Chris Wallis

Added the ability to watch the rays in my path tracer bounce around as an animation. I'm excited about this more from an education POV, I think it helps explain how path tracing works far more easily than I could describe in words

Iterating on my ray visualizer. Added arrow caps to see ray directionality and UI to tune the ray thickness. I removed the cap on ray count in the bathroom scene and it gets a little crazy. Green = first bounce Yellow = all other bounces Blue = Next event estimation shadow rays

@dev_esnosy Lets me easily specify the thickness of the ray visualization

First prototype of visualizing rays. Fairly simple implementaton: store rays in UAV, then do ray-cylinder intersections in a CS. First bounce is green, second yellow, red for the rest. Shows how dumb my tracer is with very little importance sampling, but it's fun to watch!

@ohnoweknow I used a ray-cylinder intersection from shadertoy.com/view/4lcSRn. Basically I save off all the rays into an array, and then trace against them in a for-loop treating the rays as cylinders with a fixed radius size. It's brute force but good enough for a prototype

@chriskwallis Always dreamt about such feature but were too lazy to implement. Havent understood ray-cylinder part, during visualization stage?

@Jiayin_Cao What is Mano? I'm aware there's ways you could write out strings to a UAV though I worry if stuff like that will either ruin occupancy or drastically extend shader compiler times. I guess I could only light up prints only when I need it for debugging thouvh

@chriskwallis To my knowledge, there are two options to implement it. Mano has a unique way to get it working. UE has an implementation as well.

Put this off for too long, hot reload of shaders. Super useful for debugging, using it here to shut off albedo to see indirect lighting in isolation and then preview UVs. Easy to support since everything is done through a single shader and takes less than a second to recompile.

@Jiayin_Cao Hrmm I don't support shader print yet but maybe that should be next on my list!

@chriskwallis Hot shader compilation coupled with shader print is a must have for debug rendering issues.

Quick and dirty post on implementing hot shader reload with DXC: wallisc.github.io/rendering/2024…

Support for subsurface material editing! I treat glass and subsurface the same. Glass is just subsurface scattering with 0 scattering events.

@vkoskiv @yiningkarlli Yeah I've considered this before, it would be super useful. How big of an effort is something like this? How much do you have to mold your project to fit around Blenders' API?

@chriskwallis @yiningkarlli I hooked mine up to Blender: github.com/vkoskiv/c-ray/… Not the most pleasant experience, many bugs remain, but it’s workable for trying stuff out.

I've avoided making my path tracer an editor for simplicity sake but recently realized how much easier debugging would be with some limited functionality. So here we go, first prototype of material editing

@yiningkarlli Curious to hear what you land on! Retrofitting an editor onto my code is not great, materials are "easy" but just being able to translate a single mesh around in the scene is going to be a PITA..

@chriskwallis I avoided this for a long time too and eventually caved and decided my next-gen hobby renderer will include an editor system. So far I’ve spent a long time building out an editing framework but have yet to actually make much progress on writing the new renderer. 😅

@createthematrix Highly recommend @nico_m__ 's list of graphics folk: x.com/nico_m__/statu…

Oh hey.. just joined the blue butterfly gang under createthematrix. Who’s all there?

@AaronMJacobs3 I'm not going to PAX but I'm in Seattle if you want to get a bite some time!

Been having a lot of fun playing this with my son. The mechanics remind me a lot of the hang glider missions in Pilot Wings but mashed with Kiki's Delivery service

@ThierryCantenot Yeah I do see the CoD and Moana scene having objects being 3-4k units away. I'm not sure I'd establish a unit conversion but I could see scaling a scene so that it always fits within some unit range though. Hasn't been a huge issue...yet anyways

@chriskwallis Well without conversion, an object that is for example 100m away from the origin would be stored as being almost 4000 inches away or 4000 "engine units" in your case

I love seeing studios share real content like this, had to of course drop these into my path tracer and take a few renders. Exposed a few bugs in my code like the banding that I realize only happens with extreme unit scaling

@ThierryCantenot No conversion, my renderer doesnt care about what units the scene is using. My offset is a lot less intelligent, it's just offset by 0.001. I should use that article though! FYI Unreal Engine does use that same trick of shifting the world to camera space for raytracing

@chriskwallis Did you convert from inches to meters? Also what do you use for offsetting rays? I use the code from RTG: link.springer.com/content/pdf/10… For large scale rendering, I was thinking about rendering in camera-centered space (but it would mean updating the TLAS translations every frame...)

@createthematrix Nope I'm using their pbrt variant using github.com/ingowald/pbrt-… which is fantastic. PBRTParser can convert to a "pbf" (binary rather than text based) which takes the load time from 30 minutes to seconds For the Call of Duty USD scene I use Blender to open it and export to gltf

@chriskwallis How are you loading up this scene? As USD? If so can you let me know your process?

Every few months I try and see if I can get the Moana island scene to fit in my path tracer only to give up a few weeks later because it's too damn big. Let's see how far we get this time..

@Jiayin_Cao I'm not sure yet. I haven't even gotten to textures, Im still trying to figure out how to get the meshes to fit!

@chriskwallis Am I right that scene has more than 100 GB memory?