Computer Graphics with Modern OpenGL and C++

Honestly, I'd say get your hands dirty with OpenGL when you know some very basic programming like pointers and OOP (not perfectly, even if you know the concepts).

Basically I followed along TheCherno's opengl series and I actually learnt a lot about just programming in general. For more knowledge about how an application is built, you can try starting the game engine series he has.
If you want something a bit more structuted as a course, you can go with this course. It's great and goes a bit more in depth than Cherno goes in his openGL series. But his game engine series are amazing, a goldmine of info on this topic and application architecture in general.
TLDR; Just learn the very basic things first, and just jump in. You'll feel a bit overwhelmed at first, but google all the doubts you have or ask here and you'll get the gist of OpenGL first hand (and how programming goes in general ig).
I too was going through all the c++ courses trying to prepare enough for learning more advanced stuff. If you do this, it'll never be enough and the tutorial cycle will never end.

If you want to learn OpenGL but struggle to read through articles such as learnopengl.com I recommend this udemy course. I think it's great for beginners as the instructor explains well. For the level of C++ needed, the Udemy instructor recommends up to pointers. Someone else in the comments mentioned that it's better to just follow along with a tutorial - I think that's good advice since you will learn lots more about C++ by doing projects rather than following C++ tutorials.

I wish you good luck on your learning journey :)

The class teaches OpenGL, which is a good foundation. I think it would be completely possible to take the skills from the class and go and learn whatever other graphics systems you wanted to explore (Metal/DirectX, etc). For web-based mobile graphics, WebGL is very related to OpenGL so you’d be able to go and use those skills on the web. Personally, I am using these two courses to continue learning and get to the point where I can do that:

https://www.udemy.com/course/graphics-with-modern-opengl/

https://webgl2fundamentals.org/

Maybe this course can help you, It was help me a lot. https://www.udemy.com/course/graphics-with-modern-opengl/

This guy has some of the best tutorials on C++ I have seen on youtube. If you're into computer graphics I'd also recommend this course - that's how I learned C++.

Honestly if you have a good Java background then basics of C++ shouldn't be all that difficult if I were you I would just learn a thing or two about iterators, templates and RAII and try to rewrite your Java projects in C++. Not the GUI ones tho. GUI is hell in C++.

If you are more of a visual leaner (videos) then I have a few suggestions. I haven't taken these courses all the way through yet because I want to get more familiar with modern/advanced c++ concepts first, but I have these in my library and the reviews are pretty solid:

https://www.udemy.com/course/graphics-with-modern-opengl/

https://www.udemy.com/course/learn-the-vulkan-api-with-cpp/

These are 2 Udemy courses (paid, unfortunately) that cover OpenGL and Vulkan with C++ and some other basics. Since it's on Udemy, their courses go on sale all the time and you can probably even get each of these for $15 a piece (I don't recommend paying full price if you don't have to).

Other than that, I'm not too sure about other resources or courses there are but these are 2 that I found and after watching a few of the introductory videos might be a good place to start if you can afford it.