wilfrid

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About wilfrid

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  1. I don't have an answer, but for those like me who prefer seeing pictures to their description, here are the slides I think lipsryme is talking about:       From the presentation: High Quality Temporal Supersampling
  2. Blinn Phong Normalization

    By the way, here is a "famous" article on the subject: The Blinn-Phong Normalization Zoo.
  3. I am not certain, but I think the formula in the link you refer to is a reformulation of the Phong NDF to account for light conservation (the formula used for normalized Phong specular BRDF). Here is some material that might help you answer your question.     In the 1977 paper Models of Light Reflection for Computer Synthetized Pictures, James F. Blinn talks about several possible Facet Distribution Functions that can be chosen to build a Torrance-Sparow model of a specular BRDF:   In the Global Illumination Compendium, Philip Dutré recalls the mathematical background of integration over the hemisphere:   A derivation of the normalization factor for the Phong NDF has been given on Fabian Giesen site:      
  4. Maybe it's a bit over-complicated compared to your needs, but here is a reference you might find interesting: "Real-time Realistic Ocean Lighting using Seamless Transitions from Geometry to BRDF" Project page: https://hal.inria.fr/inria-00443630 Paper: https://hal.inria.fr/inria-00443630/file/article-1.pdf  
  5. After you mastered all these BRDFs, you can try to combine them following the techniques described in this paper "GenBRDF: Discovering New Analytic BRDFs with Genetic Programming"
  6. Yes there was an other tentative about one year ago that was closed by Stack Exchange administrators because the traffic statistics were considered too low. However the requirement have changed since, as stated in this conversation: http://meta.computergraphics.stackexchange.com/questions/48/how-do-we-improve-the-question-rate We will make it work this time !
  7. Hi Graphics Programming enthusiasts ! This is a reminder that the Stack Exchange site proposition for Computer Graphics entered its Private Beta stage recently: http://computergraphics.stackexchange.com I think one of the objectives of the Private Beta is to evaluate if there is enough interest in the subject, to later promote it to a "full-size" Stack Exchange site. If like me you also appreciate the style of questions/answers posts of the Stack Exchange sites, I encourage you to visit the link above. I also encourage you to try to ask or answer to many questions ! The site should be an excellent complement to this forum. I am not sure if it is easy to sign up for the site during the Private Beta phase, however developers such as Nathan Reed seem to be offering invitations: https://twitter.com/Reedbeta/status/629174385836855296 By the way I will send you invites too if you ask me !
  8. I recommend you read these excellent presentations by Emil Persson that are essentially low-level considerations about shader code: - "Low-Level Thinking in High-Level Shading Languages" (GDC 2013): http://www.humus.name/index.php?page=Articles&ID=6 - "Low-level Shader Optimization for Next-Gen and DX11" (GDC 2014): http://www.humus.name/index.php?page=Articles&ID=9
  9. x

    While you cannot access documentation about the PS4's graphics API without signing an NDA, you still can read extremely interesting things about the family of GPUs that are [said to be] used in the PS4.   This article says "PlayStation 4 Rumored to Use AMD Fusion CPU/GPU". This thread claims "The PS4 uses a modified HD 7870". This Wikipedia page lists the HD 7870 in AMD's "Southern Islands" series.   Well, here is an interesting document about AMD Southern Islands Series Instruction Set Architecture. The first two chapters are a good introduction to that hardware. You can also find a description of the PM4 packets those GPUs use in Radeon Southern Islands Acceleration, and registers are described in Radeon Southern Islands 3D/Compute Register Reference Guide. About Fusion systems, this presentation about Memory System On Fusion APUs might be instructive.     Now, most of these suggestions are based on rumors, but they sometimes are close to reality... In any case, those documents are interesting to skim through if you're into graphics programming.
  10. I am looking for clear and easy-to-understand references about (modern) GPU architectures, that would for example explain (in generic terms) the flow of data, the way problems such as synchronization issues are handled. etc.   Most often the documents I find are: - Presentation slides - Technical specifications   Since those are quite hard to understand, I am looking for explanation with sentences written in "regular" English. So far the closest thing to what I need are probably the posts "A trip through the Graphics Pipeline" by Fabian Giesen.   Are there any good books with the same level of quality and clarity, dealing with GPU architecture?    
  11. GLSL Driver optimizer

    My game engine is designed to be easily ported to any platform, as a result it didn't make much sense to have platform dependent shaders, I couldn't find any libraries for the latest shader model, so I came up with a workaround to write them in C# (basically using the DLR to build a shader as a result of the execution of the C# code). By the way, if you like C#, you will be interested by the Paradox3D engine. As for their shader system, I think it is mainly an extension of hlsl, that they convert to glsl for you. https://github.com/SiliconStudio/paradox
  12. Example of Specular Aliasing

      Thank you very much for the links. I copy/paste the image here in case other readers want to see the difference:         Link to the .pdf one more time: http://blog.selfshadow.com/publications/s2013-shading-course/rad/s2013_pbs_rad_notes.pdf#page=20
  13. Several articles talk about the difficulty to avoid Specular Aliasing when rendering games: http://blog.selfshadow.com/2011/07/22/specular-showdown/ http://www.cse.yorku.ca/~amana/research/hilite.pdf ... However, I have trouble understanding in the first place what is the visual appearance of specular aliasing.   Does anyone has a concrete example, for example a screenshot of a scene presenting specular aliasing, side-to-side to a screenshot of the same scene where the specular aliasing has somehow been reduced ?      
  14.   Ok, thanks for the confirmation.
  15. For the sake of the original question I tried to plot the formula with Wolfram Alpha, but the results are not what I expected.   Simplified formula: http://www.wolframalpha.com/input/?i=polar+plot+c+%3D+cos%280.2+%2B+0.5*theta%29%2C+m%3Dmax%28c%2C0%29%2C+r%3Dpow%28m%2C5%29   Formula with "named parameters" (could not be parsed): http://www.wolframalpha.com/input/?i=polar+plot+l+%3D+0.5%2C+v+%3D+theta%2C+h+%3D+%28l%2Bv%29%2F2%2C+c+%3D+cos%28h%29%2C+m%3Dmax%28c%2C0%29%2C+r%3Dpow%28m%2C5%29