are some examples for VXGI cone tracing in materials.
is a reflective material:
is a refractive material - the custom function is “refract(-CameraVector, Normal, IOR)”:
And is how they look in a scene, reflective sphere on the left and refractive on the right:
Remember to check the “Vxgi Cone Tracing Enabled” box in the material properties, and that the material has to be translucent.
Also vxgi functions will not work in the material editor preview, only in the scene.