Will this be fixed in Rhino 7, or will be left forever bad?
The fact that the program is incapable of doing proper offset of quite simple polylines makes it impossible to work on some projects, or at least forces me to work extra time in trying to figure out different ways to overcome the bug.
Loose offset preserves the structure if the curves (and surfaces, if the input is a surface) and is very important while offsetting curves with a degree higher than 1.
The existence of this bug also makes no sense, as well as that it causes inaccurate offset on curves that include curves with a higher degree. Here is an example with the bottom left end being a sharp edge, G1 arc and G2 blend.
That trick will not help, because the bug is present even one higher degree curves. Not to mention that the offset tool fails to properly offset the G1 arc and G2 blend curves in the example above.
Rhino is known to create very inaccurate results while working with Degree 5 curves and surfaces. In this example it even fails with the simple G1 arc, which any other CAD software I know can handle properly. The problem with the G1 arc is that Rhino resets the weight of the middle control point to 1, whereas the weight of this point on the input arc is 0.707106781186831.
Loose offset preserves the structure if the curves (and surfaces, if the input is a surface) and is very important while offsetting curves with a degree higher than 1.
You are aware that offsetting a curved curve or surface without the “Loose” option results into an output curve or surface with noticeably greater number of control points, which is unwanted. This is especially critical for when a lofted surface must be created between two curves or surfaces, or if Class-A quality is needed.