You probably chose to install Resistance Vegetation, but didn't select the correct display mode.
Check your OFP Preferences, there will be a box labelled "Display device". This really ought to be
Direct3D HW T&L on a modern computer. If it's just "Direct 3D", try changing it to enable
Hard
ware
Texture &
Lighting.
If that's not the case, you'll have to follow thunderbird84's advice and re-run the installer:
When you run the launcher, you will have the choice between [Direct 3D and Direct 3D HWTL], better choose the second option. (If you would encounter weird white textures in game then delete @ffur85/dta/Data folder and take out Data3d.pbo and Data.pbo files and choose the other option).