I have a number places where I need to create bossings for pipes that create a smooth transition from rectangular shapes to circles. The image kind of, sort of shows what I am trying to do. But I need to have a smoother transition. I have tried several different approaches but nothing has satisfied me.Usually the problem is bulging at the corners.
What it looked like I need is to create transitional frames consisting of eight arcs: one at each side and one at each corner.
The radii at the corners go from zero to that of the target radius. The radii at the edges go from infinity to that of the target radius. The problem is how to keep the arcs of the intermediate frames tangent.
Is there any good method that would allow me to adjust the position of one arc such a frame while maintaining the tangency of all the arcs in the frame.