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Help with GPU Pro 5 Hi-Z Screen Space Reflections

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#1 Bruzer100   Members   -  Reputation: 117


Posted 12 July 2014 - 07:54 AM

Hi there!  I'm trying to implement chapter 4 of the Lighting and Shading section in GPU Pro 5.  Basically, how to optimize my screen space reflections using a mip-mapped Z buffer to quickly converge on the intersection point of my reflection ray.


Sadly, the author wasn't allowed to release the code/demo he talks about in the article, so I've had to work out most of the shader myself.  I'm close, but one thing I don't get - if you are always starting at a lower mip in the HiZ buffer, won't your starting ray depth often (always?) be _behind_ (greater Z) than what you read from HiZ buffer?  because you make the HiZ buffer taking the min(...) of the more detailed mip.


If you've implemented that chapter, or even just read and understood it, or using HiZ tracing before, I'd be curious to hear your thoughts.




#2 WFP   Members   -  Reputation: 494


Posted 12 July 2014 - 01:19 PM

Hi Bruzer100,

I was also preparing to start implementing something similar, and was disappointed to find that the code was unavailable, especially since several places in the chapter specifically tell the reader to consult the source.  I'm sure when I do start my implementation in the next few days, I'll probably run into similar issues like the ones you've come across, so if you wouldn't mind sharing what hurdles you've had to work around that weren't called out, or even want to share your implementation, it would be highly appreciated.  I'll bookmark this thread so that when I do start my implementation I can add anything I find to be valuable, especially if it was left out of the book's chapter.