Unreal 5.3 - Making a volumetric ray marching shader from scratch (part 1)

In this new video series we will create a volumetric ray marching shader completely from scratch, including a pseudo volume texture editor that we can use in-engine.
Some notes:
- This is based on a tutorial series made by Ryan Brucks, Principal Technical Artist at Epic Games. Check out his blog at shaderbits.com/
- The volumetrics plugin has a pseudo volume raymarcher (also made by Ryan), but the VolumeBoxIntersect function doesn't work properly in Unreal 5.3.1, which causes graphical errors. This video shows how to fix the problem with the function's code.
Texture used in the video: www.dropbox.com/s/9h98z1mlhp1...

[@christopherstrawley7024]

Thank you for sharing these lessons Enrique! The videos you release always somehow line up with what I'm curious about learning in the engine and I could not be more grateful for your perspective and experience in these topics! Thanks so much!

[@isaackershnerART]

This Tutorial is amazing! Ive wanted to do something like this for a long time now but never had the will to delve into hlsl and raymarching. You gave me everything I needed to get started and then some!

[@EnriqueVenturaGames]

Glad to have helped get you started! Good luck and thanks for the comment!

[@Cz_Dani]

This is a goldmine for me! Thank you for teaching some really deep topics, volume rendering in unreal was always a scary thing for me that seemed too complex for me as an artist but you really break it to a logical explanation.

[@EnriqueVenturaGames]

Thank you for the kind comment! :)

[@AboutJOB-dq6pj]

Nice video!! Thank you for the sharing this!!

[@matiasadrianmahler322]

This is insanely usefull Enrique, muchas gracias!!! Disabling the depth test means it will be calculated and rendered even when occluded? Or does the distance used to multiply the steps does that optimization by reducing the render calculations when occluded?🤔

[@ooorc46]

Love you! Great topic!

[@sergiogonzalez2611]

WONDERFULL TUTORIAL MAN, JUST WONDERFULL

[@EnriqueVenturaGames]

Thank you kindly!

[@elgabacho73]

Muy buenos tutoriales. Saludos!

[@EnriqueVenturaGames]

Muchas gracias! Saludos de vuelta! :)

[@skydek]

Buenísimo ¡muchas gracias! tenia artefactos con lo del depth testing al intentar implementar el shader de Ryan Brucks, este tuto me lo ha arreglado :) Ahora a ver si encuentro forma de escalar las mallas de manera no uniforme, que por ahora se rompe la profundidad

[@EnriqueVenturaGames]

Ayer estuve un ratillo intentando solucionar el escalado no uniforme y no lo consegui del todo, si das con una solucion sencilla avisa! :D

[@skydek]

​@@EnriqueVenturaGames por lo que he estado probando parece que al hacer la solucion para evitar los errores de depth testing se rompe, es decir, con lo que viene por defecto el plugin de volumetrics en la funcion de VolumeBoxIntersect parece que funciona bien el escalado no uniforme. Ahora bien, no se como, pero he vuelto a lo por defecto y he visto que no tengo el mismo error que pasa en el tutorial antes de hacer el fix; la profundidad funciona correctamente ya de base asi que no estoy seguro si al final este fix del VolumeBoxIntersect es necesario ( aunque no estoy en la 5.3 sino en la 5.1, puede ser que algo haya cambiado) Seguire mirando a ver...

[@Froothy]

i dont get exactly how it works but it does and i like it

[@Labo3D]

Amazing! After a little bit of extra work i decided to integrate the shadows too , was wondering, do you think it would possible to take in consideration the the non uniform scale of the mesh? As for now if the mesh is not scaled accordingly, it seems it's getting distance faded out on Z axis

[@EnriqueVenturaGames]

Yeah I'll look into it for the next video :)

[@Labo3D]

@@EnriqueVenturaGames you're magic ✨

[@Labo3D]

@@EnriqueVenturaGames Just wondering, do you have a good tutorial or course to learn HLSL? I can like revise a lil bit HSLS code (as i did with this project), but i'm not super fond with starting from scratch.

[@EnriqueVenturaGames]

@@Labo3D sadly I don't (yet); I've been thinking about doing a series of videos for complete beginners (HLSL, niagara, materials, etc.) but I've been too busy with work and life :)

[@Labo3D]

@@EnriqueVenturaGames I totally understand ahah, takes a lot of time to prepare tutorials ^_^ Thanks a lot :)

[@haikeye1425]

Nice!

[@JesfNwje]

Any chance you could make a volumetric sphere cloud using materials?

[@Stryper1456]

Really great stuff! Thanks for sharing! :) some help if I may? When I hook up the MF_VolumeBoxIntersect into the main shader, I can't see my cloud anymore, even though my Tex Object is hooked up. I end up seeing the box volume itself, as soon as I hook up the BoundingBoxBased UVWs, I can see the cloud once more. I don't have volumetrics enabled in this project, I did however copy and paste the MF from another project and remade it myself. All seems to compile, so I'm unsure where the error has come from :(

[@EnriqueVenturaGames]

The VolumeBox Intersect function has some errors in the current version (or at least, something in the LWC system has changed so it doesn't work now). I mention it in the video, including a temporary workaround, not sure if you have done that modification and still have the error.

[@Stryper1456]

Ahh maybe it's further along in the video as I haven't encountered you saying that yet, or possibly I missed it, and if so I apologise. Really appreciate the rapid response by the way@@EnriqueVenturaGames

[@Stryper1456]

Yeah the fix resolved it! 👍Really great content & Support. @@EnriqueVenturaGames

[@fran.fndz.techart]

this is great, i finish the shadow and lighting also, but im having trouble adding animation, i have added distortion effect to the volume but i want to rotate it, rotating the float3x3 WtoL = (float3x3)LWCToFloat(GetPrimitiveData(Parameters).WorldToLocal); in the Z axis does not work properly, but if i rotate the mesh in the editor it works with no issue. if u have spare time, can u try to rotate the mesh and the volume inside the material?

[@EnriqueVenturaGames]

Sure, I'll give it a try!

[@EnriqueVenturaGames]

Working on part 3, I'll do an entire section on animation because there are multiple options :)

[@fran.fndz.techart]

@@EnriqueVenturaGames glad to read that. I had some issues with animation so I jumped to volume fog / vdb

[@hotsauce7124]

Question, How would we render these clouds with an alpha background so they can be composited?

[@EnriqueVenturaGames]

Haven't tried doing compositing using these yet, but in a worst case scenario you should be able to make a copy of the material that only outputs transmittance, and use that as the compositing mask. I'll look into it for a future video!

[@hotsauce7124]

That would be an AMAZING future video. Thank you! @@EnriqueVenturaGames

[@EnjoyLife-233]

I'm sorry I can only use software to translate the reply. Thanks for sharing, and I had some problems reproducing the project. When I hook up Color (purple) into the Emissive Color, there will be a light-purple-translucency cube outside the cloud. Then I used Color (purple) multiply Custom return accumdens, and content to Emissive Color, the cloud display is correct. I'm confused about that.

[@EnriqueVenturaGames]

If you just connect the color to the emissive output, the whole mesh (the cube) gets the color applied to it. By multiplying it by the accumulated density, you are only tinting the actual cloud, because the area outside of it has a value of 0 (accumdens)

[@ashishthatipelli3279]

Can I disable the lightning in these volumes?

[@daylight3d]

Nice tutorial. But it would have helpe to paste the code into the video description to copy & paste. I am not a coder and have to check 10 times that every character is in its right place.

[@lapotk.3150]

❤

[@SilverEye91]

You mention the limitations of the volumetrics in the engine, however, do you need volumetrics activated for this to work anyway?

[@EnriqueVenturaGames]

I don't think you need the plugin activated to follow this tutorial. Good luck! :D

[@SilverEye91]

@@EnriqueVenturaGames Thanks! I have some limitations for this project, unfortunately I'm also limited to UE4. I'll probably run into some issues because of that but hopefully I will learn some things. If nothing else for use in future projects with a more modern version :D

[@importon]

Is the only geometric shape that contains it a cube? meaning, can I "fill" an object with this material? Basically I'm looking for a way to fill and arbitrary shaped object with smoke.

[@EnriqueVenturaGames]

Since volumetric raymarchers work in voxel grids, you still need to start with a cube (of voxels). To "fill an object with clouds", you would need to sample the mesh's surface and then use that information to generate a volume texture, but the texture would still be rasterized using a cube mesh.

[@lapotk.3150]

🎉

[@Curryfishballa]

I've got error on the PseudoVolumeTexture function where the TexSampler is unidentified. Any idea how you it worked for you and not me?

[@EnriqueVenturaGames]

That is a quirk of the custom node in Unreal. If your texture is not named "Tex", the default "TexSampler" won't work (and you get that "undefined" error). Depending on your Unreal version, you might be able to get it working with Tex.Sampler, but the easiest solution is just to make sure that your input texture is named "Tex"

[@Curryfishballa]

@@EnriqueVenturaGamesomg!! Thank you Enrique, your tutorials are amazing! I can continue with the tutorial now! Also, your technical art related tutorials on youtube are really something. I’ve learn so much from you with so less!

[@EnriqueVenturaGames]

@@Curryfishballa Hey thank you for the kind comments! Feel free to ask questions anytime!

[@dusha3030]

I can't manage to get the sampler even though my texture name is Tex. I tried both TexSampler and Tex.Sampler in UnrealEngine 5.3.

[@selenepark40]

in my case, I used TextureSampler node for Vol_texture, instead of TextureObject node. You may check that part too :)