Computer Graphics

OpenGL and GLSL: https://www.opengl.org
Learn OpenGL: https://learnopengl.com

Dead simple boilerplate for OpenGL: https://polytonic.github.io/Glitter/

Basic introduction to OpenGL: https://open.gl/
OpenGL function documentation: http://docs.gl/
Modern OpenGL Tutorials: https://ogldev.org/index.html

Real-Time Rendering Resources: https://www.realtimerendering.com/
Graphics Gems Repository: https://tog.acm.org/resources/GraphicsGems/
Graphics Group @ LTH: https://graphics.cs.lth.se/
Graphics Resource: https://www.scratchapixel.com/

Berkeley's Computer Graphics online lectures: https://cseweb.ucsd.edu//~viscomp/classes/cse167/wi19/onlinelectures.html
Nate Robin's OpenGL tutorials: https://user.xmission.com/~nate/tutors.html

Linear Algebra

Immersive Linear Algebra: http://immersivemath.com

C++

C++ tutorial: https://www.cplusplus.com/doc/tutorial/
Lecture slides from EDA031 (C++ programming): https://fileadmin.cs.lth.se/cs/Education/EDA031/lectures/cppoh4.pdf
Hacking C++: https://hackingcpp.com

Game Programming

Red Blob Games (Game algorithms) https://www.redblobgames.com
Handmade hero: https://handmadehero.org/

3D Model websites

PolyHaven: https://polyhaven.com
SketchFab : https://sketchfab.com
TurboSquid : https://www.turbosquid.com
BlendSwap : https://www.blendswap.com
CGTrader : https://www.cgtrader.com
Objaverse-XL :  https://objaverse.allenai.org
Materials, ambientCG : https://ambientcg.com