Fix ExtrudeCrvTapered

I want to make a request for the output of extrudecrvtapered to be improved. A better result can almost instantly be achieved, after running the command, duplicating the edge of the result, and performing a sweep2 with the original curve to be tapered as a second rail. Using just a straight cross section, refitting rails so as to not get polysurfaces where surfaces may be sufficient at breakpoints and so on.

Is there a you track or anything that I can add a vote to? Just to try and do away with the triangular surfaces that you get as standard with this tool at break points.

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Yep, it is messy - FitSrf on the result is also often a possibility if the result is a single surface. I do not see a bug track item about this, though I’ve moaned and groaned more than once. I’ll make one.

Another useful workaround is, because the density increases with distance for a given angle, is to extrude a very very short distance (this has the extra advantage that the result will be less apt to split up into a polysurface) and then ExtendSrf to get the full depth.

Another good workaround, for now:

DupEdge the top of the extrusion, Rebuild the result using the Master Curve option > Select the extrusion input as the master, then Loft the original input and the rebuilt edge.

-Pascal

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Thanks Pascal! Yeah it’s always seemed odd that it produces those bad 3 sided surfaces when Rhino is so capable of better.

Could something be prototyped soon?

Hem, well, as long as you go with ‘prototype’… Here’s a first cut - currently it filters out closed curves - it can handle closed smooth curves but not polycurves with kinks so for the moment, only open curves, to see if it does anything useful. The result is a ‘loose’ tapered object i.e. with the same structure as the input curve. Baby steps, I will add this to the bug tracker for a proper developer to work on for real.

ExtrudeCrvTaperedLoose.py (9.4 KB)

To use the Python script use RunPythonScript, or a macro:

_-RunPythonScript "Full path to py file inside double-quotes"

Guaranteed somewhat tested.

-Pascal

Below is an example of something that is just unusable.

I have to ask too… could you show me the Corners=Smooth option in practice? I’ve never seen it do what I suspect it’s intending to do… but, I can’t say I know it’s expected to do for sure.

Sharp
The corners of the tapered surfaces will extend to meet at sharp corners with position (G0) continuity.
Round
The corners of the tapered surfaces will be filled with filleted segments with tangent (G1) continuity.
Smooth
The corners of the tapered surfaces will be filled with blend segments with curvature (G2) continuity.

image

ect_badcornerhandling.3dm (35.3 KB)