3d Line drawing utilizing OpenGL shaders, the way to repair this damaged instance?

Why do not these shaders offered on this web site work?
https://vitaliburkov.wordpress.com/2016/09/17/simple-and-fast-high-quality-antialiased-lines-with-opengl/

I attempted adapting it to a extra ‘current’ model of OpenGL, with the next consequence.

vertex shader

#model 330
in vec4 Vertex;
uniform vec2 uViewPort; //Width and Top of the viewport
uniform mat4 ModelViewProjectionMatrix;
out vec2 vLineCenter;
void predominant(void)
{
  vec4 pp = ModelViewProjectionMatrix * Vertex;
  gl_Position = pp;
  vec2 vp = uViewPort;
  vLineCenter = 0.5*(pp.xy + vec2(1, 1))*vp;
};

fragment shader

#model 330
uniform float uLineWidth;
uniform vec4 uColor;
uniform float uBlendFactor; //1.5..2.5
in vec2 vLineCenter;
out vec4 LFragment;
void predominant(void)
{
      vec4 col = uColor;        
      float d = size(vLineCenter-gl_FragCoord.xy);
      float w = uLineWidth;
      if (d>w)
        col.w = 0;
      else
        col.w *= pow(float((w-d)/w), uBlendFactor);
      LFragment = col;
};

And I’m giving it a sound MVP matrix.

    glm::mat4 View = glm::lookAt(
            glm::vec3(0,0,2), 
            glm::vec3(0,0,0), 
            glm::vec3(0,1,0)  
            );
    glm::mat4 Mannequin = glm::mat4(1.0f);
    glm::mat4 mvp = Projection * View * Mannequin; 

And the opposite inputs/uniforms are set, too.
I even checked it with ‘renderdoc’.
(viewport is pixel values, proper? 1920x 1080 ?)

However all I get is a strong sq..

I simply need some depth/overlap conforming 3d strains for debugging…
Principally, I need this spoon fed.

The vertices all have a 1 for the w element, by the way in which.
Does that matter?
The vertex buffer is crammed appropriately, too.

Is that this simply outdated? I haven’t got the data/understanding to research this.
I am a brainlet ignoramus on the subject of this sort of factor. Please assist.

This appears so good and easy, but when this doesn’t work out then I am going to go for a kind of ‘single move’ approaches from the NVIDIA examples and whatnot.