, the you can make your object cast caustics as it’s “shadow” too. Good for faking caustics in glass or water… happy to share our shader with you to reverse engineer and post a tutorial for others to learn how to do it.

[@Ajee02]

Honestly the best part about this tutorial is the bit at the end where you set the background to a volume scatter

[@c4x387]

What!?! That last render with the cassette is insane! Looks real!!! You have to do a tutorial on something like that! The debris in the water and the movement looks perfect!!!

[@tobinloveday]

This is awesome, keep up the great tutorials and keep discovering!