Hi Guillame, first, this is a multipass shader, as you can see there is a buffer and then the main image in the "image" tab in Shadertoy. Did you see my tutorial about multipass shaders? https://youtu.be/9O80hGMtW6Q Second, the bitwise operators like ^, >>, << etc. are not supported in glsl 1.2, which is the version Max uses. In the future this could change but not at the moment, unless you try to give it the version 1.3 next to the language spoecification, but I'm not sure this would work. Third, #define is not supported in glsl inside Max, you simply have to state those variables as normal ones, using a definition like vec2 R = iResolution;

So, that's it, you can try to use different methods to replace the bitwise operators, this link should give you some hints: https://scratch.mit.edu/discuss/topic/97026/

Good luck!