Rotate one polygon of a cube and keep sides parallel

[Anonymous]

Hi,

When I rotate the top polygon of a cube, the sides do not keep parallel. I understand that it is because the top polygon keep is size and when you rotate it becomes less larger because of the angle.  

I need to rotate the polygon and keep the sides parallel (green lines in the image attached). That means, the top polygon would change shape which is ok.

Does anyone have an idea how I could do that?

Thanks

d

[Anonymous]

Well, you can just move the top vertices instead of rotating the top polygon?

[Anonymous]

Yes, I could do that. But I forgot to mention that the cube was a quick and easy sample of what I want to do.

The actual shape I need to rotate the top part is composed of several polygons. The top, sides aren't made of one polygon. 

Thanks for taking time to answer my question. 

[Anonymous]

Without knowing what the shape should look like, it`s difficult to suggest something.

There might be various ways to do what you want to achieve. Snaps,FFD or different modeling techniques.

Here is an example with FFD2x2x2 modifier:

Can you perhaps post an image?