This question goes out to anyone familiar with doing OpenGL/GLSL. HOW MUCH math is necessary to really make full usage of the OpenGL Shading Language? I already know I should be good at linear algebra, trigonometry, and some geometry. But trying to figure out a path to re-learning (I'm assuming this is all the stuff I learned in high school and college, thus re-learning) all this without getting bogged down by grinding and getting overwhelmed. I downloaded a bunch of textbooks offline I could find, but don't know the most effective way to learn all this.

Any advice? I could use some.

Best way to learn it is to have a real problem that you need math to solve. If your need is purely 2D tinting sprites or basic stuff like that, you don't need any advanced math skills in particular, and definitely nothing you need to learn separately from just working on the shader.

I'm not as familiar with the 3D space, but I imagine that's where most of the linear algebra and stuff comes in. But still, you're probably working on something that many people have done before, so you can learn from existing examples and then go back to the books to clarify things you don't understand.

my math knowledge was over-the-top excellent during high-school, during comp-sci bachelor my math skills got critically rusty.

I had some experience doing some heavy geometry computation. generally I just solve one problem at a time, trying to find a solution for each directly by searching a lot online and learning as required, copying algorithms from forums, Stack Overflow or from source-code of existing libraries/software.

I think studying math itself gives you an edge to be able to understand and adapt solutions better, and I'm excited to improve my math knowledge. but spending months devouring several books before you write a e.g. a camera or generate a mesh is enormously unproductive for the sake of actually realizing a software project. when I'm stuck, I just ask for help to smarter people, I'm at an university context, so it is easy to find math experts to provide me working solutions in mere few minutes. these math experts, they already did all the studying, it only makes sense to take advantage of that.