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Frenetic Pony

Member Since 30 Oct 2011
Offline Last Active Today, 12:25 AM

Posts I've Made

In Topic: Is OpenCL slowly dying?

24 September 2016 - 10:33 PM

I'm curious what leads you to believe that support for OpenCL is waning. From what I can figure, most graphics developers didn't care for CL much due to clumsy interop with GL, which is why compute was added directly to GL core in 4.5. It's much more useful to game/graphics developers in that format than CL is, and CL has moved to more scientific computing type uses. I don't think Vulkan plays in at all.

 

Yah, I've only seen OpenCL and the like used for simulation/neural network/etc. stuff. Graphics tend to stick with whatever's native as possible.


In Topic: Bug: Overly Sharp Highlights in PBR

06 September 2016 - 06:46 PM

Some more information would be helpful, specifically: What is it that you are trying to accomplish that is not being accomplished? A comparison image of the reference/target render as compared to your results for example.

 

Just looking at the provided picture doesn't make it clear, I see 5 apparently shiny materials that I would assume are correctly being rendered as shiny, and a rough brick material that looks fairly rough. So right now no error appears obvious.


In Topic: Horizon:zero Dawn Cloud System

23 August 2016 - 03:37 PM

 

recently  i read the gpu pro 7 article <>, i want to implement a volumetric cloud system myself.
Recently I read you thread, and it really made me want to implement a volumetric cloud system myself! :D 

 

This is running at 0.2fps, using brute-force code (no textures). Now I have to optimize it using all the knowledge in this thread. Thanks for the inspiration!

clouds.png

 

 

Well it certainly looks pretty, so that goal is accomplished! And by all means, grab DICE's take on this stuff here: http://blog.selfshadow.com/publications/s2016-shading-course/

 

Nothing dramatically changed, but some nice findings none the less.

 

Edit- Also, thinking about this, Naughty Dog had a nice hack with Uncharted called "mip fog". Which was just the skydome mip-mapped and applied as a kind of "fog texture" lerping between high mips for distant objects to low res for closer objects. It's a hacky way to do scattering and get your "fog" to seemlessly blending into your sky, and I'm sure you could come up with a way to do custom mips that hews closer to physical scattering.

 

But with volumetric clouds you need a way for close in scattering (below the cloud layers) to match the scattering from indirect light, which would be dominated by the skydome outdoors. So you could do the same thing here, grab a progressive/time sliced cubemap of the skydome (X by X pixel tiles per frame, lerp between previous tile to new tile over time to avoid worst artefacts at tile edges?) and then you could mip the skydome cubemap easy enough to do the same thing.


In Topic: Theory of PBR lighting model[and maths too]

13 August 2016 - 06:00 PM

 

I am familiar with these ideas, though they are high school physics topics, lets test my nostalgia  :)

 

A. Applicable only for mirror like surface. For rough surface, the angle of incident and the angle of reflection will not be same, is it?

 

It is actually, part of the laws of reflection :P. But due to visual reasons, we approximate micro-faucets. Which is why a probability distribution function is introduced. It represents the probability of running into a microfaucet along a given surface. So physically, the angle of reflection is always equal to the angle of incident across the representative normal. But we bend this rule to get a result that's more to life with limited data.

 

But yeah, that book is aligned for giving you concepts of physically based rendering for things like pixar's renderman. It won't help you to implement anything to the GPU.

To do that, you'd want to take a preexisting BRDF. I'm trying to use Pixar's BRDF, however I haven't optimized it well enough (not at all), so my frames are shit.

 

 

Well what both you an OP are probably looking for, at least for GPU stuff, is the Disney BRDF: https://disney-animation.s3.amazonaws.com/library/s2012_pbs_disney_brdf_notes_v2.pdf

 

Which most everyone seems to use a variation of now, plugin things like GGX/smith geometry term, other optimizations. In fact the above offers a lot of things most don't use, usually concentrating on the metalness/roughness. I've not seen a lot of the sheen/etc. stuff done. Besides you'd want to optimize that out to save registers/G-buffer space/etc. anyway.

 

This, specifically the UE4/Black Ops 2 stuff, offers a more GPU centric view of PBR: http://blog.selfshadow.com/publications/s2013-shading-course/


In Topic: SSR reprojection

12 August 2016 - 03:41 PM

What you want is called "Neighborhood clamped temporal anti-aliasing/reprojection" AKA http://advances.realtimerendering.com/s2016/s16_Ke.pptx


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