How to implement a ShaderToy shader in three.js?

Question

looking for info on how to recreate the ShaderToy parameters iGlobalTime, iChannel etc within threejs. I know that iGlobalTime is the time elapsed since the Shader started,

Answer 1

This is based on various sources , including the answer of @INF1.

Basically you insert missing uniform variables from Shadertoy (iGlobalTime etc, see this list: https://www.shadertoy.com/howto) into the fragment shader, the you rename mainImage(out vec4 z, in vec2 w) to main(), and then you change z in the source code to 'gl_FragColor'. In most Shadertoys 'z' is 'fragColor'.

I did this for two cool shaders from this guy (https://www.shadertoy.com/user/guil) but unfortunately I didn't get the marble example to work (https://www.shadertoy.com/view/MtX3Ws).

A working jsFiddle is here: https://jsfiddle.net/dirkk0/zt9dhvqx/ Change the shader from frag1 to frag2 in line 56 to see both examples.

And don't 'Tidy' in jsFiddle - it breaks the shaders.

EDIT: https://medium.com/@dirkk/converting-shaders-from-shadertoy-to-threejs-fe17480ed5c6