Thank you all for replies!
I can now show some more details.
I need to have trapzeze/triangle screens to simulate Holographic Pyramid view as presented on image below.
The screen should show 3 viewports: 2 trapezes and 1 triangle combined together.
Screen should show some 3D object from 3 sides.
So left trapeze - left side, triangle - front side, right trapeze - right side.
Blank on the upper center should stay blank.
I couldn't share more details before, but now I can 🙂
So to do this I tried to put viewport textures on 3 elements, and then place a camera which look on those elements - in result i got 3views of the object on the screen. But if it is possible to obtain with shaders - It would be better idea.
Could you tell me more about it?