Hi Metadem, CAD programs like MoI are focused on making accurate man made type mechanical parts. Rocks do not fit in that category of shapes, so MoI is not the right tool to use for that kind of object.
Something like ZBrush or 3D Coat would be a good fit for it. Or you might try Sculptris.
We have been using MOI3D to create primitives for an almost free ($6 donation) surface modeling program called MeshMolder. https://www.meshmolder.com/
In these images we see a Sphere deformed by pushing and pulling points in MOI3D then exported as .OBJ. It was then imported to Meshmolder for surfacing with a rough texture. The whole process took just a few minutes. The pushing and pulling can cause surface breaks which can be fixed in Meshmolder.
MOI3D and MeshMolder make for a very good combination of tools. Ultimately, the developer of Meshmolder hopes to have a similarly priced rendering engine.
Download 3D rocks models and convert these quad mesh topology objects with Blender (a free program) and then import them into Moi3D as subdivision surfaces.
tutorial triangulated mesh to quad
1.) Draw irregular polygon shapes on each of the 3 axes (I used three 5-sided shapes).
2.) Select all three closed shapes and run the boolean merge command.
3.) Delete all the extraneous parts and you're left with a rock shape.
It's hard to control with any artistic eye, but the results are very easy to produce.
I found that you can "find your groove" when doing this process and make oblong rocks or whatever.
I'd imagine you could make the rock more "shale-like" if you change the lines to slight concave curves.
A "tumbled rock" look could be achieved with convex curves.
Nothing beats the SubD process for boulders and round river rock though.
Note: I should mention that Pilou made me aware of this way of modelling. He's a genius!
:) Cool...you must now make some landscapes render with them! ;)
Not made here but look this other trick ;) Input an image of your Moi's Objects (your rocks) inside Wombo with some % influence ...et voilĂ ! :) https://www.wombo.art/
Or in direct you can also with The magic free Wombo ;)
tiny cubic geometrical rocks filling landscape
Here with a poly modeler but that will be exactly the same in Moi3D! :)
Just use the ExplodeMove Function after any Trim (Press Tab write ExplodeMove) hidden function...