VTK is primarily designed to render actual data (ie geometry or volumes described in a finite way) so doing sphere/ray tracing like stuff you can find on shadertoy is a bit hard. So really depends of what you want :
- If you want a scene rendered using sphere tracing for a fully procedural scene then a trick I can think of is to render a quad geometry taking the whole camera frustum and then assigning it a custom shader like @Paulo_Carvalho suggested
- If you just want to render some sea surface with actual wavelet geometry then you can create a plane geometry, subdividing it, warp it along a scalar field that you created and that is the result of your fractal noise and use the visualizations trick that @mwestphal mentioned
I don’t have any example to link but VTK is just not really designed for doing the kind of rendering you’re thinking of imo.