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Show HN: A physically-based GPU ray tracer written in Julia

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Show HN: A physically-based GPU ray tracer written in Julia

#1

Post by simondanisch »

We ported pbrt-v4 to Julia and built it into a Makie backend. Any Makie plot can now be rendered with physically-based path tracing.

Julia compiles user-defined physics directly into GPU kernels, so anyone can extend the ray tracer with new materials and media - a black hole with gravitational lensing is ~200 lines of Julia.

Runs on AMD, NVIDIA, and CPU via KernelAbstractions.jl, with Metal coming soon.

Demo scenes: github.com/SimonDanisch/RayDemo

Show HN: A physically-based GPU ray tracer written in Julia
makie.org

Re: Show HN: A physically-based GPU ray tracer written in Julia

#3

Post by amelius »

Is the material description part of the language the same as in PBRT?

I'm asking because I had a lot of trouble trying to describe interfaces between materials, only to find out that what I wanted to do was not possible in PBRT without modifying the code. Apparently, in PBRT a material can only have one other material touching it. So, for example rendering a glass filled with water and ice is not possible without hacks. From a user's point of view this is a bit of a let-down, of course.

Context: https://news.ycombinator.com/item?id=45668543

Re: Show HN: A physically-based GPU ray tracer written in Julia

#5

Post by simondanisch »

amelius wrote: post #3

Is the material description part of the language the same as in PBRT? I'm asking because I had a lot of trouble trying to describe interfaces between materials, only to find out that what I wanted to do was not possible in PBRT without modifying the code. Apparently, in PBRT a material can only have one other material touching it. So, for example rendering a glass filled with water and ice is not possible without hac…

Nope, we made a complete high level Julia interface and I plan to have the Makie API be the main user facing scene description, which can be more descriptive than pbrt I think!

Re: Show HN: A physically-based GPU ray tracer written in Julia

#6

Post by simondanisch »

LoganDark wrote: post #2

On iOS Safari the videos are fullscreening themselves as I scroll. I've seen this on other blogs before but I don't know what causes it. Super annoying

Ugh, yeah I had some super weird bugs like this in safari, still haven't found the source :(

Re: Show HN: A physically-based GPU ray tracer written in Julia

#7

Post by amelius »

simondanisch wrote: post #5
amelius wrote: post #3

Is the material description part of the language the same as in PBRT? I'm asking because I had a lot of trouble trying to describe interfaces between materials, only to find out that what I wanted to do was not possible in PBRT without modifying the code. Apparently, in PBRT a material can only have one other material touching it. So, for example rendering a glass filled with water and ice is not possible without hac…

Nope, we made a complete high level Julia interface and I plan to have the Makie API be the main user facing scene description, which can be more descriptive than pbrt I think!

Ok. Did you see this:

https://blog.yiningkarlli.com/2019/05/nested-dielectrics.htm...

And I'm curious how you solve it.

Re: Show HN: A physically-based GPU ray tracer written in Julia

#9

Post by simondanisch »

krastanov wrote: post #4

As an aside, it is really interesting to see a computational package that, while supporting multiple GPU vendors, was first vetted on AMD, not NVidia. It is encouraging to see ROCM finally shaking off its reputation for poor support.

well, I do hate vendor lock in with a passion ;) But yeah, a lot did happen, this likely wouldn't have been possible one or two years ago!
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