Joining curves actually Merges them instead. Ouch. New in R6?

So why is Join (curves) actually Merging them?

I often want Join and then be able to Explode. I also often want Merge, but now it seems I cannot decide which of the two will happen!

I recall R5 only joined curves (could be exploded again). But Merging curves was difficult although sometimes desired. As I see it Merging and Joining are two useful but different use cases, but now they seem to be conflated.

Or is there something I can do to prevent Curves from Merging on Join?

// Rolf

Hi Rolf - Joining should not merge but joining, moving a control point may make an unexplodable curve. That is not new, however.


Hm. So that must then have happened then.

But what is maybe even worse is that Join modifies the structure of the curves (becomes more complex):

Fig. Before and after Join:

Above I had planned to get four control points for every surface section when extruding this curve. But I can of course extrude before joining, and Join the surfaces afterwards. I really thought this had changed since R5, but if you say so I must believe you.

// Rolf

Hi Rolf - joining has to make the curve the highest degree of the input curves - this will make lower degree curves more complex looking… that is also ‘how it’s been since the dawn of time’, though, I’m told, there is a way to avoid this, technically…


Ah, I should have understood this!

Apparently I didn’t try very hard to make simple surfaces in 2016 when I first tried to do some surfacing, so now all the tricky bits floats up to the surface when I actually try to simplify… :grinning:

If you want to keep your extruded surfaces as clean as possible, you can also first extrude the individual curves, then merge the surfaces into a single surface (yes, a surface, not a polysurface) with the “Smooth=No” option. This way, you can simplify the geometry, especially when you have to deal with intersecting surfaces or polysurfaces for Bolean operations or fillet edges.

The following is a very good example showing where that technique solves a problem that occur with surfaces that were joined instead of merged.

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Yes, that is my strategy for now.

What I had already drawn some years ago was, among other things, a car grille which at the time looked OK in my eyes:

but a closer look at the surface structure reveals the ugly truth:

So I try to make better (simplified) curves as to recreate some parts with cleaner surfaces. Working on it.

An old Swedish beauty in the making:

// Rolf

Ah, I see - the fender query now has context.


Yes. :slight_smile: Same thing there. But I will fix it sooner or later. I’m adventurous you know…

// Rolf

Took another stab on it. Surfaces bent and curved in all directions but now very much better, much cleaner structure. Getting there.