Self Shadow hosts course notes and links for the SIGGRAPH Physically Based Shading in Theory and Practice courses, run by graphics engineers.
HN commenters use it as a rendering reference, citing the Disney BSDF notes and the 2013 course as among the best references.
I picked up graphics maybe three years ago and have been mostly learnt all the stuff I needed through different sites scattered all over the internet.
For ray tracing Peter Shirleys books are very good.
OpenGL stuff are usually found at docs.gl, https://learnopengl.com/About.
For Physically Based Rendering (PBR) material checkout the bool Real-time Rendering and all the cool stuff has been coming out of Siggraph these past years, https://blog.selfshadow.com/publications/s2013-shading-course/.
If you can, go take an elementary linear algebra course or prepare to spend time studying these. It is well worth it.
One thing I have found when hacking on my own engine (see here: https://github.com/Entalpi/MeineKraft) is that graphics APIs (especially OpenGL) can have a lot of hidden meanings or even old names still being used, etc. Try to find out how the API evolved and get the reasoning behind the design decisions. This way it makes more sense and it gets a bit easier to learn.
GLHF
The blue light of the sky is technically the result of Rayleigh scattering of the sun through the atmosphere, which can be emulated (and often is these days! [0]), but fair; it's often cheaper and easier for an artist to model them separately. I was going for a classic physics demonstration to point out how simple sources can often result in beauty.
[0] The classic is Naty Hoffman's 2002 work on atmospheric scattering http://developer.amd.com/wordpress/media/2012/10/GDC_02_HoffmanPreetham.pdf , but it has been developed over the years, e.g. Sebastian Hillaire's work on both Frostbite https://media.contentapi.ea.com/content/dam/eacom/frostbite/files/s2016_pbs_frostbite_sky_clouds.pdf and Unreal Engine https://blog.selfshadow.com/publications/s2020-shading-course/hillaire/s2020_pbs_hillaire_slides.pdf
This is one of my favorite graphics/rendering papers from 2017; great work from the entire DWA Moonray team! In addition to the main paper, there are some other materials that were presented at HPG and SIGGRAPH 2017 by the same team.
HPG Slides: http://www.highperformancegraphics.org/wp-content/uploads/2017/Papers-Session5/HPG2017_VectorizedProductionPathTracing.pdf
SIGGRAPH Course Notes (the relevant part begins on Page 35): https://jo.dreggn.org/path-tracing-in-production/part1.pdf
SIGGRAPH Slides: https://jo.dreggn.org/path-tracing-in-production/MoonrayV3.pdf
Also, the actual shading system they used was also presented at SIGGRAPH 2017: http://blog.selfshadow.com/publications/s2017-shading-course/dreamworks/s2017_pbs_dreamworks_notes.pdf
Kotaku is a video game blog, so "Next-Gen" specifically refers to games running on Playstation 4, Xbox One and sometimes high-end PCs. Specifying "Game" on Kotaku is kind of redundant as almost all technology related posts are referring to games in some way. I could see it on a general technology, art or VFX site though.
The siggraph physically based shading course is a great resource if you're interested in the techniques people are using in production.
2012 - http://blog.selfshadow.com/publications/s2012-shading-course/
2013 - http://blog.selfshadow.com/publications/s2013-shading-course/
2014 (not yet available) - http://blog.selfshadow.com/publications/s2014-shading-course/
- As a starter Realtime Rendering [0]
- The siggraph courses on shading [1]. The 2017 course will be on 30th of July [2]. Current techniques from AAA engines.
- Papers from JCGT [3].
- Plus the paper collection from Ke-Sen Huang linking all graphics related conferences [4]
have fun reading
[0] http://www.realtimerendering.com/book.html
[1] http://blog.selfshadow.com/publications/s2016-shading-course
[2] http://blog.selfshadow.com/publications/s2017-shading-course-draft/
[3] http://jcgt.org/read.html?reload=1
[4] http://kesen.realtimerendering.com/
The Disney BSDF [1, 2] is extremely flexible and offers a lot of artistic freedom. The only real limitation is that the BSDF is required to be energy conserving, but that's hardly a limitation. A physically-based renderer is still able to produce non-photorealistic results.
[1] http://blog.selfshadow.com/publications/s2012-shading-course/burley/s2012_pbs_disney_brdf_notes_v3.pdf
[2] http://blog.selfshadow.com/publications/s2015-shading-course/burley/s2015_pbs_disney_bsdf_notes.pdf