webGL,SLGL? where should I start with this code - webgl

Question

I am familiar with C or C++
However, I am a quite newbie for WEBGL and GLSL.
It might be too basic or silly question though... I appreciate you give me some hints.
I found this source code which makes the great CG graphics.
I want to compile this by myself, However honestly saying I am not sure what it is , and what with compiler I can compile and make this work .
#define R rotate2D
for(float i,e,g,s;i++<1e2;g+=e*.2)
{
vec3 n,p=vec3((FC.xy-.5*r)/r.y*g,g-4.);
p.zy*=R(.4);
p.z+=t;
e=p.y;
for(s=1.;s<6e3;s+=s)p.xz*=R(s),n.xz*=R(s),n+=cos(p*s),e+=dot(sin(p.xz*s),r/r/s/3.);
n.y=1.;
n=normalize(n);
e-=snoise2D(p.xz*40.)*n.y*n.y*.4;
o-=exp(-e*9.-5.);
}
o++;
So at first, I started to learn about webGL.
And finished learning basic webGL
However I cant make it work with webGL.
Next, I started to learn about SLGL on unity,,, however it's not hit the spot.
What should I learn to compile this???

Answer 1

This looks a piece of a GLSL shader, and you would compile that with gl.compileShader()
But it's incomplete. First of all to be completely compilable it needs a main function that sets gl_FragColor. And I see a reference to snoise2D and rotate2D which should be functions, but are missing. And a least a few local undefined variables like FC and r. So without those pieces, this won't compile.
If you can solve those issues, you should be able to plug into something like ShaderToy without have to invent a whole WebGL application from scratch. But if this shader is meant to interact with specific geometry that might not work at all.
It's hard to advise more without more info on what this is, how its intended and what all that single letter variable names are supposed to mean.