Raycast as example "HandInteractionTrainScene

Hello everyone,
I'm new to developing it under unity, and I have a question about Raycast. I use the oculus integration of course.

I would like to reproduce the parabolic raycast of the "HandInteractionTrainScene" example. The raycast that appears when approaching the windmils.

Anyone got an idea? or better, a tutorial?
I try to understand via the example but I come to nothing.

Thanks in advance