defining reference plane with 3D points

[butterbrot]

Hi - is there a way to define a reference plane with 3 points in space?

The background: I have to model an underground garage where no floor slab is horizontal one of those where ramp and parking slots are the same. So in the end it is something like a rectangular spiral...

The problem is that:
1) the floor slab is twisted
2) as every niveau has a different hight (and so the ramp decline) I can't copy anything.

Can any of the experienced user give me a hint how to start? I saw one tutorial which propse to create difficult floor with the toposurface tool, export in dwg and reimport the result - is that a good idea?

And - I saw in another tutorial that there are z-Coordinates visable to beam ends? My version does not show z-Coordinates. Any hint to turn it on? (As this might be very usefull for checking...)

Thanks,
Max

[PeterJ]

If it is truly some form of spiral that you are after then a spiral stair could be used and oversized. You would simply define a railing to the stair that defined your ramp and then remove the remaining geometry. Search on spiral stairs for the methodology behind this in more detail - you are looking for a monolithic stair with a solid handrail.

Alternatively long long long ago mtogni, I think, uploaded a piece of rather complex geometry that defined a ramp from standard geometric forms that came together to make a spiral ramp. He actually defined some kind of inclined plane and then cut it to form a circular route, it was a very neat piece of geometry indeed and is worth searching on for how to achieve your needs my modelling the basic structure instead of using a stair or similar as a work-around