Urgent help needed about clip mapping and displacement

Hellow, I’ve read in the vray doc it was possible to execute clip mapping with 2D displacement, that would save me some hours of work if I could manage to do it,

fo example a checker the displacement slot of the vray modifier
I don’t know what to check so the black parts disappear ?

thank you for the help in advance,
best regards,
chris-x

Just check “water level” and make it’s value more than zero but less than the overall amount.

working perfectly, thank you very much