Double curtains and tulle on a curtain tape. Designed for a trapezoidal dormer window.
The scene includes a simplified model of a beveled trapezoidal window in the wall.
Model colors can be easily changed in the material settings.

https://3dsky.org/collection/shared/5255126  collection of my curtains.

For Corona render, it is recommended to install version no lower than 1.5, since the glossiness of materials is configured taking into account PBR.

If you are working in V-Ray version lower than 3.1, then be careful, in the materials in the BRDF section there is Microfaset GTR (GGX), if your version is older, then the BRDF field will be empty. Select Blinn, Phong or Ward - what is preferable for you.