To the best of my ability, all I can tell you is that there’s a lot that’s wrong with your shader code.
I can see a lot of copy-pasted code from the internet and errors as well. You seem on the right track as you’re beginning to become comfortable with glsl and c’s syntax but asking for help on a task like this won’t accomplish your main goal in a meaningful way.
This is likely not the best place to ask, not only because this is a forum for specifically Processing as an isolated language but also because there are likely not a lot of people in this forum using P3D specifically to write shaders.
If you have specific questions on shaders you can reach out to a community that is better focused and centered around writing shaders. If you want to get a real leg up in learning shader basics as well as to start learning more practical applications I recommend finding some tutorials that are suited for beginners who are comfortable with the syntax but not the proper application or a professional course on computer graphics. You can even watch some live coding demos using shadertoy
Processing is very beginner-oriented and therefore unfortunately doesn’t have a lot of community members who know the first few things about shaders. I know enough about them to get them started and to create unique effects, but I’m just starting to learn the terminology and best practices and wouldn’t feel like any criticism I could give you about your code would be truly constructive. I don’t think anyone in this forum could do so either without spending a full afternoon and a half with you.
I hope you take some of the links I posted and use them. They helped me a lot in the long run.