Displacement in one direction

[max.m]

Hi, generally i use a vray displacement modifier on an extruded spline to create grass. Now i face the problem that i need grass on a flat roof for bicycles and see the displacement of the Grass object from below. Can someone tell me how to make the displacement only in one direction?

[sanmb]

Convert it to edit poly and detach the polygon and apply displaced material to polygon.

[max.m]

i use the vray displacement modifier, not a material with displacement! when i detach a polygon and add the vray displ. mod. the result stays the same. i get the dispersion on both sides of the polygon, what i want to avoid!

[sanmb]

Hi Max,

It works for v-ray displacement,you can hide unwanted surface by creating other object or copying the same and scaling..........