The floor also needed some bounce lighting
'Could somebody with no programming experience recreate Photoshop with an LLM?'
I have absolutely zero Metal and near-zero 3D modeling experience. I know the basics of how to use a scene editor, and the names of rendering terms.
And I effectively vibecoded all of this in less than half a day with Codex 5.3 Medium, based on screenshots of a cool-looking app I've never used (Valence3D) and just a general sense of what a 3D app should do
Raytracing uses every last ounce of my poor M1 Mac mini's GPU. It has never seen such a workout
Since I am doing this on the GPU, not CPU, finding a way to render complex meshes without blowing the budget is a headache. There's a hard cap on how much work you can do before the Metal driver crashes
I think I should probably add a denoiser to this…
Added some targeted calls to the hardware raytracing APIs, and a toggle switch so I can flip between non-accelerated RT and accelerated RT. There are plenty of bottlenecks in my renderer to stop it taking /full/ advantage of acceleration, but holy heck it’s much faster regardless. This is on the M5 iPad Pro
Turns out the M1 supports enough of the hardware accelerated raytracing APIs that I get a massive speedup here, too?
Trying to parse Apple's Metal feature support tables is hurting my brain, so I'll just accept it and move on
I can almost render this dragon mesh now before the GPU gives up 🐉
Submeshes and MTL texture loading
I think I'm just making Bryce now? That's a thing
Procedural water to the horizon, sky, island generation
Not me offloading raytracing workloads to my iPad because it's so much faster than my Mac…
I spent untold hours in Bryce3D as a kid making silly scenes just like this. It did this stuff with machines a thousand times less powerful than my Mac mini. Certainly puts things into perspective…
It's real nice having a complex app like this on iPad, that's for sure. This is by far the most complex and impressive thing I've vibecoded with Codex 5.3. I haven't seen or touched a single line of code, I didn't have a detailed plan to work from — this isn't at all like the structured ports I detailed previously
I thought my water should have some translucency and falloff, so I can put things underneath it
Procedural clouds seemed like a good idea
Recap: I vibecoded (code unseen, no plan) a 3D editor/renderer that has a scene graph, editing controls, primitives and gizmos, materials, procedural terrain and water, and hardware-accelerated Metal raytracing with soft shadows, clouds and bounce lighting, that runs on Mac and iPad.
Tool: Codex 5.3 Medium
Time: About a day's worth of work has gone into it
I figured I needed some kind of glass shader
The thing about material shaders is I don't quite know the right questions to ask — the unknown unknowns. Am I taking into account the right refraction, internal reflection, attenuated shadows, etc. Why is this too bright, why is this too dark. You can tell from these examples where things are obviously wrong, and it takes quite a bit of iteration
'Attenuated shadows'
A little better
Maybe I should have bought a faster Mac before trying to write a raytracer…
Trying not to fry my GPU with caustics, but Metal isn't happy
I was sitting through hour-long renders (!) on my iPad yesterday, so I did an optimization pass on the hardware acceleration and it's much, much improved for simpler scenes, even on an M1
While this raytracer may never become a finished app, there are certainly elements from it I intend to yoink for future projects — like the really neat toolbars that go around all the screen edges, they would fit into a complex pro app very nicely
Just casually building and raytracing a scene on an iPad mini 6, nbd
Of course it runs on iPhone, what do you take me for?
So, like, what do I even do with this app?
I made my control groups collapsible, with a priority system. Honestly they're my favorite part of this prototype
The old viewport gizmo was faked in 2D, so I had it rewrite it in Metal and with a different projection, and now it's much better. I also added exponential decay to the orbit gesture so you can fling the camera around
Ha, cute, you can even fling the raytracer around 🤣
Also I added an expanded progress indicator
Hadn't tried the visionOS build, but it works too.
With a caveat.
visionOS is far more fragile to anything like 3D rendering. Saturating the GPU like this slows the compositor to a slideshow, and even got to a point where Metal was leaking out of the window into the OS and I was seeing squares of corrupted video memory in front of me until I got the equivalent to a SpringBoard crash.
Functionally, this could be a visionOS app.
Practically, no.
You can see here that the moment I invoke the raytracer, everything goes to shit on visionOS. The userspace went down right at the end of the video, where it cut
What if you could step into your Bryce scenes?
Pretty much everything I've worked on with Codex up to now has been stuff I could have built myself, within my area of expertise (or learnable), it just would have taken weeks or months.
This 3D scene app is something I never would have been able to build myself. I would have needed a team of rendering experts with domain-specific knowledge and human-years of research
@stroughtonsmith your results are amazing, but got me curious about Codex writing Metal, so I asked it to make a solar system simulation
After two hours of back-and-forth it still can't seem to texture a sphere in a way that doesn't cause the lighting and texture to rotate with the view
I gave it six goes at trying to get the bloom effect correct, but in the end had to paste an entire blog post into its context about how to render bloom in Metal
The conclusion to this story (cc @stroughtonsmith)
I stepped away for a couple days and it hit me that what I was seeing really looked like the planets were inverted (their back-faces were being rendered, so I was seeing the "insides")
I reported this to Codex, which told me, "Good hypothesis, but likely no"
I asked it to add a culling option. It absolutely was rendering back-faces the entire time 🤦
@simsaens omg.
I have had the same thing a dozen times with things I'm doing in my renderer. It's just more obvious with non-spherical meshes
Steve Troughton-Smith
Sim
