There are already rocks in the Object maker x3 If you want to change some textures then try this out! ^^:
Go into Feral Heart\Media\Objects\Rocks
Open "rock.material" in notepad
Copy and paste the Rock Texture you want into Feral Heart\Media\Objects\Rocks. (Size must be 4096x4096)
Rename it to e.g. rockTex7 (The next number that you need).
Copy and paste this into the note pad you opened up (Example):
material rockMat7
{
technique
{
pass
{
cull_hardware none
cull_software none
texture_unit
{
texture rockTex7.jpg
}
}
}
}
Open up 'ObjectMaker' and load the object you wish to re texture.
Select the Object and go into the Mesh section.
Where it says 'Material' type in rockMat7
Once you have done save it.
I don't think I can help you with converting meshes, however, you can contact someone who is experienced with this kind of thing x3
Good luck!