vec2 | 2D vector class for AS3 | Machine Learning library

I am new to Glsl and have absolutely no idea what I am doing. I have been looking for resources to learn however, most of them are either incredibly general like the book of shaders or really overwhelming like this reference.

Anyways, I am looking for what exactly a "fragment" is. I think it is just referring to pixels that need to be rendered. If this is the case what does gl_FragCoord return? I've messed around with it and I don't think it returns the x,y of the current fragment but the book of shaders says

"vec4 gl_FragCoord, which holds the screen coordinates of the pixel or screen fragment that the active thread is working on."

I have also seen that it returns values from 0 to 1, initially (0.5,0.5). I have no idea what (0.5,0.5) is referring to though. Is it percentage of the screen? Like on a 800px by 800px screen will 0.5,0.5 correspond to 400,400? If so than why doesn't this sort of thing work:

I am trying to run a code that has a GUI built with pyglet. but it gives this error. I have searched and found that I need to directly set the version of GLSL to be used by the code but I don't know how. would be happy if you helped me out with it.

I would like to deduce a class' (with default template parameter) typedef with c++17 automatically. Does somebody know if this is possible? The following code tries to illustrate this:

I'm trying to change the perspective of my square in OpenGL but when I put some vectors to multiply with my position's vector the image disappears and don't know if I changed the perspective enough to make it disappear from the screen or it is a rendering problem which I think that is more probable

Vertex Shader:

I'm trying to add a new function to an existing class Node defined inside the namespace cc. The namespace is declared as follows:

creator.d.ts

I want to create a struct called Vec2 which looks something like this:

I'm trying to use Armadillo C++ library in my swift code to create sinusoidal curved arrow. Earlier it worked well with Objective C. But when I'm trying to do the same implementation in Swift, it's showing 'armadillo' file not found error.

I've downloaded the file from https://github.com/gadomski/armadillo/tree/master/branch-5.600/include path and copied both armadillo_bits folder and armadillo file into the project.

I've created a Objective C++ Wrapper around the C++ class too.

Objective C++ Wrapper DrawSinusoidal.h file

My diffuse lighting doesn't seem to be working properly.

Fragment Shader:

I'm trying to unravel a bit of the dark unknown that is webgl via PixiJS library. At this point, it probably should be noted that I haven't used PixiJS for awhile either, but it seemed to be a much more preferable approach than to manipulate the lower level underlying webgl state.

My logic is currently this: I create two buffers ("current" and "previous") with the same fragment shader as well as a render buffer and a "render" fragment shader. Both buffers start off with the same content: a fill that is rgb(255, 10, 0) for every pixel.

Right now, the fragment shader does this: