Trying to Understand a Shader

I am trying to understand a shader file.
They file has its own function to generate/produce noise.
They have a function call ‘col.r+=noise(uv.xyy*(12. … continues’.
I understand that ‘uv’ refers a texture with u being right/left and v being up/ down.
it seems that the xyy piece is getting a/ the color, but i can’t fathom what xyy would return.
Is it performing some type of color modification/substitution?


Apparently this is ‘swizzling’ in shader speak.
Now I have to go back thru and try to understand why.

again thanks

Have you tried the book of shades or the processing reference. Both are good intros. I understand a bit about basic shades, though difficulty ramps up quick with shaders.