How to animate concreting sequence?


It’s about animating a concreting sequence by section cut. The concrete inside the formwork box only display as a hollow mass in between the top and bottom section plane. How to display it as a solid mass?


It’s not clear whether this question is about animation, as your title would suggest, or about covering the empty space exposed by a section cut, as the question itself suggests.

There are no solid masses in SU. When the interior of an object is exposed, it becomes obvious that objects in SU are hollow, consisting only of a thin skin surrounding empty space. If you want a solid surface exposed when you look inside an object, you must construct the surface and place it artfully to cover the opening. It’s sleight of hand–a parlor trick. Your animation would have to switch on the section cut and the face covering the opening at the same time to create the illusion of solidity where there is none.

You can create the face covering a section cut in two (or more) ways. First, you can generate a group from the the edges surrounding the section cut by right-clicking the section plane and selecting “Create group from slice.” You can then place a face on those edges and apply a texture. Alternatively, you can use the plugin “Section Cut Face” by TIG.



Thanks for the advice. I guess the small file that I have attached might make my confusion clear.

concreting.skp (103.9 KB)


Rather than use a cube if you just use multiple faces, no sides, you get this effect.


i’m sorry, I did’t get it.


All I did was remove all but the bottom face of your concrete block, then copy that face 20 times up to the top. So now when the section plane moves it is seeing the faces rather than the z-fighting of the sides of the block.


Thanks, that was tricky.


I don’t think you’re particularly confused, but here’s a slightly different appoach:

concrete.skp (180.9 KB)

Aha, it would seem Box beat me to it with about the same alternative approach.



Is this not easier?
Cut the top face of concrete
Pull the inside faces in 3mm (so you don’t get the weird double face texture thing happening)
hold [shift] and erase the visible edges (smooths them)
Paste the top face of concrete
turn off "view hidden geometry"
concreting1.skp (203.4 KB)


There are always many ways to skin a cat.


There’s quite a difference between using a well know old phrase and posting an image that many people would find offensive.


Agreed. The pun was ok,… the photo is not !