Blend surface doesn't blend the entire surface with history update


I understand that the rebuild (with increased complexity of the surface) is expected behavior (any way to retain the original complexity, btw?*) but I don’t understand why it no longer blends the entire surface edge.

That last part though, I really hope is a bug. Is it?

And even if it’s not considered a bug during the implicit history update, even doing an explicit “blend edit” doesn’t reset the blend surface back to cover the entire edge, and I saw no option for it either, which I really think should now count as a bug.

** fun fact, retaining the original complexity of surface rebuilds on history is something that Autodesk charges 5000 euro per year for, because only the two most expensive versions of Alias has it…

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Hello - it is not completely clear to me what you’re doing… At what point does Rebuild come in? You can force a ‘simple’ blend if the edges are not trimmed by turning off ‘Interior shapes’ in the BlendSrf dialog, though the continuity may suffer - depending…


I’m moving a CV on a curve that controls a lofted surface. On on side of that lofted surface I have a blend surface that “rebuilds” automatically (what I called implicit history update) the moment the CV gets moved.

The interior shapes checkbox is off and nothing is trimmed.

blendsrf.3dm (288.1 KB)

Hello - thanks, I see that on your file and here I can reproduce the ‘not the full edge’ part in my file but the blend stays simple, here:
BlendUpdate.3dm (46.9 KB)


I just checked with SR15. I get the increase in complexity 100% of the time, regardless of how I move the control point (but I hope it’s related to the “not full edge” issue, so it gets fixed at the same time).

It’s a shame that after all those years the History in Rhino is still not being fixed and completely destroys the ORIGINAL INTENT of the user. Rather than following the user-set values and settings in the dialog box of “Blend surface”, History does its own weird thing and most of the time produces overly-complex and/or ugly shapes. We need, a smarter History update on “Blend surface”. I had countless of issues with History update similar to what @eobet posted above. :upside_down_face:

Here is a simple example made with the latest Rhino 7 SR. Rhino’s History fails to update the blend surface, ignoring the blend factor set by the user.

Smarter history update on Blend surface.3dm (203.8 KB)

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